IAWA Bulletin n.s., Vol. 6 (1), 1985 3

WOOD ANATOMY OF THE STYRACACEAE: EVOLUTIONARY AND ECOLOGICAL CONSIDERATIONS

by

William C. Dickison and Kristen D. Phend Department of Biology, The University of North Carolina, Chapel Hill, North Carolina 27514, U.S.A.

Summary Woods of over 40 species representing nine Key words: Styracaceae, Lissocarpaceae, sys­ genera of Styracaceae were studied. Features tematic anatomy, ecological wood anatomy, present in most taxa include growth rings, dif­ latitude. fuse porosity, combinations of both solitaries and pore multiples, exclusively scalariform per­ Introduction foration plates, opposite to alternate intervessel The Styracaceae are a woody, dicotyledonous pitting, imperforate tracheary elements with in­ family that is generally described as containing distinctly bordered pits, both uniseriate and 12 or 13 genera and 150 to 190 species (Wood, multiseriate heterocellular rays, and axial pa­ 1960; Hutchinson, 1973; Gonsoulin, 1974; renchyma distributed as a combination of dif­ Spongberg, 1976). The plants are distributed fuse, diffuse-in-aggregates, and scanty. Prismatic primarily in eastern Asia to western Malaysia, crystals occur in species of the genera Bruins­ tropical South America, and the southeastern mia, Halesia, and Styrax, and silica is present in United States. a few Neotropical species of Styrax. The char­ The largest genus, Styrax, includes about 120 acteristic solitary pore distribution and high species and ranges widely in the tropical and scalariform perforation plate bar number of warm temperate regions of eastern Asia and Huodendron are of potential evolutionary sig­ America. A conspicuous exception to this dis­ nificance. The xylem of Lissocarpa differs from tribution pattern is Styrax officinalis L., which the Styracaceae in possessing more highly is found in the eastern Mediterranean region evolved vessel elements with both simple and and in California. In Asia the numerous species scalariform perforations and prominently band­ extend from the eastern Himalayas to Malaysia, ed axial parenchyma. The occurrence of simple Indochina, Korea, and Japan. The family is ab­ perforation plates in the wider, earlywood ves­ sent from Australia, the Philippines, and Sri sel elements, along with an increased pore fre­ Lanka. The New World species are widely dis­ quency and decreased vessel element length, in tributed from Pacific to Atlantic North Ameri­ Styrax platanifolius and S. texan us is document­ ca, the West Indies, and southward to southern ed. Both species inhabit seasonally dry habitats Brazil. of the southwestern United States, thus sup­ As reviewed by Schadel and Dickison (1979), porting similar specialisations observed in other the Styracaceae have been generally placed in plants growing in xerophytic conditions. The the order Ebenales including, in addition, the apparent variation in perforation plate condi­ families Sapotaceae, Ebenaceae, Symplocaceae, tion within different geographic varieties of S. and Lissocarpaceae (Cronquist, 1981; Thorne, officinalis is discussed. Significant correlations 1976; Takhtajan, 1980). of wood anatomical characters and latitude of No comparative evolutionary survey of styra­ provenance are present among species of Styra­ caceous wood anatomy has been completed, al­ caceae. Increasing latitude is strongly corre­ though there are several descriptive works, of­ lated with increased pore and multiseriate ray ten regional in nature, dealing with the xylem frequency, and decreased vessel element length structure of various species. The most notable of and wall thickness. Increasing latitude is less these are: Chudnoff (1956), Kanehira (1921), strongly correlated with an occurrence of de­ Inokuma et al. (1953), Metcalfe & Chalk (1950), creased pore diameter, increased bar number Sudo (1959), Versteegh (1 968), Moll & Jansso­ per perforation plate, increased fibre-tracheid nius (1906), Record & Hess (1943), Tang (1932- and intervessel pit diameter, and increased fre­ 1934), and Tortorelli (1956). quency of uniseriate rays. Weak correlations Nevertheless, the wood of this family has are also evident between increasing latitude and neither been fully described nor adequately shorter ray height and narrower, shorter, and interpreted ecologically and evolutionarily. A thinner-walled fibre-tracheids. study of the comparative anatomy of the Styra-

Downloaded from Brill.com10/07/2021 04:17:38AM via free access .j>. Table I. Secondary xylem characteristics of Styracaceae (s. s.)

