SMITHSONIAN CONTRIBUTIONS TO BOTANY

NUMBER 5

Burrett Nelson RW~ The Woods and Flora of the Florida Keys: ccPinnatae”

SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON 1972 ABSTRACT

Barrett Nelson Rock. The Woods and Flora of the Florida Keys: “Pinnatae.” Smith- sonian Contributions to Botany, number 5, 35 pages, 35 figures, 1972.-The “Pin- natae,” comprising six families of woody plants with pinnately compound leaves, is represented on the Florida Keys by at least 16 species. The taxonomic treatment of these families at the ordinal level has been inconsistent. The purpose of this study is to correlate the data derived from intensive study of the xylem anatomy of these 16 species with data from the literature concerning these and other members of the families involved, so that new insight might be gained concerning the taxonomic relationships among these families. This study indicates that the members of the Pinnatae are anatomically homoge- neous. All members possess simple perforation plates, vessel elements having alternate intervascular pitting, fibrous elements with small slitlike simple to vestigially bordered pits, and apotracheal and paratracheal axial parenchyma, or both. Secretory struc- tures, such as crystalliferous idioblasts, parenchymatous cells containing “gum,” and intercellular canals, are of wide occurrence within the Pinnatae. In addition, many species possess septate fibers and axial parenchyma arranged in aggregate patterns, with banded arrangements being most frequent. There is no anatomical basis for the separation of families into distinct orders in my view. The only separation of families within the Pinnatae suggested by a syn- drome of several unique characters, in addition to those common to all members, is the formation of an Anacardiaceae-Burseraceae complex. The members of the Pinnatae belong to a taxon corresponding well with Cronquist’s Sapindales. Phylogenetically, the Pinnatae constitutes an advanced taxon, based on xylem anatomy.

(Scientific Article No. A1731, Contribution No. 4506, of the Maryland Agricultural Experiment Station, Department of Botany.)

Oficial publication date is handstamped in a limited number of initial copies and is recorded in the Institution’s annual report, Smithsonian Year.

UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1972

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 50 cents (paper cover) Stock Number 4700-0152 Barrett Nelson ROC^ The Woods and Flora of the Florida Keys: 66Pinnatae”

Introduction logical, and other information has been widely ac- knowledged (Chalk 1944, Heimsch 1942, Keck 1957, The Anacardiaceae, Burseraceae, Meliaceae, Ruta- Stern 1952, Tippo 1946, and others). Comparative ceae, Sapindaceae, and Simaroubaceae constitute a anatomical studies of the secondary xylem of some group of plant families comprising nearly 6,000 or all of the genera treated in this investigation species of pantropical distribution. All are charac- (Dadswell and Eckersley 1938, Dadswell and Ellis terized by plants with pinnately compound leaves. 1939, Dadswell and Ingle 1948, Hess 1946, Heimsch These six families are represented on the Florida 1942, Kribs 1930, Record 1939, 1941, Webber 1936, Keys by at least 15 genera, each has a single species, 1941) indicate that, on the basis of wood anatomy, except for Zanthoxylum, which has two species there. a close interrelationship exists among the members of This investigation is an intensive study of the sec- these six families. Plant taxonomists, using morpho- ondary xylem of these plants (Table 1). According to logical characteristics, have also come to the same Brizicky (1962b, 1963)) Picramnia pentandra Swartz conclusion. However, arrangement of these families (Simaroubaceae) , Melicoccus bijugatus (Sapinda- into orders, based in large part upon such morpho- ceae) , Amyris maritima Jacquin, Zanthoxylum coria- logical characteristics, has been inconsistent. ceum A. Richard, and four naturalized species of Earlier systems of classification, notably those of Citrus in addition to C. aurantiifolia (Rutaceae) are Linnaeus (1753), de Candolle (1824-1873), and also to be found on the Florida Keys but are not Bentham and Hooker (1862-1883), were not based included in this study. Of the plants studied, only on concepts of genetic relatedness as we know them the familial affinity of the genus Suriana has been today. As such, the arrangement of the six families seriously questioned. The assignment of the othzr within these systems is of little interest, other than genera to families has been more or less generally historical. It is not surprising, however, that these accepted. Small (1913) placed the genus Dodonaea families were closely grouped by de Candolle and in his monogeneric Dodonaeaceae. My work has been undertaken to correlate the data derived from Previous numbers in this series appeared in Tropical the Florida Keys members of these six families with Woods (Yale University, School of Forestry) under the data obtained previously by earlier workers, with the running title, “The Woods and Flora of the Florida Keys”: “Introduction” by W. L. Stern and G. K. Brizicky, 107:36- hope that the information gained, although based 65, 1957; “Compositae” by S. Carlquist, 109: 1-37, 1958; on a limited number of genera, will give additional “Goodeniaceae” by W. L. Stern and G. K. Brizicky, 109: insight on the taxonomic relationships of these plants. 38-44, 1958; “Passifloraceae” by W. L. Stern and G. K. The taxonomic usefulness of data derived from Brizicky, 109345-53, 1958; and “Wood Anatomy and study of the secondary xylem of dicotyledons, when Phylogeny of Batidaceae” by J. McLaughlin, 110: 1-15, 1959. “Capparaceae” by W. L. Stern, G. K. Brizicky, and correlated with morphological, cytological, palyno- F. N. Tamolang appeared in Contributions from the United States National Herbarium, 34(2) : 25-43, 1963. Barrett Nelson Rock, Department of Botany, University of These studies were initiated through a National Science Maryland, College Park, Maryland 20742. Foundation grant to William L. Stern in 1955.

1 TABLE1.-Wood specimens of the Florida Keys “Pinnatae” examined

Species Collector and Number Lacation and Herbarium Collection Catalog Number Voucher bcality

ANACARDIACEAE

Metopium taxifem (L.) Kmg & Urban Stern & Brizicky 566 Y Key Largo

Stern 2643b MARY Key Largo

Toxicodendro- radicans (L.) Kuntze Stern 2633 WRY Key Largo BLTRSEPACEAI

--Bursera simaruba (L.) Sarg. Stern & Brizidq 171 Y Big Pim Key Stern 1466 us Windley’s Key

Stern 2624 None Key Largo

!GLIACW

Swietenia mahagani Jacq. Sterr. 2616 .WY Key Largo RUTACEAE

Amyris elernifera L Sterr. & Brizicw 477 Y Key largo

Stern 1455 us Key Largo

Stern 2614 IWY Key Largo citrus aurantiifolia (L.) Swing1e Stern & bizicky 486 Y Key Largo

Stern 2653 hWRY &ey Largo

Zsnthaxylum f- (L.) Sarg. Stern & Brizicky 514 Y Key Largo stern zGn5 IrkRY Key Iaxo

--Z. flavum Whl sterr., 2eam33, PhiE’S, Rock, & Sweitzer 2761, MARY 3ahia Honda Key

SAPINDACEAE

3ar3~0spem:m hslicacabm I,. Stern 2656 MARY Key largo

Cupania glabra Sw. Stern a: Bzizizky 419 Y 3ig Pir.e Key Stern 1506 35 3ig Pke Key stern 2691 MARY Big Pine Key --Dodonaea viscosa (L.) Jacq. stern 128 Y sig Pine Key

Stern & Brizicky 298 Y Big Pine Key

Stern 1513 US Big Pine Key

stern, Beaman, Fhipps,

Rock, & Sweitzer 2735 MARY Big Fire Key

Fxothea paniculata (Ass. ) Radlk. Stern & Brizicky 466 Y Key largo Stern 1467 us Windley’s Key

stern 2612 WRY Key Largo

Hypelate irifoliata Sw Stern a: Brizicky 526 Y Windley’s Key stern 1468 US Windley’s Key stem 2681 .WY Windley’s Key

Sapindus sapanaria L. Stern & Brizicky 552 Y Key largo

Stern 2659 VARY Key largo

SIMeR0UBACEp.E

Simarouba glaucB DC. Stem Brizicky 462 Y Key Largo

Stem 1497 US SiR Pine Key Stern 2613 m Key Largo ~-Suriana maritinla L. Stern & Brizicky 230 Y Big Pine Key stern 1481 US Grassy Key

stern 2666 MARY Big Pim Key

‘Method of citation of wood specimens fallows that recam.e?.ded by Stern 8nd Chanbers (l%C).

hod epecimecs, for which no catalog number is stated, refer to fluid-presemed collectiors 9t the

University of Maryland. NUMBER 5 3

Bentham and Hooker, for the similarity of gross ceae was placed in his Sapindales. Wettstein (1935) morphology is striking. included all six families in his Terebinthales. Engler (Engler and Diels 1936) divided these A survey of recently proposed phylogenetic systems families into two orders : Geraniales and Sapindales. of classification reveals that the treatment of these The Rutaceae, Meliaceae, Burseraceae, and Simarou- families is still not uniform. Cronquist (1968) assigns baceae were placed in the Geraniales; the Anacar- the six “mutually interrelated” families to his Sapin- diaceae and Sapindaceae were placed in the Sapin- dales, citing Heimsch’s work (1942) as a primary dales. Assignment of a family to an order was based reason. Takhtajan (1966) places the Sapindaceae in primarily on the orientation of ovule attachment : his Sapindales, moving the remainder of the families family members with epitropous ovules were placed into his Rutales. Both orders are placed in the super- in the Geraniales, while those with apotropous ovules order Rutinae (which also includes his Geraniales were placed in the Sapindales. The most recent re- and Polygalales). Thorne (1968) places all the fam- vision of Engler’s “Syllabus der Pflanzenfamilien” ilies in his Rutales, grouping the families into sub- (Melchior 1961) redistributes the members of the orders Rutineae (corresponding to Takhtajan’s Ru- Geraniales into a revised Geraniales and a newly tales) and Sapindineae (containing the Sapinda- erected Rutales on the basis of histological differen- ceae). (Table 2 offers a summary of the taxonomic tiation and a trend toward zygomorphy in the flowers. treatment of these six families.) The new Geraniales and Rutales are still segregated Suriana maritima Linnaeus, generally considered from the Sapindales on the basis of ovule attach- within the Simaroubaceae, is seen by Gutzwiller ment. The families concerned with in this study (1961), Jadin (1901), Record and Hess (1943), which were included in the Geraniales are now Small (1911), Thorne (1968), Wilson (1911), and placed in the Rutales. others, as constituting a distinct monotypic family, The phylogenetic schemes used by Hutchinson, the Surianaceae. Cronquist ( 1968) accepts Gutzwil- Hallier, and others, de-emphasized the ovular orien- ler’s exclusion of Suriana from the Simaroubaceae, tation of Engler. Hutchinson (1926) erected three but chooses to place this genus with Stylobasium in orders to account for these families, separating them his (Cronquist’s) Stylobasiaceae. This family is in- largely on the presence or absence of gland-dotted cluded in Cronquist’s Sapindales. On the basis of (pellucid dots) leaves (Figure 5). Those families wood anatomy, Webber (1936) states that such a often having members with gland-dotted leaves were separation of Suriana from the Simaroubaceae is not placed in his Rutales (containing the Rutaceae, Sim- justified. aroubaceae, and Burseraceae) , while those families The distribution and habit of each species dealt without gland-dotted leaves were placed either in with in this study vary widely and are listed sepa- the Meliales or Sapindales. The Meliales (containing rately. Data concerning number of species, distribu- the Meliaceae) is characterized by members having tion, and habit were obtained primarily from Brizicky a stamina1 tube which is lacking in members of the (1962a, 1962b, 1962c, 1963). The species are listed Sapindales (containing the Anacardiaceae and Sap- by family. The collection site of each specimen is indaceae) . All of these orders are within Hutchinson’s indicated in Table 1. arborescent line of evolution. These three orders plus ANACARDIACEAE.Metopium is a genus of three the order Juglandales were grouped by Hutchinson species, occurring in the West Indies, southern Florida in the subphylum “Pinnatae.” The Juglandales was and the Florida Keys, British Honduras, Guatemala, later dropped from this subphylum (Hutchinson and southern Mexico. Metopium toxiferum (L.) 1959). Hallier’s earlier treatment (1905) placed all Krug and Urban, a West Indian species, is found in six families in his large cohort, Rosales, with the the hammocks, pinelands, and coastal dunes in south- note that it would be further subdivided after “. . . ern Florida and the Florida Keys. It occurs as a large more exhaustive examination.” Hallier ( 1912) later tree in the hammocks and as a shrub in the pinelands combined the members of the Anacardiaceae and throughout the Florida Keys. Burseraceae into a single family, the Terebinthaceae, Toxicodendron is a largely north temperate zone which he included in his Rutales, along with Ruta- genus of approximately 15 species of North American ceae, Meliaceae, and Simaroubaceae. The Sapinda- and eastern Asiatic distribution. Toxicodendron ra- 4 SMITHSONIAN CONTRIBUTIONS TO BOTANY

TABLE2.--Com~arison of taxonomic treatments

hgler (Melchior 19647 Hutchinson (1959) Tskhtajan (1966) Thorne (1968)

Order Sapindales lrder Rutalesb ,ubphylw,. HcnataeC superorder Rutinae' luperarder. Rutiflarse

Stylabasiaceae' Suborder Rutineae Order. Rutales Order Rlteles Order Futales

Sapindaceae Rutaceae Futaceae Anacaraiaceae Suborder. Rutineae

Furseraceae Simaroubaceae Simaroubaceae Burseraceae Rutaceae

Anacardisceae Eurseracese Bursereceae Sinaroubaceae SLmaroubaceae

Simaroubaceae Meliaceae Order Meliales Rutaceae surianaceae

Rutaceae kder Sapindales Meliaceae Meliaceae Meliaceae

Meliaceae Suborder Anacardineae Order Sapindales Order %piridales 3;rseraceae

hacardiaceae Sapindaceae Sapindaceae hacardiaceae

Suborder Sapindineae Anacardiaceae Suborder. Sapindineae

Sapindsceae Sapindaceae

aInc1uaes -

this most recent revision of Engler's system (Melchior l%k) the older Geraniales has been subdivided

into a revised Ceraniales and B newly erected Rutales (containing those families listed above in addition to

others 1.