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* Immature sample. via freeaccess ** All specimens studied were from Israel. California plants of this species have both simple and scalariform perforation plates. VI 6 IAWA Bulletin n.s., Vol. 6 (1),1985

caceae was undertaken to provide a compre­ presented the mid-point of the latitudinal range hensive anatomical description of the family, estimated from available taxonomic and floris­ to outline basic trends of anatomical specialisa­ tic literature. Although precise collecting data tion, and to provide data that may eventually were available for only 15 percent of the sam­ contribute to a better understanding of the ples, the latitudes for 80 percent of the samples evolution and systematics of the group. An ear­ were estimable to within a 10° range. lier paper dealt with leaf anatomy (Schadel & Skewness and kurtosis were assessed for each Dickison, 1979). variable and all statistical calculations were per­ formed using SAS. Data for vessel and ray fre­ Materials and Methods quency, vessel element and fibre diameter, ves­ Woods of just over forty species of Styraca­ sel wall thickness, number of bars per perfora­ ceae (s.s.) were studied. Wood samples could tion plate, fibre pit diameter, and ray height not be obtained for the Brazilian genus Pam­ and width were log-transformed to reduce philia Martius ex A. DeCandolle and only a skewness. Pearson product-moment correlation small twig sample was available of Parastyrax coefficients were computed for all pairs of vari­ lacei. It should also be noted that many of the ables. wood samples of Chinese origin are apparently All variables showing correlation with lati­ without adequate documentation. Nevertheless, tude significant at the 10 percent level were most of these samples currently represent the subjected to multiple regression analyses in or­ only available specimens for a few styracaceous der to further clarify the relationship between genera and species and there is no reason to latitude and each of the highly intercorrelated doubt their authenticity. Xylaria abbreviations variables. Significance of correlation of each follow the suggestions of Stern (1978). variable with latitude after regression on all Samples were prepared in the usual manner other variables is shown in Table 2 (see p. 16). by boiling and storage in equal parts glycerine In the generic descriptions the measurements and 50% alcohol. Sections were cut at between for vessel element length, pore diameter, scala­ 15-20 J.l.ITI and stained with safranin. All statis­ riform perforation plate bar number, and im­ tical data regarding cell length (Table I) were perforate tracheary element are listed as three gathered from macerations prepared using Jef­ or four separate numbers. The numbers in pa­ frey's macerating fluid. Silica distributions rentheses are the extremes measured in all the were studied with a combination of scanning specimens examined and the remaining number electron microscopy (SEM) and light micro­ or numbers represent the average or range of scopy, using radial sections that were left un­ averages for all species. All measurements have stained but bleached with a commercial strength been rounded off to the nearest whole micron. bleach. Both crystals and silica were clearly vis­ ible in such preparations. For each sample twenty-five measurements Results were made of vessel element length (including ligules), diameter, number of bars per perfora­ Generic wood descriptions tion plate, and imperforate element length and Statistical data ofStyracaceae wood anatomy diameter. Ten measurements per sample were are summarised in Table I (data on Parastyrax made of vessel wall thickness, in tervessel pit are not included in the table because of the diameter, fibre wall thickness and pit diameter, juvenile nature of the material studied). multiseriate ray height and width, and uniseriate ray height. It should be noted that in some in­ Alniphyllum Matsumura stances fibre pit borders are very reduced which Number of species: 8. made measurements difficult. The entire ray Distribution: Southwest China, Indochina, height was counted or measured. Counts in ten Formosa. one mm 2 fields per sample were made to deter­ Material studied: A. fortunei Perk., China: mine pore and ray frequency. Pore frequencies (MAD-SJRw 21904), (MAD-SJRw 21923); Hai­ were counted on the transverse section whereas nan: (MAD-SJRw 29560). - A. pterospermum ray frequencies were counted from tangential Matsum., Formosa: (TAIFw s.n.), Kanehira 46 sections. Rays that were only partially in the (MAD-SJRw 6447). field of count were tabulated. Measurements Growth rings distinct, represented by narrow encompassed both early and late wood when zones of radially flattened fibre-tracheids. Pores present. distributed in aggregate radial rows isolated Latitude was determined from collection from adjacent rows by regions devoid of pores data whenever possible. When such determina­ (Fig. I). Vessels both infrequently solitary and tion was not possible, the latitude assigned re- in long radial multiples, angular in outline, tan-