'This subphylum previously included the order Juglandales (1926 ). 'ffeviously the silperorder Einnatae . dicans (L.) Kuntze (Figure 1) is widely distributed elemifera Linnaeus is primarily a West Indian species, in woods, thickets, fencerows, and swamps through- occurring also in southern peninsular Florida and the out most of southern Canada, the United States, Florida Keys. It ranges in habit from a shrub to a northern Mexico, and the West Indk2 It occurs small tree (up to 50 feet tall, with trunks up to a as a woody vine throughout its range. foot in diameter), and occurs in the hammock BURSERACEAE.Bursera is a genus of approxi- forests throughout the Keys. mately 100 species, distributed throughout tropical Citrus is a highly polymorphic genus with an and subtropical America. Bursera simaruba (L.) uncertain number of species (16 minimum and Sargent (Figures 2, 3) is found in southern Florida possibly 145 maximum, Brizicky 1962a), native to and the Florida Keys, the West Indies, southern southern and southeastern Asia and Malaysia. Sev- Mexico, Central America, and northern South Amer- eral species are widely cultivated and have escaped ica. It occurs as a large tree, primarily in the ham- to all warm regions of the world (Brizicky 1962a). mock forests throughout the Florida Keys. Five species are recorded as more or less naturalized MELIACEAE.Swietenia, a genus of at least three throughout southern Florida and the Florida Keys. species, occurs in southern Florida and the Florida Citrus ourantiifolia (L.) Swingle, the lime (the Keys, the West Indies, Mexico, Central America, single species of Citrus collected), is a tree native Colombia, Venezuela, and the upper Amazonian to the East Indian Archipelago. It occurs on the region. Swietenia mahagoni Jacquin (Figure 4) is Florida Keys along roadsides and in secondary woods found in the West Indies, southern Florida and the (hammock forests). Florida Keys. On the Florida Keys it occurs in the Zanthoxylum, a genus of some 215 species, is hammock forests. It is a large tree throughout its mainly pantropical in distribution (Brizicky 1962a), range. with several species extending into temperate North RUTACEAE.Amyris is a genus of approximately America and eastern Asia.3 Both of the species en- 20 species, occurring in southern Florida (including the Florida Keys) and Texas, the West Indies, Cen- 'According to Record and Hess (1943), the genus tral America, and northern South America. Amyris Zanthoxylum comprises only 15 species, all of north-tem- perate distribution, while the genus Fagara comprises ap- Toxicodendron is recognized as distinct from Rhus, proximately 200 pantropical species. Brizicky ( 1962a) con- primarily on the basis of Barkley's monograph (1937). siders Fagara as a synonym for the older Zanthoxylum. NUMBER 5 5 countered in this study are considered native to the in the hammock forests and adjacent pinelands of the West Indies (Brizicky 1962a). Zanthoxylum fagara Florida Keys. (L.) Sargent occurs in central and southern Florida, Exothea is a tropical American genus of three spe- including the Florida Keys, southern Texas, the cies, ranging from the West Indies, southern Florida, West Indies, Mexico, Central America, and South Mexico and Central America, south to Costa Rica. America. It occurs as an armed (spined) shrub oi Exothea paniculata (Jussieu) Radlkofer occurs as a small tree throughout its range. Zanthoxylum flavum small tree in the hammock forests and on calcareous Vahl occurs as an unarmed small tree on the lower soils and shell mounds in southern peninsular Florida, Florida Keys (specifically Bahia Honda Key State the Florida Keys, the West Indies, and Guatemala. Park) and the West Indies. Both species occur in Hypelate, a genus comprising a single species, H. hammock forests. trifoliata Swartz, occurs as a shrub or small tree in SAPINDACEAE.Cardiospermum, a genus of ap- the hammock forests (and rarely the pinelands of proximately 12 species, is primarily of tropical Big Pine Key) of the Florida Keys and the West American distribution, with one species occurring in Indies. tropical West Africa and one ill-defined species Sapindus is largely a tropical genus of approxi- (Cardiospermum halicacabum L.4) of pantropical mately 13 species, three of which are distributed in distribution. Cardiospermum halicacabum (Figure 8), the Americas, with the remainder found in eastern a woody perennial vine, occurs in the hammock and southeastern Asia, Oceania exclusive of Austra- forests on the Florida Keys. lia, and Hawaii. At least two of these species are Cupania is a tropical American genus of approxi- extratropical. The primarily tropical American spe- mately 45 species and extends from Argentina and cies, S. saponaria Linnaeus (Figures 6, 7), occurs as Peru north to Mexico and into southern Florida, the a tree from Argentina, north into Mexico, the West Florida Keys, and the West Indies. Cupania glabra Indies, southern Florida, and the Florida Keys. It Swartz (Figure 9) occurs in the West Indies, the is a member of the hammock forest flora on the Florida Keys, Mexico, and Central America as far Florida Keys. south as Costa Rica. It is a small tree of the ham- SIMAROUBACEAE.Simarouba is a widely distrib- mock forests, occurring in Watson’s Hammock on uted tropical American genus comprising from six Big Pine Key. to nine species. Sirnarouba glauca DeCandolle (Fig- Dodonaea is primarily an Australian genus of ap- ure 10) occurs as a tree in southern Florida and the proximately 60 species. One species occurs in Mada- Florida Keys, the West Indies, southern Mexico, gascar, three occur in Hawaii, and one [Dodonaea Central America, and part of South America. It is viscosa (L.) Jacquin] is reported as pantropical in an inhabitant of the hammock forests on the Florida distribution. Dodonaea viscosa5 occurs as a small tree Keys. Suriana is a monotypic genus of pantropical dis- ‘ The treatment of the species Cardiospermum halicaca- bum accepted in this study is as follows: C. halicacabum tribution. The single species, S. maritima L. (Figure comprises at least three varieties-halicacaburn, microcarpum 11) is a small to large shrub (occasionally a small (syn. C. microcarpum H.B.K.), and corindum (syn. C. tree) of the strand vegetation, occurring along sea- corindum L.; C. keyense Small)-each of which is con- coasts throughout its range. sidered by some authors (Brizicky 1963) as constituting a separate pantropical species. All three varieties are reported as occurring on the Florida Keys. Materials and Methods ‘Brizicky (1963) refers to the pantropical species as Dodonaea viscosa (L.) Jacquin, noting that this species in- Specimens studied in this investigation are listed in cludes D. jamaicensis de Candolle and D. microcarya Small, Table 1. Dried wood specimens were obtained from tentatively accepting SherfT’s concept of a single species Dr. William L. Stern. Specimens bearing catalog (D. viscosa) having three distinct pantropical varieties. Sherff asserts that all of these varieties occur in Florida. numbers of the Record Memorial Collection, Yale Brizicky states, however, that inadequate data make “. . . im- University School of Forestry (YW)~,and the Na- possible any conclusion regarding the nature and delimita- tion of infraspecific categories of D. uiFcosa.” Therefore, ‘The Samuel James Record Memorial Collection, origi- throughout this paper, the Florida Keys Dodonaea is refer- nally housed at the Yale University School of Forestry, was red to as D. viscosa. transferred to the U.S. Forest Products Laboratory in Mad- 6 SMITHSONIAN CONTRIBUTIONS TO BOTANY tional Collection of Woods, Smithsonian Institution ments were made from macerated material. Measure- (USw), were available as prepared slides. In addi- ments of pore distribution, pore diameter, and end tion, fluid-preserved specimens bearing Stern collec- wall angle were made from sectioned material. All tion numbers 2612 through 2764 were utilized (see measurements are recorded in microns (p). Table 1). All wood samples were collected from Fibrous elements were measured using a Bausch mature stems and are documented with herbarium and Lomb Tri-Simplex microprojector, except in a vouchers, with the exception of Bursera sirnaruba few cases where, because of cellular breakage, accu- Sargent, Stern 2624. rate measurement required the higher magnification Microscope slides of specimens bearing Yale or and resolution available only through the use of a Smithsonian catalog numbers had been previously compound microscope. Vessel element lengths were prepared from unembedded, dried wood samples. measured with both the microprojector and the The fluid-preserved specimens were embedded in microscope, the latter was used when the small size celloidin prior to sectioning. All slides prepared spe- of the vessel elements prohibited accurate measure- cifically for this study from fluid-preserved material ment on the projector. The total length (tail to tail) collected by Stern were sectioned on a sliding micro- of vessel elements was measured, following the sug- tome. All transverse sections were cut at 20p, while gestions of Chalk and Chattaway (1934, 1935). radial and tangential sections were cut at 15p, 20p, Tangential pore diameters were measured from and 30p to provide different thicknesses for optimum outside wall to outside wall. Only solitary pores were study of all cells and tissues. The sections were measured except in species where, because of the low stained in safranin and Heidenhain’s iron-alum percentage of solitary pores, measurement of the tan- haematoxylin, dehydrated and cleared following gential diameters of pores arranged in radial multiples standard microtechnical procedures, and mounted in was required. Pore distribution was determined from Canada balsam. Exceptionally hard woods were soft- transverse sections, while vessel element end wall in- ened prior to sectioning, either in hydrofluoric acid, clination was measured on tangential sections. as outlined in Sass (1958), or by boiling in Aerosol In measuring the lengths of the fibrous elements OT solution in a reflux apparatus (a modification of and vessel elements, pore diameter, and inclination the procedure outlined by Ayensu 1967). of vessel element end walls, a total of 50 random Macerations were prepared following a variation of measurements of each character was made for each Jeffrey’s method. The original method, outlined in species. From these measurements, a range, a most Johansen ( 1940), was modified in the following man- frequent range (within which at least 50 percent ner: tertiary butyl alcohol was used as the dehydrant of the measurements made occur; hereafter abbre- and, upon complete dehydration, a small amount of viated MFR) , and a mean (average) were calculated, stained cellular material was taken directly from the except for the inclination of end walls, where only tertiary butyl alcohol and placed into a watch crystal a mean was calculated. containing a mixture of xylene and Canada balsam Pore distribution was determined by recording the of mounting consistency. The mass of cellular mate- total number of solitary pores, radial multiples, and rial was then spread throughout the mounting me- pore clusters seen in a given field of view. Ten fields dium by gently mixing with a glass rod. A few drops were observed, and the total number of pores in of this mixture were then placed on a microscope each distribution type was converted to a percentage slide and a cover slip added. of the total number for all categories. In members Selection of the diagnostic characters to be included of the Rutaceae, pore chains in addition to radial in the descriptions of each species was made from multiples are observed. Because of intergrades be- those suggested by Tippo (1941). Measurements of tween chains and multiples, and the difficulty in dis- the length of both fibrous elements and vessel ele- tinguishing between each type, the pores of either type are reported only as radially oriented (Table ison, Wisconsin, in December 1969. It is distinguished from 3). other wood collections in the Laboratory through the abbre- The terminology used in this investigation generally viation SJRw. Original wood collections at the Laboratory bear the abbreviation MADw ; the Record Collection for- follows that suggested by the Committee on Nomen- merly carried the abbreviation Yw. clature, International Association of Wood Anato- NUMBER 5 7

TABLE3.-Pore arrangement, diameter, and wall thickness

DISTRIBUTION (percent) POFE -D IETER SFZCIES Radially Solitary mltiples Clusters Av g Range m 1 Rangeo Oriented -

ANACARDIACEAE Metopiwn toxiferum 67 78 40-110 55-90 2-7

Taxicodendran radicans 80 52 15-110 2C-75 1-5

SWSERACE.45

-__Bursera sinaruba 70 88 45-110 83-105 1-3 MELLACEAE

Swietenia mahagoni 68 -36 65-220 too-163 3-8

RLTTACEAI

Amyris elemifera 53 53 30-55

Citms auranriifolia 70 78 30-110 65-10c 4-8 Zamhoxylum fasara 5542 63 30-100 45-85 2-12

--2. flwm 58 40-85 50-7C 2-7 SAPIhQACEAE

Cardiospermum halicacaburr. 75 3Zd 20-50 4-13 -02 60-145 83-125

Cupsnia glabra 35 78 30-105 75-95 2-7 --Cadonaea viscasa 43 72 50-100 60-90 3-7 Exathea paniculata 50 71 50-95 60-85 2-8 Hypelate trifoliata 59 58 3C-80 45-73 3-7

Sapindus saponaria 78 99 40-150 85-110 2-5 SIMAROUBACEAE

Simarouba glauca 40 -75 85-260 --Suriana maritime. 41 58 30-85 -

’Numbers in parentheses indicate the range of the number of pores Pound in each category.

balls between pores in .radial multiples and clusters are the thickest.