Downloaded from Brill.com10/07/2021 04:17:38AM via free access IAWA Bulletin n.s., Vol. 6 (1),1985 7 gential diameter (30-)59-72(-100) p.m. Ves­ Halesia Ellis ex Linnaeus sel element length (858-)1317-1370(-2272) Number of species: 3-5. p.m. Perforations scalariform with up to 24 nar­ Distribution: Eastern Asia, southeastern Uni­ row bars per plate. Intervessel pits mostly op­ ted States. posite to alternate, round in outline, most fre­ Material studied: H. carolina L., Adcock 75 quently 6-8 J.Lm in diameter. Vessel-ray pitting (MADw 35851), (PRFw 3509). - H. diptera similar but half-bordered. Tyloses absent. Im­ Ellis, (MAD-SJRw 43450), (PRFw 12904), Mis­ perforate tracheary elements (1060-) 1919- sissippi: Koehler 34 (MADw 2933), Florida: 2080( -2696) J.Lm in length, with generally dis­ Anderson 99 (MAD-SJRw 45884). - H. mac­ tinct bordered pits equally distributed on both gregorii Chun, China: (MAD-SJRw 29811), radial and tangential walls. Imperforate element (MAD-SJRw 29815). pit diameter ranges between approximately 5- Growth rings distinct, irregularly spaced, re­ 9 p.m. Axial parenchyma apotracheal diffuse presented by zones of radially flattened fibre­ and diffuse-in-aggregates between 2-6 cells; tracheids, vessels narrower in diameter at the less frequently also paratracheal scanty. Rays termination of a growth increment. Vessels heterocellular; uniseriates composed predomi­ solitary and in radial multiples of 2-5 (6), oc­ nantly of square and upright cells; bi- and tri­ casionally in clusters of 3-4, angular to circu­ seriate rays with uniseriate marginal extensions lar in outline, tangential diameter (25-)50-55 of mostly erect cells and a central portion of (-82) p.m. Vessel element length (535-)905- procumbent cells (Figs. 2, 3). Crystals of cal­ 963(-1494) J.Lm. Perforations scalariform with cium oxalate absent. Silica bodies absent. up to 20 narrow bars per plate. Intervessel pits mostly opposite, round in outline, diameter Bruinsmia Boerlage & Koorders most frequently 6-8 p.m. Vessel-ray pitting Number of species: I or 2. similar but half-bordered. Tyloses absent. Im­ Distribution: Assam, Burma, Malaysia (ex­ perforate tracheary elements (949-) 1385- cluding Malay Peninsula). 1453(-2090) J.Lm in length, with indistinctly Material studied: B. styracoides Boerl. & to distinctly bordered pits on both radial and Koord., Java: (MAD-SJRw 31236); New Gui­ tangential walls. Imperforate element pit dia­ nea: BW 6000 (USw 32003), CSIRO (USw meter ranges between approximately 3-7 p.m. 34785), CSIRO (USw 35256), CSIRO (USw Axial parenchyma diffuse and diffuse-in-aggre­ 35289). gates of 2-5 cells, also occasional paratracheal Growth rings absent. Vessels solitary and in scanty. Rays heterocellular, uniseriates com­ radial mUltiples of 2-3, rarely clusters of 3, posed of mostly square and procumbent cells mostly circular in outline, tangential diameter (upright cells common in H. macgregorii); mul­ (67-)158(-212) p.m. Vessel element length tiseriates with uniseriate marginal extensions of (747-)1520(-2272) p.m. Perforations scalari­ square and occasionally upright cells and a form with (10-)15(-33) bars per plate. Inter­ central portion of procumbent cells. The hete­ vessel pits mostly alternate, some transitional rocellular condition is more pronounced in H. between opposite and alternate, round in out­ macgregorii. Prismatic crystals of calcium ox­ line, mostly 10 p.m in diameter. Vessel-ray pit­ alate of sporadic and infrequent occurrence in ting similar but half-bordered. Tyloses absent. chambered axial parenchyma cells in H. caro­ Imperforate tracheary elements (1373-)2469 lina and H. diptera. Silica bodies absent. (-3484) J.Lm in length, with indistinctly to dis­ tinctly bordered pits that are more abundant Huodendron Rehder on the radial walls. Imperforate element pit Number of species: 6. diameter ranges between approximately 3-7 Distribution: Southern China, Thailand, In­ p.m. Axial parenchyma mostly diffuse and dif­ dochina. fuse-in-aggregates between 2-6 cells, also occa­ Material studied: H. biaristatum var. parvi­ sionally paratracheal scanty. Rays heterocellu­ flora (W. W. Smith) Rehder, China: Tang (MAD­ lar, uniseriates composed of square and upright SJRw 22029). cells; multiseriates 2-6 cells wide with unise­ Growth rings distinct, evenly spaced, repre­ riate marginal extensions of upright cells and a sented by narrow zones of radially flattened central portion of procumbent cells. Crystals of fibre-tracheids. Vessels predominantly solitary calcium oxalate in the form of prisms and small, (93%), or in infrequent radial multiples of 2-4, irregular clusters present in chambered axial rarely in clusters of 3, circular in outline (Fig. 9), parenchyma cells, and also rarely in ray paren­ tangential diameter (45-)57(-72) !lm. Vessel chyma. Axial parenchyma cells often with both element length (737-) 1153 (-1494) !lm. Per- transverse and vertical septations resulting in multiple crystal chambers. Silica bodies absent. (text continued on page 12)