CPore distribution reported a8 “radially oriented” because Of difficulty in differentiating between

radial multiples and chains. Gxly in the case of Amyris elemifera are the majority of the radially

oriented pores in distinct chains.

dSmall pores (see description). mists, International Glossary of Terms Used in Wood cheids or libriform wood fibers, because of the tenuous Anatomy (1957), hereafter referred to as the IAWA nature of the pitting encountered in the species Glossary. General terms used in describing relative studied. sizes of structures (e.g., intervascular pit sizes and In describing the simple pits commonly found in fibrous element, cell wall thickness) are those sug- the parenchymatous cell types encountered in the gested by Record and Chattaway (1939). woods under study, the term “fenestriform” is used. The terms “fibrous elements” and “imperforate This term, meaning “windowlike,” is used to describe tracheary elements” are used here interchangeably any enlarged, oval to rectangular pit. These enlarged and refer to the prosenchymatous cell types commonly pits are considerably broader than the intervascular referred to as “fibers.” No attempt was made to pits in the species being described. The fenestriform designate such fibrous elements as either fiber-tra- pits most frequently seen in this study are the en- larged simple components of a half-bordered, vessel ‘ In the parlance of “wood technology” and “forest products,” “fibers” also include the tracheids of gymno- to parenchyma pit-pair. In some species both com- sperms. ponents of vessel to parenchyma pit-pairs are fenestri- 8 SMITHSONIAN CONTRIBUTIONS TO BOTANY

form in nature. Since the simple fenestriform pits are radicans both components of vessel to parenchyma generally larger than the bordered pit of a half- pit-pairs are commonly fenestriform (Figure 32). bordered pit-pair, a single fenestriform pit will fre- Unilaterally compound vessel to parenchyma pitting quently subtend two or more bordered pits, resulting occurs in all species. in unilaterally compound pitting. The fibrous elements of all species studied have Because of the ambiguity, awkwardness, and lack oval to slitlike simple or slightly bordered pits pre- of precision involved in employing only names to dominating on their radial walls (Figures 28, 29). categorize vascular rays (Kribs 1935), a description The slitlike inner apertures of any given pit-pair may of the ray tissue of each species is given. The terms be either crossed at angles to one another, or directly “homocellular” and “heterocellular” are used in the superposed. Both configurations are frequently ob- literal sense. Rays comprising only a single cell type served on a single specimen. Axial parenchyma is (for example, a ray which consists only of procumbent present in all species. Vascular tracheids and dis- cells) are referred to as homocellular. A ray con- junctive paratracheal parenchyma cells are found in taining two or more cell types, even though one type all species. may be of only rare occurrence, is referred to as heterocellular. Since varying degrees of the hetero- ANACARDIACEAE cellular type of ray occur in the woods studied, refer- ence to the predominant cell type or types is given Metopium toxiferum (L.) Krug and Urban: Faint in each description. growth rings are present. The pores are angular In the following anatomical descriptions, charac- to rounded, with vessel element walls varying in ters common to all the species studied are included thickness from 2p to 7p. in an initial description. The descriptions of the in- Vessel element length averages 375p, with a range dividual species which follow this are arranged ac- of 19Op to 670p and a MFR of 330p to 450p. Per- cording to family. The arrangement of both families forations are simple, with the single exception of a and the genera within each family is alphabetical. multiple perforation observed in maceration. The Table 3 contains numerical data concerning the pore arrangement of perforations in this instance is such distribution, pore diameters, and vessel wall thickness that neither the term reticulate nor foraminate is of each species. Table 4 is a summary of pertinent accurately descriptive. It should be noted that be- anatomical data obtained from each species and is cause of the fenestriform nature of vessel wall pits included in order to facilitate comparison. involved in vessel to parenchyma .pitting, description of this perforation plate as multiple may not be ac- curate. The structure seen may actually be a collec- Anatomical Descriptions tion of such fenestriform vessel wall pits, arranged of the Woods of “Pinnatae” at the end of the vessel element in such a manner that Where growth rings are present, the wood in all the impression of a multiple perforation is given. specimens studied is diffuse-porous (Figure 16), with Vessel element end walls are inclined at an average the exception of Toxicodendron radicans, which is of 44’. In general, the vessels are ligulate. questionably diffuse-porous (Figure 19) . All perfora- Intervascular pitting comprises medium-sized pits tions are simple (Figure 32), with the exception of ranging from 7p to lop in diameter. Pit borders are a single multiple perforation observed in Metopium round to somewhat angular; pit apertures are oval toxiferum. and included within the borders. Intervascular pitting is alternate in all species Both vessel to axial parenchyma pitting and vessel (Figures 30, 31 ) . Scalariform-like intervascular pit- to ray parenchyma pitting are fenestriform in nature, ting produced by coalescence of adjacent pits and both members of a vessel to parenchyma pit-pair are unilaterally compound intervascular pitting (Figure oval to somewhat angular and simple. 31) occur to some extent in each species. Fenestri- The imperforate tracheary elements are nonseptate. form pits occur in the axial parenchyma and ray Fibrous elements are gelatinous in nature (Figure 34), parenchyma of each species, while in Bursera sima- and, as such, two measurements of wall thickness ruba, Metopium toxiferum, and Toxicodendron were made. The rigid lignified portion of the sec- NUMBER 5 9 ondary wall is from lp to 3p thick while the com- localized banding. All the axial parenchyma cell bination of rigid and nonrigid secondary walls seldom types frequently contain starch grains. Crystalliferous exceeds 6p. As such, the wall thickness (combined) strands are absent. ranges from thin to very thick. The average length Thin-walled tyloses are seen extending into the of the fibrous elements is 683p, with a range of 330p vessels from both axial and ray parenchyma (Figure to 970p and a MFR of 560p to 860p. 34). In longitudinal section, a high percentage of the Vascular rays are predominantly bi- and triseriate. fenestriform vessel to ray pits are sites of tylosis for- Some uniseriates are present and a few rays up to mation. five cells wide are seen. These may contain horizontal Toxicodendron radicans (L.) Kuntze : The wood intercellular canals. All rays are heterocellular, com- is diffuse-porous (Figure 19), although the outer prising upright, square, and procumbent cell types. growth rings tend to be ring-porous ; faint growth rings The bi- and triseriate rays frequently possess uniseri- are present. The pores are circular to somewhat ate wings of from 2 to 4 rows of square and upright angular, with walls ranging in thickness from lp to cells, or both, the remainder of the ray comprising 5p. Tangential pore diameters range from 15p to procumbent cells. Many of the uniseriate rays appear 11Op. A study of macerated material, however, re- to be composed largely of square and upright cells, veals a number of smaller vessel elements, having or both. The uniseriate rays range from 1 to 8 or diameters of less than 15p (as measured on macerated more cells in height, while the bi- and triseriate rays material). These vessels could not be included in the are up to 20 cells (400p) or more in height. Starch measurements of diameters in transverse section, be- occurs in many of the ray cells. cause they are not readily distinguishable from im- The horizontal intercellular canals seen in the rays perforate tracheary elements. of this species are of infrequent occurrence in Stern Vessel element length averages 250p, with a range 2643, but rather frequent in Stern @ Brizicky 556. of 120p to 360p and a MFR of l60p to 300p. Vessel The canals are surrounded by an epithelial lining (1 element end walls are inclined at an average of 41°. to 2 cells thick) composed of small, square to angular The vessel elements are generally ligulate. cells with thin isotropic (optically inactive) cell Intervascular pitting comprises small bordered pits walls. The cells external to the epithelial lining are ranging in size from 4p to 6p in diameter. The pits, of similar shape and size, but with somewhat thicker, generally restricted to the ends of the vessel elements optically anisotropic cell walls. These cells tend to (pitting on the body of the vessel elements is rela- intergrade with the larger, typical procumbent cells. tively infrequent, because of the high percentage of The canals seen in Stern 2643 are apparently at an solitary pores) , possess circular to lenticular apertures early stage of development, possessing small inter- included within rounded to angular borders. cellular spaces or canals, while those seen in Stern Vessel to axial parenchyma pitting comprises half- @ Brizicky 556 are of a later stage of development, bordered to simple pit-pairs. The component pits having massive intercellular spaces or canals. Many of a simple pit-pair, in the vessel element wall and of these older canals lack any organized epithelial the axial parenchyma wall, are both fenestriform in layer (apparently due to lysigeny). In the latter nature. Half-bordered pit-pairs are rather infrequent, specimen, the canals are often nearly as wide as the the bordered pit of the vessel element wall generally ray in which they occur. In both specimens a dense, having large lenticular apertures extending to lentic- rather darkly staining substance is found in many of ular borders. These bordered pits are generally larger the canals, in addition to remnants of epithelial cell than the intervascular bordered pits and intergrade walls. It is apparent that these canals are secretory with the fenestriform simple vessel element pits. Ves- in nature. sel to ray parenchyma pitting is very infrequent. Axial parenchyma is present in both apotracheal When present, it resembles the vessel to axial paren- and paratracheal arrangements. Apotracheal paren- chyma pitting. chyma forms irregularly spaced bands which vary in The imperforate tracheary elements are septate, width from 1 or 2 cells to 10 or more cells wide. each cell having a single septum. Fiber walls vary Bands are independent of growth rings. Paratracheal in thickness from 1p to 5p and range from very thin parenchyma is aliform to confluent, leading to some to thick. A study of macerated material reveals that 10 SMITHSONIAN CONTRIBUTIONS TO BOTANY the fibrous elements may have either attenuated or Vessel element length averages 531p and ranges truncate end walls. Fibrous elements contain mas- from 300p to 770p; the MFR is 495p to 700p. Ves- sive amounts of starch. The average length of the sel element end walls are inclined at an average of fibrous elements is 374p, with a range of 230p to 560p 48'. The vessels may be either ligulate or eligulate. and a MFR of 300p to 440p. Intervascular pitting comprises medium-sized pits Vascular rays are uniseriate and biseriate, although ranging from 7p to lop in diameter. The pit aper- in some cases, a portion of a biseriate ray may be up tures are lenticular and included within polygonal to three cells wide. Square and upright cell types pit borders. occur most frequently, while the procumbent cell Vessel to axial parenchyma pitting is rare because type is rare. The cell type found in any given horizon- of the scarcity of paratracheal parenchyma. Where tal row is frequently constant, with one row composed it occurs, it is sporadic and irregular to alternate entirely of upright cells while another is composed and larger than the intervascular pitting. Vessel to of square cells. The occurrence of two cell types ray pitting differs from the above in that it is var- within the same horizontal row is relatively infre- iable in form, ranging from large, generally rectangu- quent. Arrangement of cell types does not follow a lar fenestriform pits to small, oval pits (Figure 32). pattern. The uniseriate rays vary in height from 2 Both components of the former type of vessel to ray cells to 30 cells or more. Approximately 50 percent parenchyma pit-pair are fenestriform in nature. Both of the ray cells contain a dark-staining substance of vessel to axial parenchyma pitting and vessel to ray unknown composition. Ray cells generally contain parenchyma pitting are half-bordered. large amounts of starch. The imperforate tracheary elements are septate, Axial parenchyma is present in both apotracheal having from 3 to 8 septa per cell, 3 being the most and paratracheal arrangement. Diffuse parenchyma common. Fibrous elements in Stern 2624 contain apparently comprises noncrystalliferous strands. Since massive amounts of starch (Figures 12, 13) ; starch the fibrous elements of this species are living (septate grains are also seen in Stern 1466. Wall thickness of and store starch), it was difficult to determine wheth- fibrous elements may be classified as very thin, 2p to er cells, seen in either transverse or longitudinal sec- 4p thick. The average length of the fibrous elements tion, were axial parenchyma cells or fibers. Since is 809p, the range 440p to 116Op and the MFR 730p the other parenchymatous cells (paratracheal paren- to 950p. chyma and ray parenchyma) frequently contained a Vascular rays are predominantly multiseriate ; some dark-staining substance, this character was used as uniseriate and biseriate rays are seen. All rays are the distinguishing criterion ; cells containing the dark- heterocellular, although some of the uniseriate rays stained substance, when viewed in transverse section, appear to be homocellular when seen in tangential were interpreted as diffuse parenchyma. The para- section. A survey of 10 radial sections, however, did tracheal parenchyma is scanty vasicentric to vasi- not reveal such homocellular rays. This is apparently centric, and, as mentioned previously, frequently con- related to the nature of cell arrangement. In radial tains a dark-staining substance similar to that seen section, there are no horizontal rows consisting of in the ray tissue. only one type of ray cell. Those rows containing A large number of small, thin-walled tyloses are procumbent cells also contain square and upright present in many of the vessel elements. The tyloses cells, or both. Tangential sections of the same ray contain the dark-staining substance seen in the para- taken at different points would appear to be homocel- tracheal parenchyma cells. This is to be expected, lular at one point and heterocellular at the other. The since tyloses are extensions of parenchyma cells into height of the uniseriate rays is up to 350p (20 cells). the vessel lumen. These are far less frequent in occurrence than are the multiseriate rays. Multiseriate rays are up to 500p (30 cells) in height BURSERACEAE and up to loop in width. The body of the multiseri- Bursera simaruba (L.) Sargent: Growth rings are ate ray is composed of procumbent cells. These rays absent. The pores are somewhat angular and have generally have uniseriate wings, 1 to 3 cells high, walls lp to 3p thick. composed of upright and square cells, or both. The NUMBER 5 11