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Fig. 1-6. Wood anatomy of Styracaceae and Lissocarpaceae. - Fig. 1-3. Alniphyllum fortunei (MAD-SJRw 21904). - I: Transverse section showing radial pattern of vessel distribution. - 2: The same, tangential section. - 3: The same, radial section showing heterocellular ray. - Fig. 4 -6. Lissocarpa guianensis (PRFw 17105). - 4: Transverse section showing radial pore multiples and prominent narrow-banded distribution of axial parenchyma. - 5: The same, tangential section. 6: The same, tangential section showing mostly opposite intervessel pitting.

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Fig. 7-10. Wood anatomy of Styracaceae. - Fig. 7 & 8. Sinojackia xyiocarpa (MAD-SJRw 29823). 7: Transverse section illustrating pores distributed in radial zigzag lines. - 8: The same, tangential section. - Fig. 9 & 10. Huodendron biaristatum var. parvi[lora (MAD-SJR 22029). - 9: Transverse section showing solitary pore distribution. - 10: The same, tangential section.

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O.lmm ~ -- ~ ff 11.12.13.15.16 J[ ~~

}1 /" "\ ~ If

tlIlr f- A~ I-' ff -" ~ ~ 1 ~ ~ . ~ ~ K ,~N ~ H: ~ ("l'~ r~~: f .

Fig. 11-17. Wood anatomy of Styrax. - 11: S. americanus (PRFw 12944), TrS showing growth ring and pore multiples. - 12: The same, TgS. - 13: S. pa/lidus (MADw 35861), TrS. - 14: The same, TgS, showing mostly alternate intervessel pitting. - 15: The same, TgS. - 16: S. odoratissimum (MAD-SJR w 21921), TrS in the vicinity of a growth ring. - 17: The same, TgS, showing prismatic crystals (arrows) in the ray parenchyma.- TrS: transverse section; TgS: tangential section.