rows of procumbent ray cells are uniform, as is gen- parenchyma pitting are half-bordered. The bor- erally true of the rows of upright and square cells dered pits of the vessel wall are arranged in an of the vertical wings. The upright and square ray alternate pattern, these pits coinciding in shape and cells of this ray tissue frequently contain optically size to intervascular pits. The simple pits of the anisotropic, prismatic crystals and starch grains. parenchyma walls are oval to elongate and often Horizontal intercellular canals are seen in many fenestriform in nature. of the multiseriate rays (Figure 24). These canals Imperforate tracheary elements are septate, having are circular in cross section (as seen in tangential a wall thickness that varies from 2p to 7p, and ranges section) and surrounded (lined) with thin-walled from thin to thick. Septa are thin and there are epithelial cells. The walls of the epithelial cells are two per cell. The average length of the fibrous ele- optically isotropic (optkally inactive when viewed ments is 981p, with a range of 650p to 1250p and a under crossed nicols) . MFR of 880p to 1160p. The arrangement of axial parenchyma is difficult The vascular rays are uniseriate to multiseriate, to determine, because of the difficulty in distinguish- with rays infrequently up to five cells wide; 3- and ing between axial parenchyma cells and the thin- 4-seriate rays are the most frequent. All rays are walled, septate, living fibrous elements. As mentioned heterocellular. The infrequent uniseriate rays are previously, the fibrous elements store starch and, as short, ranging from a single cell to eight or more cells such, carry on one of the functions of axial paren- in height, and composed almost entirely of square chyma. Determination of the presence of axial paren- and upright cells, or both. Biseriate rays are longer chyma was made only through study of macerations. than uniseriate rays, ranging from 5 to 15 or more Distinction between fibrous elements and axial paren- cells in height, and composed of the same cell types chyma cells in macerated material was based on the seen in the multiseriate rays. Multiseriate rays range pitting and on the cell wall configuration: the trans- in height from 10 cells (250p) to 30 cells (700p) verse, truncate, horizontal end walls of the paren- or more, the longer rays generally resulting from chyma cells and the septa of the attenuated fibers. vertical fusion of two rays. Bi- and multiseriate rays The axial parenchyma seen in macerations may be comprise procumbent, square, and upright cell types. classified as scanty vasicentric. Apotracheal paren- The procumbent cell type generally makes up the chyma may also be present but is not distinguishable multiseriate portion of a given ray, while the square in transverse section. and upright cell types comprise the one- to many- celled uniseriate wings or margins (Figure 22). Many ray cells contain an opaque, dark-staining substance MELIACEAE of unknown composition. Most ray cells contain Swietenia mahagoni Jacquin : Growth rings are starch. Marginal cells are frequently crystalliferous present. Pores are rounded to somewhat angular with idioblasts. The ray tissue is storied. vessel element walls varying in thickness from 3p Axial parenchyma occurs in both apotracheal and to 8p. paratracheal arrangement. Apotracheal parenchyma Vessel element length averages 437p, with a range is present mainly as marginal bands (initial). Some of 200p to 720p and a MFR of 390p to 515p.. Ves- diffuse parenchyma is also present. Both types of sel efement end walls are inclined at an average of apotracheal parenchyma cells contain starch; either 62'. Vessel elements may be either ligulate or eligu- may be crystalliferous, the occurrence of crystal- late. liferous idioblasts is infrequent and random. Crystal- Intervascular pitting comprises minute bordered liferous strands are not present. The paratracheal pits ranging in size from 2p to 3p in diameter. Pit parenchyma is scanty vasicentric to vasicentric. Both borders are rounded to angular; pit apertures are types of axial parenchyma cells frequently contain lenticular to oval and are included within the bor- the same dark-staining substance reported in the ray ders. cells. Vessel to axial parenchyma pitting and vessel to Vessels generally contain this dark-staining opaque ray parenchyma pitting are very similar in size, substance also. The vessel elements tend to be storied shape, and arrangement. Both types of vessel to in addition to the rays. 12 SMITHSONIAN CONTRIBUTIONS TO BOTANY

RUTACEAE are present. The pores are circular, with walls rang- ing from 4p. to 8p thick. Radial multiples are the Amyris elemifera Linnaeus: Growth rings are pres- predominant, radially oriented, pore group. ent, but not distinct. Pores are rounded in cross sec- Vessel element length averages 273p, with a range tion, and have walls 4p to 8p thick. Chains are the of 150p to 420p and a MFR of 235p to 340p. Ves- predominant, radially oriented, pore group. sel element end walls are inclined at an average of Vessel element length average 250~,with a range 58’. Vessel elements may be ligulate or eligulate. of 110p to 350p and a MFR of 220p to 330p. Ves- sel element end walls are inclined at an average of Intervascular pitting consists of small pits, ranging from 4p to 6.p in diameter. Pit apertures are rounded 55’. The vessel elements are generally ligulate. to oval and included within round to polygonal bor- Intervascular pitting comprises minute bordered ders. pits ranging from 3p to 4p in diameter. Pit apertures are slitlike to oval and included within the circular Vessel to axial parenchyma pitting is alternate. pit borders. Vessel to axial parenchyma pitting is rare, The pits found in the vessel element walls are similar owing to the scarcity of paratracheal axial paren- in size to intervascular pits, while those found in the chyma; where it occurs, it is alternate. Vessel to ray axial parenchyma walls are larger and simple. Ves- parenchyma pitting is alternate. In both types of ves- sel to ray parenchyma pitting is alternate and resem- sel to parenchyma pitting, the pit-pairs are half- bles the vessel to axial parenchyma pitting. bordered; the vessel pits are similar in size and shape Fibrous elements are nonseptate, having thin walls to the intervascular pits described above, and the from 2p to 5.u thick. The average length of the parenchyma pits are fenestriform and simple. fibrous elements is 752p, with a range from 400p to Imperforate tracheary elements are nonseptate, 1150p and a MFR of 560p to 890p. having thick cell walls 3p to 7p in thickness. The Vascular rays are uniseriate to triseriate, some rays aveage length of these fibrous elements is 443p, with rarely 4 cells wide. The uniseriate rays range from 1 a range of 270,~to 660p and a MFR of 375p to 5301. to 12 cells (150p) in height and are heterocellular. Vascular rays are uniseriate and homocellular, all The biseriate and triseriate rays are up to 40 cells cells are procumbent. Although the orientation of (500p) in height and are heterocellular, a few hav- individual ray parenchyma cells is horizontal in all ing uniseriate wings of from 1 to 4 cells high. In cases, cell length varies, and in some instances, some the case of both uniseriate and multiseriate rays, the cells in a horizontal row are nearly square. However, great majority of cells are procumbent. Very few since these “square” cells are not a consistent charac- upright cells were seen in the material studied, ar- ter, either in their occurrence or their arrangement, rangement of the cell types follows no pattern, and I feel the designation of “homocellular” is justified. although the margins of the multiseriate rays may Rays average from 3 to 10 cells in height, rarely up be a mixture of procumbent and square cells, the to 19 cells (200p) high. body of the ray comprises only procumbent cells. The Axial parenchyma is present as diffuse and banded ray cells in contact with vessel elements are frequent- apotracheal parenchyma and as scanty paratracheal ly disjunctive. Most ray cells contain starch grains. parenchyma. The banded apotracheal parenchyma is Axial parenchyma is present in both apotracheal 1 to 3 cells wide and continuous; the diffuse paren- and paratracheal arrangements. The apotracheal chyma is present as crystalliferous strands compris- parenchyma is banded, diffuse, and diffuse-in-ag- ing 2 to 8 cells (as viewed in tangential section). The gregates, some of which comprise crystalliferous crystalliferous parenchyma cells (idioblasts) are strands of from 3 to 20 cells. The banded apotracheal much enlarged. No starch grains were seen, because parenchyma is made up of axially elongate paren- of the acid-softening treatment. chyma strand cells, some of which have further sub- Small thin-walled tyloses are present (Figure 33) . divided and are crystalliferous (crystalliferous An amorphous material is seen in some vessels, per- strands). Many of the cells of the diffuse and dif- haps because of gummosis of the parenchyma cells fuse-in-aggregates parenchyma are crystalliferous. forming the tyloses. The crystalliferous idioblasts are generally much en- Citrus aurantiifolia (L.) Swingle: Growth rings larged, containing optically anisotropic prismatic NUMBER 5 13 crystals (Figure 25). The bands of axial parenchyma uniseriates, ranging up to 400p (30 cells) or more are from 1 to 4 cells wide and are continuous. Para- in height, the biseriate portion of the ray is typically tracheal parenchyma is scanty vasicentric and some- composed of only procumbent cells, while the uniseri- times aliform. Axial parenchyma cells are frequently ate margins or “wings” are composed of 1 to 5 or disjunctive. Most, if not all, of the axial parenchyma more horizontal rows of square and upright cells, or cells contain starch. both. Starch is not present in the ray cells, possibly The vessels often contain a granular to non- because of the hydrofluoric acid treatment of the granular, translucent amorphous material aggregated specimen (Stern 2625) prior to sectioning. on or near the perforation plates. Axial parenchyma is present in apotracheal and Zanthoxylum fagara (L.) Sargent : Faint growth paratracheal arrangement. The apotracheal paren- rings are present. Pores are circular, with walls rang- chyma occurs as continuous bands, ranging from 2 to ing in thickness from 2p to 12p. Radial multiples 7 or more cells in width, comprising strand paren- are the predominant radially oriented pore group chyma. Generally there are two cells per strand, al- (Figure 14). though in some cases, one or both of these cells has Vessel element length averages 261p, with a range further subdivided several times, giving rise to short of 145p to 465p and a MFR of 210p to 310p. Ves- strands of crystalliferous idioblasts. Scanty diffuse sel element end walls are inclined at an average of parenchyma comprises the same cell type as described 64’. Vessel elements may be either ligulate or above. The paratracheal parenchyma is scanty vasi- eligulate. centric. Intervascular pitting comprises minute bordered Irregular and continuous periclinal cavities occur pits ranging from 2p to 3p in diameter. Pit apertures throughout the xylem of Stern 2625 (Figures 26, 27). are oval to lenticular and included within rounded These cavities are apparently traumatic in origin and borders. contain an evenly staining, homogeneous, opaque to Vessel to axial parenchyma pitting and vessel to transparent substance. Many of the vessels contain ray parenchyma pitting are similar in size, shape, a granular to nongranular (similar in appearance to and arrangement. The pit-pairs are half-bordered, the homogeneous material seen in the traumatic with the bordered vessel element pits similar in size, cavities described above) , translucent to transparent shape, and arrangement to the intervascular bor- material. dered pits described above. The simple parenchyma Zanthoxylum flavum Vahl: Growth rings are pits (both axial and ray parenchyma) are generally present. Pores are circular to somewhat angular, with circular to oval and are either approximately the the vessel element walls ranging in thickness from 2p same size as the bordered pits or large, elongate, and to 7p. The bulk of the radially oriented pores are fenestriform. intergrades between radial multiples and chains in The imperforate tracheary elements are nonseptate, which at least some pores have flattened tangential having walls which range in thickness from 2p to 6p walls. and from thin to very thick (lumens entirely oc- Vessel element length averages 575p, with a range cluded). The length of the fibrous elements averages of 300p to 750p and a MFR of 475p to 650p. Ves- 735p, with a range of 400p to 1175p and a MFR of sel element end walls are inclined at an average of 600p to 1OOOp. 44’. The vessel elements are generally ligulate. Vascular rays are predominantly uniseriate and Intervascular pitting comprises small bordered pits biseriate, with a few triseriate for at least a part of ranging in size from 4p to 6p in diameter. The pit their length. All ray types are heterocellular. Uniseri- apertures are oval to lenticular and are included ate raps are frequently short, ranging in height from within rounded to somewhat angular borders. 2 to 6 cells or more, and are composed of either Vessel to axial parenchyma pitting and vessel to square or upright cells, or both. A second type of ray parenchyma pitting is similar in size, shape, and uniseriate ray is generally higher, ranging up to 10 arrangement. The pit-pairs are half-bordered and cells or more in height, and consists of procumbent alternately arranged. The bordered pit of the vessel cells in addition to square and upright celIs, or both. element wall coincides in size and shape with those of The biseriate rays are generally higher than the the intervascular pit-pairs. Simple pits of the paren- 14 SMITHSONIAN CONTRIBUTIONS TO BOTANY chyma wall are round to oval and frequently elon- macerated material) . These small vessel elements gate, the latter fenestriform. intergrade with vascular tracheids. The imperforate tracheary elements are nonseptate. The larger of the two sizes are rounded and are having walls that vary in thickness from 2p to 5p either solitary or arranged in clusters. The large and range from thin in early wood to thick and very vessel elements are either ligulate or eligulate, with thick in late wood. These walls are optically inactive nearly horizontal end walls. and, as such, may indicate that the fibers are actually The average end all inclination of the combined gelatinous. The average length of the fibrous ele- vessel element types, as measured in tangential sec- ments is 1125p, with a range of 735p to 1428~and tion, is 76’. The average vessel element length is a MFR of 945p to 1300p. 200p, with a range of 130p to 290p and a MFR of Vascular rays are uniseriate to triseriate, with 160p to 250p. biseriate rays predominating. The uniseriate rays Intervascular pitting comprises small pits, rang- range from 1 to 7 or more cells high and most ing in size from 4p to 6p in diameter. Pit apertures frequently comprise only square and upright cells, are oval to lenticular. Pit borders are rounded. or both. Some procumbent cells are seen in the Vessel to axial parenchyma pitting and vessel to uniseriate rays. Bi- and triseriate rays are approxi- ray parenchyma pitting, when viewed in section, are mately the same size, ranging from 5 cells to over similar in appearance. The pit-pairs in both types 25 cells (600p) in height. In both the bi- and tri- of pitting are half-bordered. Pits in the vessel ele- seriate rays, the multiseriate portion of the ray com- ment wall are similar in size, shape, and arrange- prises procumbent cells, while the uniseriate “wings” ment to intervascular pits. A study of macerations or margins frequently comprise only square and up- reveals that the simple pits of the ray parenchyma right cells or both. The rays are heterocellular, com- are frequently small and slitlike to oval, while those prising all three cell types. Ray cells contain massive of the axial parenchyma are large, oval to elongate, amounts of starch and are frequently crystalliferous. and fenestriform. Axial parenchyma is present in apotracheal and Imperforate tracheary elements are frequently paratracheal arrangements. The apotracheal paren- septate, having walls from 2p to 4p thick, ranging chyma occurs as continuous bands, which are from very thin to thick. The average fibrous element usually, but not necessarily, marginal. When clearly length is 533p, with a range of 350p to 800p and a marginal, these bands are initial and are 1 to 2 cells MFR of 440p to 60011.. in width. The bands comprise strand parenchyma, A study of macerations indicates that two distinct many of which, having further subdivided, contain types of fibrous elements are present. One type is nonenlarged, optically active crystals. Diffusely ar- typically thick-walled, having attenuated ends and ranged crystalliferous strands are infrequently seen. infrequent, thin, solitary septa. The second type of The paratracheal parenchyma is exceedingly scanty, fibrous element is generally thin-walled, having not common to every vessel, and never completely truncate end walls. This second type is frequently vasicentric. All types of axial parenchyma contain septate. Septa are thick and range from 1 to 3 or massive amounts of starch. more per cell. Pitting is similar in both types and each may contain starch. Vascular rays are uniseriate to multiseriate, some SAPINDACEAE rays are 4 or more cells wide. The multiseriate rays Cardiospermum halicacabum L. : Faint growth rings frequently have uniseriate margins. The rays range are present. Pores are rounded to somewhat angular in height from a few cells to over 40 cells (800p). with walls varying in thickness from 4p to lop thick. The ray tissue is heterocellular, comprising upright, Two distinct sizes of vessel elements are present in square, and procumbent cell types. Upright and this species (Figure 35.) The smaller of the two square cells are most frequent, while procumbent sizes is generally angular and arranged in radial cells are relatively rare. The arrangement of cell multiples. These vessel elements are ligulate and types follows no discernible pattern. Two or more have end walls inclined at an average of 45’ (the cell types are commonly found in any given hori- measurement of the end wall angles are made on zontal row. Ray cells are often crystalliferous or NUMBER 5 15 contain starch. Some of the ray cells contain a dark- ray. The rays may be up to 20 cells (300p) or more staining, transparent to opaque substance of un- in height, but generally range from 4 to 10 cells known composition. high. Rays are heterocellular, comprising mainly Axial parenchyma is present in both apotracheal procumbent and square cells, with upright cells oc- and paratracheal arrangement. Diffuse parenchyma curring infrequently. There is no pattern of arrange- usually comprises crystalliferous strands. Additional ment of cell types, although the procumbent cell apotracheal parenchyma is present in the form of a type makes up the bulk of most rays, while the square discontinuous band that may have been traumatic cell type frequently occurs in marginal rows. Both in origin in my specimen. Cells in these apotracheal square and procumbent cells occur in the same hor- parenchyma bands are also frequently crystalliferous. izontal row. Most of the ray cells contain a dark- The crystalliferous idioblasts are nonenlarged rec- staining, transparent to opaque substance of unknown tangular cells, each containing a single optically composition. anisotropic prismatic crystal. They are arranged in Axial parenchyma is present in both apotracheal short vertical strands of from 3 to 10 or more cells. and paratracheal arrangements. Apotracheal paren- The paratracheal parenchyma is generally scanty chyma is mainly diffusely arranged, crystalliferous vasicentric, although a few cases of vasicentric are strand parenchyma. There is continuously banded seen. Axial parenchyma cells are frequently disjunc- apotracheal parenchyma 1 to 3 cells wide. The tive. Both types of axial parenchyma contain massive diffuse crystalliferous strands are of frequent amounts of starch and may contain the dark-staining occurrence, and range up to 30 cells or more substance seen in ray cells. in height. Strand cells, when viewed in longitudinal Cupania glabra Swartz: Growth rings are present section, are rectangular, with most of the cells in a but not distinct. The pores are rounded, having walls given strand being crystalliferous. Apotracheal bands from 2p to 7p thick. comprise primarily crystalliferous strand parenchyma, Average vessel element length is 414p, with a but unlike the diffuse strands, the cells of the bands range from 65p to 610p and a MFR from contain the same dark-staining substance seen in the 340p to 500p. Vessel element end walls are inclined ray cells. The paratracheal parenchyma is scanty at an average of 44'. The vessel elements are gen- vasicentric and frequently contains the same dark- erally ligulate. staining substance previously mentioned, Intervascular pitting comprises minute bordered Dodonaea viscosa (L.) Jacquin: Growth rings are pits which range from 2p to 4p in diameter. Pit absent. Pores are circular with walls varying in borders are rounded; pit apertures are rounded to thickness from 3p to 7p. elliptical and are included within the borders. Vessel element length averages 234p, with a range Vessel to axial parenchyma pitting is alternate to of 120p to 330p and a MFR of 200p to 270p. Vessel scattered. Many of the pits in the parenchyma cell element end walls are inclined at an average of 54'. walls are large, simple, and fenestriform with ir- Vessel elements are either ligulate or eligulate. regularly shaped margins. The pits in the vessel walls Intervascular pitting comprises minute bordered are slightly to completely bordered. Vessel to ray pits ranging from 2p to 4p in diameter. Pit borders parenchyma pitting is the same as that described for are rounded; pit apertures are lenticular and slightly vessel to axial parenchyma pitting. extended beyond or included within the borders. The imperforate tracheary elements are septate. Vessel to axial parenchyma pitting and vessel to Most of the fibrous elements contain 2 or more ray parenchyma pitting are very similar and both septa. The cell walls are 2p to 5p thick and are thin fit the following description. The arrangement of as compared with the diameter of the lumen. The pits in the vessel wall is alternate. Vessel to paren- average length of the fibrous elements is 697p, with chyma (both types) pit-pairs are half-bordered; the a range of 375p to 950p and a MFR of 630p to bordered pit of the vessel wall coincides in size and 840p. shape to the intervascular pits, while the simple pits Vascular rays are, for all intents and purposes, of the parenchyma wall are generally irregularly uniseriate. A few rays possess biseriate segments but shaped, ranging from circular to elongate, and are these are localized and never extend the length of a frequently fenestriform. 16 SMITHSONIAN CONTRIBUTIONS TO BOTANY

Imperforate tracheary elements are nonseptate, beyond the pit borders. having a wall thickness from 3p to 7p which ranges Vessel to ray parenchyma pitting and vessel to from thick to very thick, the lumens of some cells axial parenchyma pitting are very similar in appear- entirely occluded. The average length of the fibrous ance. In both cases, the arrangement of pits in the elements is 525p, with a range of 250p to 720,~and a vessel wall is alternate and the pits are similar in MFR of 440p to 650p. size and shape to intervascular pits. The vessel to Vascular rays are predominantly uniseriate. Some parenchyma pit-pairs (both types of parenchyma) biseriates are present, either as short biseriate seg- are half-bordered, with the simple pits of the paren- ments in otherwise uniseriate rays or as completely chyma wall ranging from circular to elongate, and biseriate rays. The rays are heterocellular, comprising fenestriform. procumbent and square cells. Very few upright cells The imperforate tracheary elements are septate, are seen. There is no discernible pattern of cell ar- most having two or more septa per cell. The cell rangement and both square and procumbent cell walls are 2p to 5, thick, and range from thin in types frequently occur in the same horizontal row. early wood to very thick in late wood. The average There is a tendency, however, for the main body of length of the fibrous elements is 716p, and the range a given ray to be composed primarily of procumbent is 440p to 1010p with a MFR of 630p to 800p. The cells. The occurrence of the square cells is sporadic fibrous elements often contain starch. in all cases, their arrangement random. Vascular rays are uniseriate and biseriate, the Uniseriate rays range in height from 2 to 20 cells latter type predominating. Uniseriate rays are gen- (300p) or more, while the biseriates generally range erally low, most are from 2 to 5 cells high. The bi- from 5 to 15 cells in height. The ray cells frequently seriate rays are somewhat higher, generally ranging contain a dark-staining, transparent to opaque sub- from 8 to 15 cells (250p). Upright cells are rare. Ar- stance of unknown composition. rangement of these cell types follows no pattern; Axial parenchyma is present in both apotracheal both procumbent and square cells occur in the same and paratracheal arrangement. Apotracheal paren- horizontal rows. Procumbent cells predominate and chyma is primarily diffuse, consisting mainly of comprise the bulk of most rays. Most ray cells con- crystalliferous strands. Some continuously banded tain a dark-staining, transparent to opaque sub- parenchyma occurs, these bands ranging in width stance of unknown composition in addition to starch. from 1 to 3 or more cells. The diffuse crystalliferous Axial parenchyma is present in both apotracheal strands are generally short, usually 10 or fewer cells and paratracheal arrangement. Apotracheal paren- per strand, and composed of slightly enlarged idio- chyma is present in diffuse crystalliferous strands and blasts, each containing a single optically anisotropic as banded and marginal parenchyma. The crystalli- prismatic crystal. The paratracheal parenchyma ferous strands are of frequent occurrence and range ranges from scanty vasicentric to aliform, with in- up to 20 cells or more in height. Crystalliferous idio- frequent confluent banding occurring. This banding blasts do not appear to be enlarged and each gen- is local (not continuous) and is definitely associated erally contains a single prismatic crystal. Bands of with the vessel elements. Axial parenchyma fre- parenchyma may be up to 5 cells wide and are com- quently contains the dark-staining material seen in posed of both crystalliferous and noncrystalliferous the ray cells. strands. The bands may or may not be marginal and Exothea paniculata (Jussieu) Radlkofer: Growth are unevenly spaced. The arrangement of the para- rings are present. Pores are rounded; the walls are tracheal parenchyma ranges from scanty vasicentric from 2p to 8p thick. to vasicentric. Vessel element length averages 428p, and ranges All types of axial parenchyma cells frequently con- from 245p to 560p, with a.MFR of 400p to 500p. tain starch and the dark-staining substance seen in Vessel element end walls are inclined at an average the ray cells. This dark-staining substance may also of 43 O, Vessel elements are generally ligulate. occur in the vessels. Intervascular pitting comprises minute bordered Hypelate trifoliata Swartz: Faint growth rings are pits, ranging from 2p to 3p in diameter. Pit borders present. Pores are rounded, with walls varying in are circular; pit apertures are lenticular and extend thickness from 3p to 7p. NUMBER 5 17

Vessel element length averages 319p, with a range is alternate and half-bordered in nature. The of 200p to 515p and a MFR of 275p to 400p. Vessel bordered to slightly bordered pits in the vessel walls element end walls are inclined at an average of 47'. are very similar in size and shape to intervascular The vessel elements are generally ligulate. pits, while the pits in the parenchyma walls are Intervascular pitting comprises minute pits rang- large and simple. ing from 2p to 4p in diameter. Pit apertures are Imperforate tracheary elements are septate, gen- rounded to oval and included within rounded to erally having a single thin septum in each cell. Walls polygonal borders. vary in thickness from 2p to 4p and are thin in com- Vessel to axial parenchyma pitting and vessel to parison with the dimensions of the lumens. The aver- ray parenchyma pitting are similar in appearance. age length of fibrous elements is 911p, with a range Both are alternate to scattered in arrangement and of 650p to 1180p and a MFR of 800p to 1100p. half-bordered, the pits in the vessel walls are similar Vascular rays are uni- to triseriate, with biseriate in size and shape to the intervascular pits. and triseriate rays predominating. Rays are homocel- The imperforate tracheary elements are non- lular, comprising only procumbent cells. The uni- septate, having walls which vary in thickness from seriate rays are generally short, from 2 to 10 or more 3p to 7p and range from thick to very thick, the cells high. A few of the uniseriate rays, when seen in lumens of some cells entirely occluded. The average tangential section, appear to be made up of some length of the fibrous elements is 632p, with a range enlarged square type cells. However, examination of of 420p to 850p and a MFR of 525p to 780p. radial sections showed that, although some cells were Vascular rays are uniseriate. The rays are hetero- higher than other cells, they were nevertheless radi- cellular, comprising procumbent, square, and up- ally elongate and thus procumbent. The biseriate right cells. The main body of most rays is composed and triseriate rays are generally higher than the uni- of square and procumbent cells, both frequently oc- seriates, ranging up to 50 cells (400p) or more in curring in the same horizontal row. Upright cells height. Infrequently, enlarged marginal cells are in are generally found in the marginal rows. The rays the bi- and triseriate rays, but examination of radial range in height from 2 to 25 cells (350p) or more, sections shows that these cells, although somewhat most rays are 10 or fewer cells high. larger, are still radially elongate. All of the rays fre- Axial parenchyma is present in both apotracheal quently contain large amounts of starch (starch and paratracheal arrangement. Apotracheal paren- grains). chyma is diffuse and comprises crystalliferous and Axial parenchyma is abundant and confluent. noncrystalliferous strands. The crystalliferous strands Whether this situation represents true confluent, that range from 4 to 30 cells or more per strand, com- is, paratracheal, parenchyma is difficult to determine, prising square idioblasts, each containing a single for the bands of axial parenchyma are frequently so prismatic crystal. Paratracheal parenchyma ranges wide as to occupy a large proportion of the ground- from vasicentric to aliform, with some confluent mass (Figure 18). These numerous, wide bands thus present. A few of the paratracheal parenchyma surround most of the vessels (pores). It would be strands contain crystalliferous cells. impossible, without ontogenic studies, to say whether Sapindus saponaria Linneaus : Growth rings are this is fortuitous. The bands comprise two types of absent. The pores are circular and have walls from strand parenchyma: strands of 2 to 4 axially elongate 2p to 5p thick. cells, and strands of many cells, a large number of Vessel element length averages 278p, with a range these crystalliferous. The largely crystalliferous strand of 120p to 390p and a MFR of 220p to 330p. End parenchyma is commonly found at the margins of walls are inclined at an average angle of 62'. In the parenchyma bands. These strands were not seen general, the vessel elements are ligulate. distributed among the fibrous elements. The crystal- Intervascular pitting consists of minute pits, rang- liferous idioblasts are not enlarged. Distinctly vasi- ing from 3p to 4p in diameter. The pit apertures are centric parenchyma is also seen in which cells are oval to lenticular and included within rounded to typically flattened and frequently disjunctive, form- somewhat angular borders. ing a complete sheath around each vessel or group of Vessel to both axial and ray parenchyma pitting vessels. These cells are distinct from the remainder 18 SMITHSONIAN CONTRIBUTIONS TO BOTANY