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Fig. 18-23. Wood anatomy of Styrax. - Fig. 18-20. S. officinalis (SJRw 47817). - 18: Trans­ verse section showing semi-ring-porous condition. - 19: The same, tangential section. - 20: The same, radial section showing crystalliferous axial parenchyma strand. - Fig. 21-23. S. platanifolius (USw 19556). - 21: Transverse section showing ring-porous condition. - 22: The same, tangential section. - 23: The same, radial section showing simple perforation plate (arrow) next to scalariform plate with two thick bars.

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26 . 0.5 mm ~ 25. 26

Fig. 24-26. Wood anatomy of Styrax. - Fig. 24 & 25. S. tarapotensis (MAD-SJRw 39673). - 24: SEM of radial section illustrating solitary silica grains (s) in the upright ray cells, x 800. - 25: The same, light microscopy of radial section showing silica grains (arrows) in the ray parenchyma. - Fig. 26. S. hypochryseus (USw 26822), light microscopy of radial section showing prismatic cal­ cium oxalate crystals (c) in axial parenchyma cells and silica grains (arrows) in the ray parenchyma.

forations scalariform with (19-)29(-35) bars Melliodendron Handel-Mazzetti per plate. Intervessel pits opposite, round in Number of species: 3. outline, diameter approximately 4 J.J.II1. Vessel­ Distribution: Southern and southwestern ray pitting similar but half-bordered. Tyloses China. absent. Imperforate tracheary elements (1242-) Material studied: M. wangianum Hu, China: 1873(- 2424) iJ.m in length, with indistinctly (MAD-SJRw 29824). -M. xylocarpum Hand.­ to distinctly bordered pits on both radial and Mazz.,China: (MAD-SJRw 29796), (MAD-SJRw tangential walls, pitting occasionally bi- and tri­ 29797). seriate. Imperforate element pit diameter ranges Growth rings distinct, unevenly spaced and between approximately 3-6 iJ.m. Axial paren­ often wavy, represented by narrow zones of ra­ chyma diffuse and diffuse-in-aggregates between dially flattened fibre-tracheids. Pores often dis­ 2-3 cells, also para tracheal scanty (Fig. 9). tributed in zigzag radial lines or aggregations, Rays heterocellular (Fig. 10); uniseriates com­ particularly in M. xylocarpum. Vessels solitary posed of upright cells; multiseriates up to 7 cells and in radial multiples of 2-7 (8) and clusters wide, with very long uniseriate marginal exten­ of 3-5, angular to circular in outline, tangential sions of generally upright cells and a central diameter (27-)64-76( -92) iJ.m. Vessel element portion of procumbent cells. The central multi­ length (454-)847-1015(-1323) iJ.m. Perfora­ seriate portion often with enlarged marginal tions scalariform with (5-)11(-21) bars per plate. cells, sometimes forming an incomplete sheath. Intervessel pits transitional between opposite Crystals of calcium oxalate absent. Silica bodies and alternate, round in outline, diameter most absent. frequently 6-8 iJ.m. Vessel-ray pitting similar

Downloaded from Brill.com10/07/2021 04:17:38AM via free access IAWA Bulletin n.s., Vol. 6 (1),1985 13 bt;t half-bordered. Tyloses absent. Imperfo­ opposite, round in outline, diameter most fre­ rate tracheary elements (1040-) 1494 -1717(- quently 6-8 J-lm. Vessel-ray pitting similar but 2434) J..UIl in length, with indistinctly to dis­ half-bordered. Tyloses absent. Imperforate tra­ tinctly bi-bordered pits more or less equally cheary elements (858-) 1406-1829(-2282) distributed on both radial and tangential walls. J-lm in length with indistinctly to distinctly bor­ Imperforate element pit diameter ranges be­ dered pits approximately equally distributed tween approximately 5-7 J..UIl. Axial parenchy­ on both radial and tangential walls. Imperforate ma diffuse and paratracheal scanty, occasionally element pit diameter ranges between approxi­ diffuse-in-aggregates between 2-3 cells. Rays mately 3-7 J..UIl. Axial parenchyma diffuse and heterocellular of two sizes; uniseriates composed diffuse-in-aggregates between 2-4 cells, also of mostly square and erect cells (infrequently para tracheal scanty. Rays weakly heterocellU­ also procumbent); multiseriates up to 5 cells lar, uniseriates composed of procumbent and wide, with uniseriate marginal extensions of square cells; bi- and triseriate rays with uni­ mostly square and erect cells and a central por­ seriate marginal extensions of procumbent, tion of predominantly procumbent cells. Crys­ square and occasionally erect cells and a central tals of calcium oxalate absent. Silica bodies ab­ portion of procumbent cells. Crystals of cal­ sent. cium oxalate absent. Silica bodies absent.