of the axial parenchyma because they contain the discontinuous and, as such, constitute an aliform con- same darkly stained substance found in the vessels. figuration with long “wings.” Axial parenchyma com- Starch grains often occur in cells of the banded prises strands generally consisting of four cells each. parenchyma, but not in cells of vasicentric paren- The strands tend to be storied. (Figure 23). Crystal- chyma. liferous strand parenchyma is also present, each strand consisting of 5 to 10 or more cells. The crystalliferous idioblasts are rectangular, nonenlarged SIMAROUBACEAE cells, each containing a single optically anisotropic Simarouba glauca DeCandolle : Growth rings are prismatic crystal. Axial parenchyma cells that are in absent. Pores are circular, with walls from 3p to 12p contact with vessel elements are generally flattened thick. and frequently disjunctive. Cells in strand paren- chyma frequently contain starch. Vessel element length averages 446p, with a range Suriana maritima Linnaeus: Growth rings are ab- of 270p to 560p and a MFR of 400p to 500p. Vessel sent. Pores are circular, with vessel element walls element end walls are inclined at an average of 60’. ranging in thickness from 2p to 6p. Vessel elements are generally eligulate. Vessel element length averages 173p, with a range Intervascular pitting comprises small bordered of 45p to 230p and a MFR of 165p to 200p. Vessel pits, ranging in size from 5p to 7p in diameter. Pit elements are generally eligulate. apertures are oval and included within rounded to Intervascular pitting comprises minute bordered somewhat angular borders. pits ranging in size from 3p to 4p in diameter. Pit Vessel to axial parenchyma pitting and vessel to apertures are lenticular to oval and are included ray parenchyma pitting is similar in size, shape, and within or are extended slightly beyond the rounded arrangement. The pit-pairs are half-bordered, the to somewhat angular borders. bordered pits of the vessel wall alternate and similar Vessel to axial parenchyma pitting and vessel to in size to the intervascular pits. The simple pits of ray parenchyma pitting are similar in size, shape, and the parenchyma are round to elongate, frequently arrangement. The pit-pairs are half-bordered and fenestriform. alternately arranged. The bordered pits of the vessel Imperforate tracheary elements are nonseptate, elements are similar to intervascular pits, while the having walls which range in thickness from 1p to 3p simple pits of the parenchyma (both ray and and vary from thin to very thin. The average length axial) are frequently large, oval to elongate, and of the fibrous elements is 794p, with a range of 550p fenestriform. to 111Op and a MFR of 650p to 950p. Imperforate tracheary elements are nonseptate, Vascular rays are uniseriate to multiseriate, with having walls which vary in thickness from 2p to 6p biseriate and triseriate rays predominating. Infre- and range from thin to thick. Some of the fibrous quently, the rays are up to five cells wide. All of the elements in Stern @ Briticky 230 are gelatinous and rays are similar in size, although the uniseriates are in Stern @ Brizicky 230 and Stern 2666 they contain generally shorter than the bi- and triseriates. The a darkly staining, translucent to opaque substance of uniseriate rays range from 4 to 10 cells or more high. unknown composition. The average length of the The bi- and triseriate rays range from 5 to 30 cells fibrous elements is 586p, with a range of 335p to (400p) or more high. Rays are heterocellular, al- 780p and a MFR of 460p to 700p. though composed almost entirely of procumbent Vascular rays are uni- and biseriate, with the cells: square cells are seen, but are infrequent in uniseriate rays predominating. Rays make up a large occurrence and random in arrangement. The rays portion of the groundmass as viewed in longitudinal cells frequently contain starch. Rays are storied section. Rays are heterocellular, comprising mainly (Figure 23). upright and square cell types, the procumbent cell Axial parenchyma is present in paratracheal ar- type occurs infrequently. Arrangement of the various rangement as narrow, anastomosing confluent bands. cell types is random. Both the uniseriate and the The bands are frequently continuous and range from biseriate rays are short, generally ranging from 3 to 3 to 10 cells or more wide. Some of the bands are 15 cells or more in height. All of the ray cells con- NUMBER 5 19 tain the dark-staining substance found in the fibrous than features of external morphology (Metcalfe and elements. Chalk 1950). As a result, differences in the wood Axial parenchyma is present in both apotracheal structure are inclined to be less dramatic than are and paratracheal arrangement. Apotracheal paren- differences in external morphology. Thus, Metcalfe chyma is diffuse and diffuse-in-aggregates and com- and Chalk state that ". . . this [the implastic nature prises noncrystalliferous strands consisting of two cells of wood structure], combined with its more conserva- or more per strand. The paratracheal parenchyma tive nature, adds to its value for the study of larger is scanty vasicentric to vasicentric, and frequently groups." comprises disjunctive cells. Both types of axial pa- In addition to being taxonomically valuable as a renchyma cells contain the same dark-staining sub- basis of classification, anatomical variations in sec- stance present in the fibrous elements and the ray ondary xylem may reflect the phylogenetic status of cells. An anastomosing arrangement of cells con- plant taxa. Although vessel element length may vary taining this substance is seen in transverse section greatly within different plants of the same species and comprises primarily the diffuse-in-aggregates and even within the tissues of the same plant, de- apotracheal parenchyma and rays. pending upon the age and position of the tissue Vessel elements frequently contain either this dark- studied (Bailey and Tupper 19 18), vessel element staining amorphous substance, or a granular sub- length is the most accurate reflection of the fusifom stance, which is similarly stained. Those vessel ele- cambial initial length (Chalk and Chattaway 1934). ments with empty lumens frequently have their cell Bailey and Tupper correlated fusiform cambial initial walls coated with this dark-staining substance. length, as reflected by the length of vascular ele- ments, with degree of evolutionary development Discussion based on both fossil and extant plants. They found that Calamitales, Lepidodendrales, and Cycadofili- Since structures which tend to be easily modified in cales, in addition to extant vascular cryptogams, response to environmental changes are of relatively possessed the longest tracheary elements ; gymno- little taxonomic importance, the choice of characters sperms, both extant and extinct, possessed tracheary to be studied is critical. In this respect, the compo- elements of intermediate length; and extant dicots nents of mature secondary xylem tissue are consid- had the shortest vascular elements. From this classic ered relatively implastic, especially when compared work, based on a large number of plants of wide with characters of external morphology (Metcalfe distribution within the extinct and extant tracheo- and Chalk 1950). Of the large number of anatomi- phytes, one is led to conclude that a reduction in cal characters discernible from study of mature sec- lengh of fusiform cambial initials is associated with ondary xylem, however, certain characters appear evolutionary advance (specialization) . to be more plastic than others. Characters incor- Frost ( 1930a, 1930b, 1931) , Bailey and Tupper porating dimensions are, in general, more apt to (1918), Kribs (1935, 1937), and others correlated vary with change in environment and growing con- the lengths of the fusiform cambial initials with other ditions. The presence or absence of growth rings, the features of dicotyledonous xylem anatomy. They con- lengths of fibrous elements, and the number of vessels cluded that definite trends of specialization accom- per unit area are examples of plastic characteristics panied the evolutionary reduction in length of the which are usually of little taxonomic significance. On fusiform cambial initials. the other hand, characters of form or arrangement Thus, the systematist, if he so chooses, has at hand are often less plastic and therefore more significant a tool of great potential taxonomic importance. Us- taxonomically. As examples of these, one may cite ing characters derived from the study of wood anat- the arrangement of intervascular pitting, the organi- omy as correlative and complementary information, zation of axial parenchyma, and the configuration he has an independent means of testing presumptive of perforation plates. phylogenetic relationships. These means are not In addition to the relatively implastic nature of based on the circuitous reasoning commonly en- the anatomical characters of wood, the structure of countered in classification based only on morpholog- wood tends to be evolutionarily more conservative ical characters, e.g., a plant is considered primitive SMITHSONIAN CONTRIBUTIONS TO BOTANY because it possesses a primitive flower type, which and Chalk 1950, Heimsch 1942) as having multiple itself is considered primitive because it is character- perforations in addition to simple perforations istic of a “primitive” taxon. The seemingly unrelated ( Campnosperma and Heeria) , Metopium is reported characters of perforation type, end wall inclination, as possessing only simple perforations (Heimsch intervascular pitting, etc., are now recognized as 1940). If the perforation observed is indeed a mul- constituting a syndrome or correlative complex use- tiple perforation and not a collection of fenestriform ful in reflecting not only form relationship, but the vessel to parenchyma pits clustered at the end of the evolutionary status of the plant. As Bailey (1957) vessel (as suggested in the description), the occur- stated, “The chief trends of evolutionary specializa- rence of such multiple perforations is extremely in- tion in the cambium and xylem of dicotyledons are frequent. Either interpretation leads one to conclude now so reliably established (except in the case of that, for all intents and purposes, the xylem of certain patterns of wood parenchyma distribution) Metopium is characterized by simple perforations. that they can be utilized to advantage in studying My observation that Toxicodendron radicans has salient problems of phylogeny and classification.” diffuse-porous wood raises some questions. The genus A final point must be made on the value of xylem Toxicodendron is reported (Heimsch 1942, Metca’fe anatomy in the overall scope of classification. In it- and Chalk 1950, Record and Hess 1943) as having self, xylem anatomy is of little inherent value to the generally ring-porous wood. Is the diffuse-porous taxonomists. Bailey (1953) stated that wood struc- wood of Stern 2633 (Figure 19) a result of environ- ture, as a collection of internal or endomorphic mental factors, or is it simply a feature of immature characters, is “. . . inherently no more conservative tissue? As noted in the description, the outer growth or reliable than are exomorphic ones.’’ Any given rings exhibit a tendency toward ring porosity. On the structure or character is not universally plastic or Florida Keys, T. radicans never has stems that even implastic; a character which may be implastic and approach the robust stems of this species growing in thus of taxonomic value within one group of plants, northeastern United States. It is possible that the de- may be quite variable and thus of little use in pauperate growth of the stem on the Keys may have another. Thus, endomorphic xylem characters of some bearing on the formation of ring porosity. The and by themselves, are of no more intrinsic value to climate of the Keys is probably conducive for p!ant the taxonomist than are exomorphic characters. growth throughout the year. This in itself will have However, when used in conjunction with other data an influence on the formation of growth rings and derived from external morphology, in addition to may seriously affect the expression of typical ring po- other areas of study, xylem anatomy can be of sig- rosity in this species as it occurs on these islands. nificant value. When utilized by itself, xylem anat- Spiral thickenings are not present in the vessel ele- omy best serves the taxonomist as a means of nega- ments of T. radicans, although all memberss of the tion of relatedness among taxa (Bailey 1957, Cron- genus Toxicodendron are reported (Record 1939) quist 1968). Because of the ever-present possibility as having this feature. Heimsch (1940) reports the that similar structures may result through parallel presence of spiral thickenings in the small vessel evolution, xylem characters alone cannot be con- elements of only T. uernix and the Asiatic T. tricho- sidered as indicative of positive relationship without carpum. Heimsch notes, as a possible explanation the strong support of supplemental data. of this discrepancy, that the portions of the vessel A brief comparison of the anatomical features of element wall occurring between the slitlike inter- the taxa included in this study follows. In general, vascular pits and the fenestriform vessel to paren- these anatomical features conform well with those chyma pits give the impression of spiral thickenings previously reported in the literature. Some discrep- in unstained or poorly stained sections. My observa- ancies are indicated below. tions agree with those of Heimsch to the extent that The single observation of an apparent multiple no spiral thickenings were seen in the specimen of perforation plate in Metopium toxiferum is unique T. radicans. in that all other perforations observed in this study * Record’s description of the wood characters of the are simple. Although at least two genera of Ana- genus Toxicodendron is based on specimens of T. diversiloba, cardiaceae are reported in the literature (Metcalfe T. radicans, and T. vernix. NUMBER 5 21