Parastyrax W. W. Smith Rehderodendron Hu Number of species: 2. Number of species: 10. Distribution: Burma and southern China. Distribution: China, Indochina. Material studied: P. iacei W. W. Smith, Burma: Material studied: R. kwangtungense Chun, Lace 5340 (E), young stem, diam. 4 mm. China: Tang 945 (MAD-SJRw 29813). - R. Growth rings not evident in young stem. Ves­ tsiangi Hu & Cheng, China: Tang (MAD-SJRw sels solitary and in radial multiples of 2-5 and 29827). - Rehderodendron sp., China: (PRFw clusters of 3-6, angular to more commonly cir­ 14749); Tang 931 (MAD-SJRw 29809). cular in outline. Perforations scalariform with Growth rings distinct, unevenly spaced and up to 17 bars per plate. Intervessel pits oppo­ wavy in outline, represented by zones of radial­ site to commonly transitional to alternate, ly flattened fibre-tracheids. Vessels solitary and round to slightly elongate in outline. Vessel-ray in radial mUltiples of 2-6 and clusters of 3-6, pitting similar. Tyloses absent. Imperforate angular to circular in outline, tangential dia­ tracheary elements with generally indistinctly meter (25-)48-58(-75) J..UIl. Vessel element bordered pits primarily on the radial walls. length (323-)835-1021(-1424) J-lm. Perfora­ Axial parenchyma diffuse, diffuse-in aggregates tions scalariform with (4-)10-12(-20) bars between 2-3 cells, and also occasionally para­ per plate. Intervessel pits mostly opposite with tracheal scanty. Rays heterocellular; uniseriates some transitional to alternate, circular in out­ composed of erect cells; multiseriates with uni­ line, diameter most frequently 6-7 J..UIl. Vessel­ seriate marginal extensions of upright cells and ray pitting similar but half-bordered. Tyloses a central portion of both erect and procumbent absent. Imperforate tracheary elements (939-) cells. Crystals and silica not observed. 1346-1577(-2151) J..UIl in length, with indis­ tinctly to distinctly bordered pits on both radial Pterostyrax Siebold & Zuccarini and tangential walls. Imperforate element pit N urn ber of species: 7. diameter ranges between approximately 3-7 Distribution: Burma to Japan. J-lm. Axial parenchyma mostly diffuse and dif­ Material studied: P. corymbosus Sieb. & Zucco fuse-in-aggregates with 2-5 (6) cells, also para­ China: Hu (MAD-SJRw 21464). - P. hispidus tracheal scanty. Rays heterocellular; uniseriates Sieb. & Zucc., China: Tang 342 (MAD-SJRw composed of square and erect cells, multiseri­ 29793), (PRFw 1458), Tang 195 (MAD-SJRw ates with uniseriate marginal extensions of 21807), Chow 73 (MAD-SJRw 42564), Japan: square and erect cells and central portion of (UCw lOll), (UC 3132), Fujioka II (MADw­ procumbent cells. Crystals of calcium oxalate SJRw 13851), TOFO 12570 (USw 23748). absent. Silica bodies absent. Pith flecks scatter­ Growth rings present, unevenly spaced, re­ ed in all collections. presented by a zone of radially flattened fibre­ tracheids. Vessels solitary and in radial multiples Sinojackia Hu of 2-5 and clusters of 3-5, mostly circular in Number of species: 3. outline, tangential diameter (37-)56-64(- Distribution: Southern China. 100) J..UIl. Vessel element length (484-)968- Material studied: S. xyiocarpa Hu, China: 10 13( -·1414) J-lm. Perforations scalariform with Tang (MAD-SJRw 29823). (5-)12-14(-36) bars per plate. Intervesselpits Growth rings distinct, evenly spaced, repre-