Striking similarities occur among Metopium toxi- the rutaceous taxa of at least some radial chain pore ferum, Toxicodendron radicans, and Bursera sima- arrangement (Figure 15). In other Pinnatae, the ruba. These s;ecies have fenestriform vessel to pa- radially oriented pore groups comprised only radial renchyma pit-pairs (Figure 32). Metopium toxiferum multiples (Figure 12). All members of the Rutaceae and Bursera simaruba have medium-sized (in diam- have banded and diffuse axial parenchyma in addi- eter) intervascular pitting. Other species of Pinnatae tion to some paratracheal parenchyma. Swietenia studied have vessel to parenchyma pitting which is mahagoni, Metopium toxiferum, and several mem- very similar structurally to the intervascular pitting, bers of the Sapindaceae also have this combination of the intervascular pits ranging in size from small axial parenchyma arrangements. Amyris and Citrus to minute in diameter. Metopium toxiferum and have enlarged crystalliferous idioblasts (Figure 25), Bursera simaruba have horizontal intercellular canals as does Dodonaea of the Sapindaceae. The occur- in their rays (Figure 24). Record (1939) notes that rence of crystals in either ray parenchyma or axial these canals occur in Toxicodendron diversiloba, parenchyma is a nearly universal character of the although Heimsch (1940) did not observe radial species studied. Only Metopium toxiferum, Toxico- canals in any members of the genus. Rays in Meto- dendron radicans, and Suriana maritima lack such pium toxiferum, Bursera simaruba, Swietenia ma- crystals. hagoni, and the two species of Zanthoxylum are so Although the xylem anatomy of Cardiospermum similar as to be hardly distinguishable, except for halicacabum is not described in the literature the occurrence of intercellular canals. (Heimsch 1942, Metcalfe and Chalk 1950, Record Field collection of the two species of Zanthoxylum and Hess 1943), the xylem of two genera (Serjania points up an obvious difference between Z. fagara and Paullinia) of sapindaceous lianas are described. and Z. flavum. Although Z. flavum is reported in the The occurrence of two distinct vessel element types literature as possessing wood (heartwood) which is in Cardiospermum (Figure 35) noted above con- ". . . exceedingly hard and heavy" (Small 1933), forms with the descriptions of vessel elements given having ". . . sp. gr. .90, 56 Ibs./cu. ft." (Record and for Serjania and Paullinia (Heimsch 1942, Metcalfe Hess 1943), hand sawing showed that, of the two and Chalk 1950). The presence of dimorphic vessel species, Z. fagara was much harder. Upon study of elements is likely related to the lianous habit in this the sections of Z. flavum, I was surprised to note family. the presence of thick-walled fibers and a small Throughout this investigation, various anatomical amount of axial parenchyma (as compared with characteristics were evaluated, with the hope that1 Z. fagara, Figures 14, 15), certainly not what one a significant set of these could be found which might would expect of the very soft wood Z. flavum proved reflect the present familial arrangement of the 16 to be on sawing. Observation of transverse sections species studied. Although certain families did possess under crossed nicols reveals, however, that the sec- anatomical features which served to identify their ondary wall thickenings of the fibrous elements members, other families did not possess such unify- of Z. flavum are optically inactive, while those of ing features. However, all the members of Pinnatae Z. fagara are optically active. This indicated that, do exhibit many anatomical characters in common although the secondary walls of the fibrous elements to indicate that we are dealing with a remarkably of Z. flavum are lignified (take up safranin stain homogeneous group of plants. readily), the orientation of the cellulose micelles of Comparison among families of Pinnatae of those these secondary walls is such that polarized light anatomical characters considered to be of greatest is not refracted in the transverse plane of section. taxonomic and phylogenetic significance by Metcalfe Although not typical in appearance, one could refer and Chalk (1950) reveals that (1) all members to these fibrous elements as gelatinous, owing to the possess vessel elements having simple perforations, apparent noncrystalline nature of the secondary wall (2) the vessel elements of all members have alter- thickenings. The wide occurrence of gelatinous fibers nately arranged intervascular pitting, (3) all mem- could explain the softness of the wood in Z. flavum. bers possess fibers with slitlike simple to slightly A character which separates members of the Ru- bordered pits, and (4) all members possess at least taceae from the other Pinnatae is the presence in paratracheal axial parenchyma, with the banded 22 SMITHSONIAN CONTRIBUTIONS TO BOTANY configuration (paratracheal and apotracheal) the rays of each species are similar. The rays of species most common. Although anatomical differences exist having only uniseriates are low, rarely exceeding among the 16 species studied, none of these is great 2OOp in height. Those rays in species having multi- enough to warrant the exclusion of any one of the seriates are also low, rarely exceeding 600p in height. members from this group. By and large, greater The widest multiseriate rays do not exceed 10 cells anatomical differences are seen to exist among gen- (loop) in width. era within the same family (e.g., Sapindaceae- Looking at anatomical characters which vary Table 4) and even among species of the same genus within the group as a whole, but remain relatively (e.g., Zanthoxylum-Table 4), than exist among constant at the family level, we find an interesting the families represented in this group. and significant segregation. The nature of the vessel Although the ray structure encountered in this to parenchyma (both axial and ray) pitting is re- study varies in regard to cellular makeup (hetero- markably consistent among the 15 genera, with the cellular as opposed to homocellular, uniseriate as three exceptions of Bursera, Metopium, and Toxico- opposed to multiseriate) , the relative sizes of the dendron. Only Bursera and Metopium of the 15

TABLE4.-Summary of xylem anatomical data in the "Pinnatae" - - -ELEK -S ci 42 i 4 J ria u u n" ri ria SPECILS OJrimac 5 y11 maLoo 42 > .5 >d L, GI- :% ?$ 3.4 ;2 r ma Nu i -4: -2: -0)-.i ANACAFDIACEAE

Metapiir. toxife?wi 375 4ir medim B, Al, C Toxicade?.dron radicans 253 41 Small D, s, v

BURSEFACEAE __-B~rserasisaruba 531 48 rnediwr. S 1,2,1,~ het TZLIACFAE

Swietenia mhegoni '137 62 nin-te B, #, S, 'J

RUTACEAE Amyris elernifera 25c 55 sinute 1, horn.

Citm6 aurantiifolia 273 58 srnE.11 L,3,ZnL,het Zanthaxyllun 261 64 minute L33,het. _-2. fl8"Ul 515 44 small 1,33,het. SApINDACEbi

Cardiospemm halicesabm 200 76 small

Cupacia glabra 414 44 minute ~__Jkdanaea viscose 234 54 minure panim1ata 426 43 minute melate trifoliata 319 '17 minute Sepindus sapoIia?ia 278 62 m.ir.use SDNLROUBACEAE Simmuba glauca 446 6c small C, A1 --Suriana maritima -173 -63 minute D, s, v

'Classification of intervascular pitting follows that swgested by Record snd Chattaway (19?9).

bUnderlined nurr.bers indicate the predominant ray type (2 = tPiEeriste rays most freqilent ).

*Xembers having Septate fibrous elements which contain starch. NUMBER 5 23 genera possess intervascular pits of medium size, the Cardiospermum have septate fibrous elements that other 13 genera have either small or minute pits. contain this storage product (Figures 12,13,24,29) . Four genera possess heterocellular multiseriate rays This feature may be of some taxonomic import in having uniseriate wings, and among them are Bur- that it is correlated with a relatively small amount sera and Metopium. Add to this the horizontal inter- of axial parenchyma in these taxa. This observation cellular canals in the rays of both Bursera and Meto- is in agreement with those of Harrar ( 1946). pium, and one recognizes that the members of the The occurrence of septate fibrous elements appears Florida Keys Pinnatae may be subdivided on the to be a local phenomenon and is of little taxonomic basis of xylem anatomy so that the genera of Ana- significance in this group (the Pinnatae) . The only cardiaceae and Burseraceae are by and large dis- families that have members lacking septate fibers, tinguishable from the other genera. based on the species in this study, are Rutaceae and Phylogenetic interpretation of the data derived Simaroubaceae. Both of these families, however, have from this study indicates that the woods of the 16 other members that have septate fibers (Metcalfe species exhibit a high degree of specialization. The and Chalk 1950). syndrome of short to medium length vessel elements, The taxonomic value of diffuse-porosity is also simple perforation plates, alternate intervascular pit- questionable, The effect of environment on the ting, and absence of steeply inclined vessel element topography of wood is not certain. The great ma- end walls shows that the members of the Pinnatae jority of tropical trees having distinct growth rings studied are at approximately the same relatively possess woods that are diffuse-porous, and the OC- advanced level of specialization. In addition, the currence of ring-porosity is largely restricted to woody storied structure, found in Simarouba and Swietenin plants of the North Temporate Zone (Gilbert 1940). (Figure 23), represents another line of specialization The fact that all members, with the possible excep-, which occurs only in certain Pinnatae. Kribs (1935) tion of Toxicodendron, have diffuse-porous wood is considered woods having either homocellular rays thus of debatable taxonomic value here. (Amyris and Sapindus) or strictly uniseriate rays A survey of the literature (Metcalfe and Chalk (Amyris, Cupania, and Hypelate) as highly ad- 1950), concerning both morphological and anatomi- vanced. The rays of Suriana are, for all intents and cal characteristics of the families concerned with in purposes, uniseriate. Heterocellular rays which are this study, shows that the occurrence of secretory made up in large part of procumbent cells, with structures (Figures 24-27) characterizes members the square and upright cells, or both, occurring only of the Pinnatae. The intercellular canals of anacar- sporadically and infrequently (Citrus and Sima- diaceous and burseraceous woods, and the inter- rouba) , are also considered as relatively advanced. cellular canals in the bark and pith of these families, The common ray configuration (procumbent cells as well as Simaroubaceae and Sapindaceae, are comprising the multiseriate portion with upright' examples of such structures. Secretory cells are re- and square uniseriate wings or both) seen in Meto- ported as occurring in the pith and cortex of all pium, Bursera, Swietenia, and Zanthoxylum, in ad- families. The occurrence of pellucid glands in the dition to the low rays found in the remainder of leaves of Rutaceae is well known. In addition, trau- the genera, constitutes an advanced ray situation. matic axial canals are reported to occur either fre- The presence of various aggregate arrangements of quently or sporadically in some members of all fam- axial parenchyma, such as banded, aliform and ilies, with the exception of Sapindaceae and Ana- confluent, or both (only Toxicodendron, Bursera, cardiaceae. The widespread presence of dark-stain- and Suriana lack such arrangements), is accepted ing, gumlike substances in the parenchyma and as being advanced. The occurrence of fibrous ele- vessels of many of the species seen in -this study ments lacking distinctly bordered pits is also an (Figures 20,22) suggests the secretory potential of advanced characteristic. these members. The traumatic axial canal observed The wide occurrence of starch grains in the par- in Zanthoxylum fagara also contained a darkly stain- enchymatous tissue of the specimens studied prob- ing deposit. Crystals, which occur widely in the ably is of little taxonomic significance. However, xylem of Pinnatae are products of idioblasts. These specimens of Toxicodendron, Bursera, Exothea, and too are considered as secretory cells. Thus, the oc- SMITHSONIAN CONTRIBUTIONS TO BOTANY currence of secretory structures in most, if not all The only separation of families within Pinnatae members, may be of taxonomic value; insofar as it suggested by a syndrome of several unique charac- might serve as another indication of the homogeneous teristics is the formation of an Anacardiaceae-Bur- nature of Pinnatae. seraceae complex. These characteristics, however, The data derived from this study indicate that when viewed in light of the many common features the Pinnatae constitute a homogeneous group, and of the families, are not sufficient bases for the sepa- that no anatomical basis exists for segregation of the ration of the Anacardiaceae and Burseraceae from various members into separate orders. The traditional the Pinnatae as a group. Englerian separation of the Sapindaceae and Ana- There is no anatomical basis for the separation cardiaceae from the remainder of the families is not of families into distinct orders as proposed by Engler, supported by xylem anatomy. Hutchinson’s separa- Hutchinson, Takhtajan, and others. The system of tion of the families into three orders, and Takhta- classification proposed by Cronquist is anatomically jan’s and Thorne’s separation of Sapindaceae from feasible except for his exclusion of Suriana from the the other families, likewise, have no anatomical basis. Simaroubaceae. The members of the Pinnatae are Cronquist’s treatment most nearly reflects the ana- seen by this author as belonging to a taxon corre- tomical similarities that exist, with the exception sponding well with Cronquist’s Sapindales. that he removes Suriana from the Simaroubaceae Phylogenetically, the Pinnatae constitutes an ad- and places it into the Stylobasiaceae. There is no vanced taxon. Simple perforation plates, short to anatomical foundation for the separation of Suriana medium length vessel elements having alternate in- from the Simaroubaceae. This conclusion is based tervascular pitting, slightly inclined vessel element both on data derived from this study and the ana- end walls, advanced ray types, fibrous elements with tomical literature (Webber 1936). Cronquist’s (1968) simple or vestigially bordered pits, and the predomi- assignment of Suriana and Stylobasium to his Stylo- nant banded and confluent axial parenchyma mark basiaceae is based on characters of habit and mor- the Pinnatae anatomically as a highly specialized phology, and a complete study of the anatomy of group. The possession of storied rays in two species Stylobasium and Suriana must be carried out before is another trend of specialization. such an association can be anatomically evaluated. Based on the data derived from this anatomical The inclusion of Anacardiaceae and Burseraceae in study and from the literature, the 16 species of the single family Terebinthaceae, as proposed by Florida Keys Pinnatae are members of a homogene- Hallier (1912), is supported by xylem anatomy. ous, phyletically advanced group. Furthermore, that this group constitutes a genetically related complex of plants is borne out by correlative studies in floral Summary and vegetative morphology, as well as by the sub- A study of the wood of 16 species of Florida Keys stantial anatomical studies of which this investiga- Pinnatae indicates that the group is anatomically tion is a part. These members belong in the Sapin- homogeneous. All members possess simple perfora- dales as described by Cronquist. tion plates, vessel elements having alternate inter- vascular pitting, fibrous elements with small slitlike, simple to vestigially bordered pits, and axial pa- Literature Cited renchyma which is both apo- and paratracheal. Ayensu, E. S. Crystals are of wide occurrence in the parenchyma 1967. Aerosol OT Solution-An Effective Softener of cells, and banded and aliform to confluent paren- Herbarium Specimens for Anatomical Study. Stain chyma occur in several taxa. Certain families or Technology 42: 155-156. groups of families have unique characters : radial Bailey, I. W. chain arrangement of pores in the Rutaceae, random 1953. The Anatomical Approach to the Study of Genera. arrangement of cells in the heterocellular ray types Chronica Botanica 14: 121-125. among members of the Sapindaceae, and fenestriform 1957. The Potentialities and Limitations of Wood Anat- omy in the Study of the Phylogeny and Classifica- vessel to parenchyma pit-pairs and intercellular ca- tion of Angiosperms. Journal of the Arnold Arbo- nals in the rays of Anacardiaceae and Burseraceae. retum 38: 243-254. NUMBER 5 25

Bailey, I. W., and W. W. Tupper Area: I. Anacardiaceae. Australian Journal of 1918. Size Variation in Tracheary Cells: I. A Com- Scientific Research, Series B., Biological Sciences parison Between the Secondary Xylems of Vascular l(4) :391-415. Cryptogams, Gymnosperms and Angiosperms. Pro- Engler, A,, and L. Diels ceedings of the American Academy of Arts and 1936. Syllabus der Pflanrenfamilien. 11th ed. Berlin, Sciences 54 : 149-204. Germany: Geb. Borntraeger. Barkley, F. A. Frost, F. H. 1937. A Monographic Study of Rhus and Its Immediate 1930a. Specialization in Secondary Xylem of Dicotyle- Allies in North and Central America, Including dons: I. Origin of vessels. Botanical Gazette 89: the West Indies. Annuals of the Missouri Botanical 67-94. Garden 21: 265-498. 1930b. Specialization in Secondary Xylem of Dicotyle- Bentham, G., and J. D. Hooker dons: 11. The Evolution of the End Wall of the 1862-1 883. Genera Plantarum. 3 vols. London, England: Vessel Segment. Botanical Gazette 90: 198-212. L. Reeve and Co. 1931. Specialization in Secondary Xylem of Dicotyle- Brizicky, G. K. dons: 111. Specialization of the Lateral Wall of 1962a. The Genera of Rutaceae in the Southeastern the Vessel Segment. Botanical Gazette 91 : 88-96. United States. Journal of the Arnold Arboretum Gilbert, S. G. 43: 1-22. 1940. Evolutionary Significance of Ring Porosity in 1962b. The Genera of Simaroubaceae and Burseraceae in Woody Angiosperms. Botanical Gazette 102 : 105- the Southeastern United States. Journal of the 120. Arnold Arboretum 43 : 173-186. Gutzwiller, M. A. 1962c. The Genera of Anacardiaceae in the Southeastern 1961. Die phylogenetische Stellung von Suriana mari- United States. Journal of the Arnold Arboretum tima L. Botanische Jahrbucher fur Systematik, 43:359-375. Pflanrengeschichte und Pflanzengeographie 81 : 1- 1963. The Genera of Sapindales in the Southeastern 49. United States. Journal of the Arnold Arboretum Hallier, H. 44:462-501. 1905. Provisional Scheme of the Natural (Phylogenetic) Candolle, A. P. de, and A. de Candolle System of Flowering Plants. New Phytologist 4: 1824-1873. Prodromus systemates naturalis regni vege- 151-162. tabilis. 17 vols. and 4 index vols. Paris, France: 1912. L’origine et le systeme phyletique des Angio- Treuttel and Wurtz. spermes. Archives Neerlandaises des Sciences Ex- Chalk, L. actes et Naturelles, Series IIIB, 1 : 146-234. 1944. The Taxonomic Value of Wood Anatomy. Pro- Harrar, E. S. ceedings of the Linnean Society of London 155: 1946. Note on Starch Grains in Septate Fibers. Tropical 2 14-218. Woods 85 : 1-9. Chalk, L., and M. M. Chattaway Heimsch, C., Jr. 1934. Measuring the Length of Vessel Members. Trop- 1940. Wood Anatomy and Pollen Morphology of Rhus ical Woods 40: 19-26. and Allied Genera. Journal of the Arnold Arbo- 1935. Factors Affecting Dimensional Variations of Ves- retum 21 :279-297. sel Members. Tropical Woods 41 : 17-37. 1942. Comparative Anatomy of the Secondary Xylem Committee on Nomenclature, International Association of of the “Gruinales” and “Terebinthales” of Wett- Wood Anatomists stein with Reference to Taxonomic Grouping. 1957. International Glossary of Terms IJned in Wood Lilloa 8:82-198. Anatomy. Tropical Woods 107: 1-36. Hess, R. W. Cronquist, A. 1946. Identification of New World Timbers: Part 11. The Evolution and Classification of Flowering 1968. Anacardiaceae. Tropical Woods 87 : 11-34. Plants. Boston, Massachusetts: Houghton Mifflin Hutchinson, J. co. The Phylogeny of Flowering Plants. Proceedings of Dadswell, H. E., and A. M. Eckersley 1926. the International Congress of Plant Science, 1938. The Wood Structure of Some Australian Rutaceae Ithaca with Methods for Their Identification. The Coun- 1:413-421. The families of flowering plants. 2nd ed. vol. cil for Scientific and Industrial Research, Aus- 1959. 1. pp. 353-363. Oxford : Clarendon Press. tralia, 114:1-32. Dadswell, H. E., and D. J. Ellis Jadin, F. 1939. The Wood Anatomy of Some Australian Meliaceae 1901. Contribution a l’etude des Simarubacees. Annale.r with Methods for Their Identification. The Coun- des Sciences naturalles; botanique. Paris, Serie 8. cil for Scientific and Industrial Research, Aus- 13:201-304. tralia, 124: 1-20. Johansen, D. A. Dadswell, H. E., and H. D. Ingle 1940. Plant microtechnique. New York: McGraw-Hill 1948. The Anatomy of Timbers of the Southwest Pacific Book Co. SMITHSONIAN CONTRIBUTIONS TO BOTANY

Keck, D. D. 19 1 1. Simaroubaceae. North American Flora 25 : 227- 1937. Trends in Systematic Botany. Suraey of Biological 239. Progress, 3 : 47-97. New York: Academic Press. 1913. Flora of the Florida Keys. New York: Published Kribs, D. A. by the Author. 1930. Comparative Anatomy of the Woods of the Mel- 1933. Manual of the Southeastern Flora. New York: iaceae. American Journal of Botany 17: 724-738. Published by the Author. 1935. Salient Lines of Structural Specialization in the Stern, W. L. Wood Rays of Dicotyledons. Botanical Gazette 96 : 1952. The Comparative Anatomy of the Xylem and the 547-55 7. Phylogeny of the Julianiaceae. American Journal 1937. Salient Lines of Structural Specialization in the of Botany 39: 220-229. Wood Parenchyma of Dicotyledons. Bulletin of the Stern, W. L., and K. L. Chambers Torrey Botanical Club 64: 177-187. 1960. The Citstion of Wood Specimens and Herbarium Linnaeus, C. Vouchers in Anatomical Research. Taxon 9:7-13. 1753. Species plantarum. 2 vols. Stockholm, Sweden: Takhtajan, A. Laurentii Salvii. 1966. Systema et phylogenia magnoliophytorum. Melchior, H. “Nauka,” Moscow and Leningrad (In Russian). 1964. Engler’s Syllabus der PfEanzenfamilien. 12th ed. Thorne, R. F. Pages 246-284. Berlin, Germany: Geb. Borntraeger. 1968. Synopsis of a Putatively Phylogenetic Classifica- Metcalfe, C. R., and L. Chalk. tion of the Flowering Plants. Aliso 6:57-66. 1930. Anatomy of the dicotyledons. 2 vols. Oxford, Tippo, 0. England : Clarendon Press. 1941. A List of Diagnostic Characteristics for the De- Record, S. J. scription of Dicotyledonous Woods. Transactions 1939. American Woods of the Family Anacardiaceae. of the Illinois State Academy of Science 34: 105- Tropical Woods 60: 11-45. 106. 1941. American Timbers of the Mahogany Family. Trop- 1946. The Role of Wood Anatomy in Phylogeny. Ameri- ical Woods 66: 7-33. can Midland Naturalist 36: 362-372. Record, S. J., and M. M. Chattaway Webber, I. E. 1939. List of Anatomical Features Used in Classifying 1936. Systematic Anatomy of the Woods of the Simaru- Dicotyledonous Woods. Tropical Woods 57 : 11-16. baceae. American Journal of Botany 23 :577-587. Record, S. J., and R. W. Hess 1941. Systematic Anatomy of the Woods of the Bur- 1943. Timbers of the New World. New Haven, Connec- seraceae. Lilloa 6: 441-465. ticut : Yale University Press. Wettstein, R. Sass, J. E. 1935. Handbuch der systematischen Botanik. 4th ed. 1958. Botanical microtechnique. 3rd ed. Ames, Iowa: Leipzig and Wien: Deuticke. Iowa State University Press. Wilson, P. Small, J. K. 191 1. Surianaceae. North American Flora 25 :225. NUMBER 5 27

FIGURE1-4-1, Toxicodendron radicans: habit showing flowers; 2, Bursera simaruba: habit indicating size of tree; 3, Bursera simaruba: leaves and fruit; 4, Swietenia nahagoni: habit in- dicating size of tree. 28 SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURES5-8.-5, Zanthoxylum flavum: leaf showing glandular dots; 6, Sapindus saponaria: habit with fruits and leaves (note winged rachis of pinnately compound leaves) ; 7, Sapindus saponaria: fruits; 8, Cardiospermum halicacabum: habit with fruits and flowers. NUMBER 5 29

FIGURES9-1 1.-9, Cupania glabra: fruits and leaves; 10, Simarouba glauca: flowers; 11, Suriana maritima: flowers (note simple leaves). 30 SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURES12-15.-12, Bursera simaruba: transverse section showing radial multiples and solitary pores (note starch in the fibers), X 246; 13, Bursera simaruba: transverse section viewed under crossed nicols (polarized light) showing the birefringent property of the cell walls and starch grains, X 269; 14, Zanthoxylum fagara: transverse section showing banded parenchyma and radially oriented pore multiples and chains, X 269; 15, Zanthoxylum fiavum; transverse section showing large amounts of thick-walled fibers. Banded parenchyma and radially oriented pore multiples and chains are also shown (note the presence of starch grains in both ray and axial parenchyma), X 269. NUMBER 5 31

FIGURES16-19.-16, Cupania glabra: transverse section showing growth rings, and solitary, radial multiples, and clusters of pores, X 109; 17, Simarouba glauca: transverse section show- ing aliform and confluent parenchyma arrangement, X 97 ; 18, Sapindus saponaria: transverse section showing confluent bands of parenchyma, X 97 ; 19, Toxicodendron radicans: transverse. section showing qdestionable diffuse-porous distribution of pores, X 246. 32 SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURES20-23.-20, Cupania glabra: radial section showing randomly arranged procumbent, square and upright cells. Note the gumlike substance in ray cells, X 390; 21, Metopium toxiferum: Tangential section showing rays having uniseriate “wings,” X 246; 22, Swieteniu mahagoni: Radial section showing rays having square and upright, or both, marginal cells, X 97; 23, Simarouba glauca: tangential section showing the storied arrangement of rays and axial strand parenchyma, X 97. NUMBER 5 33

FIGURES24-27.-24, Bursera simaruba: tangential section showing intercellular canals in the rays (note the starch grains in the septate fibers), X 269; 25, Citrus aurantiijolia: radial sec- tion showing enlarged crystalliferous idioblasts, X 539 ; 26, Zanthoxylum fagara: Transverse section showing traumatic intercellular canal, X 269 ; 27, Zanthoxylum fagara: radial sec- tion showing the traumatic intercellular canal in longitudinal section, X 539. 34 SMITHSONIAN CONTRIBUTIONS TO BOTANY

FIGURES28-32.-28, Exothea paniculata: radial section showing slitlike simple to slightly bordered fiber pits in face view (arrow), X 1872; 29, Exothea paniculata: tangential section showing the fiber pits in transverse section (arrow). Note starch grains, X 1872; 30, Citrus aurantiifolia: tangential section showing alternate intervascular pitting. Note the coalescence of adjacent pit apertures (arrow), X 734; 31, Metopium toxiferum: tangential section show- ing unilaterally compound intervascular pittings (arrow), X 1872 ; 32, Bursera simaruba: maceration showing the occurrence of fenestriform vessel pitting. These pits occur in the cell walls of both vessel elements and parenchyma. Note the simple perforation plate, X 269. NUMBER 5 35

FIGURES33-35.-33, Amyris elmifera: radial section showing tyloses and granular, translucent material in the vessel elements, X 292; 34, Metopium toxijerum: transverse section showing tyloses in vessels and the occurrence of gelatinous fibers, X 269; 35, Cardiospermum hali- cacabum: transverse section showing large solitary pores and radial multiples of small angular pores (arrow), X 269.

* U.S. OOVERNMCNT PRlNTlNQ OFFICE: 1972-417--398/12