Downloaded from Brill.com10/07/2021 04:17:38AM via free access 14 IAWA Bulletin n.s., Vol. 6 (1),1985 sented by narrow zones of radially flattened leprosus H. & A., Brazil: Lindeman & de Haas and thicker-walled fibre-tracheids. Pores fre­ 1061 (UW 12866), Lindeman & de Haas 1335 quently distributed in zigzag radial lines (Fig. 7). (Uw 13043), Lindeman & de Haas 1907 (Uw Vessels solitary and in radial multiples of 2-5 13403), Hatschbach et al. 13728 (Uw 13747), (6) and clusters of 3-6, angular to circular in Reitz 22443 (USw 25568), Reitz & Klein 7352 outline, tangential diameter (25-)45 (-60) j.LI1l. (MADw 21828), Mattos Filho (lPTw 6256), Vessel element length (606-)894(-1424)j.LI1l. Argentine: Min. of Agric. 329 (lPTw 403). - S. Intervessel pits opposite, circular in outline, longifolius StandI., British Guiana: For. Dept. diameter mostly 5 j.LI1l. Vessel-ray pitting simi 5578 (USw 26204). - S. obassia Sieb. & Zucc., lar but half-bordered. Tyloses absent. Imper­ Japan: (MAD-SJRw 16883), (PRFw 1478). - forate tracheary elements (858-) 1335 (-1666) S. odoratissimum Champ., China: Tang (MAD­ j.LI1l in length, with generally distinctly bordered SJR w 21921). - S. officinalis L., Israel: Scott pits on both radial and tangential walls. Imper­ (MAD-SJRw 47817), Chudnoff 18 (MAD-SJRw forate element pit diameter ranges between ap­ 48490). - Spa/lidus A.DC.,Venezuela: Williams proximately 5-7 j.LI1l. Axial parenchyma most 10531 (MADw 35860), Williams 10353 (MADw Iy diffuse, occasionally also diffuse-in-aggregates 35861), Williams 10330 (MADw 35862), Pit­ between 2-3 cells and paratracheal scanty. tier 809 (MAD-SJRw 34296). - S. parallelo­ Rays heterocellular (Fig. 8); uniseriates com­ neurus Perk., Malaya: (MAD-SJRw 50417), posed of both erect and procumbent cells; bi­ Sumatra: Jacobs 8142 (MADw 38206). -s. phi­ and triseriates with uniseriate marginal exten­ ladelphoides Perk., China: Tang (MAD-SJRw sions of erect and procumbent cells and a cen­ 29805). - S. platanifolius Engelm., Texas: Wil­ tral portion of procumbent cells. Crystals of son T-41 (USw 19556); Dorr & Nixon 1911 calcium oxalate absent. Silica bodies absent. (Tex), Dorr & Nixon 1909 (Tex). - S. polyan­ thus Perk., Costa Rica: Stork4165 (MAD-SJRw 38381), Stork 4232 (MAD-SJRw 38443). - S. Styrax Linnaeus polyneurus Perk., Costa Rica: Smith 176 (MAD­ Number of species: ca. 120. SJRw 35438). - S. polyspermum C.B. Clarke, Distribution: Eastern Asia (primarily in trop­ Burma: (PRFw 4743). - S. serrulatus Roxb., ical and subtropical areas), West Indies, South (PRFw 6277). - S. suberifolius H. & A. (PRFw and Central America, the Mediterranean region 15501), (PRFw 14768), (TAIFw s.n.). - S. tara­ (one species), and North America. potensis Perk., Bolivia: Krukoff 10827 (MAD­ Material studied: S. americanus Lam., Kische SJRw 39673). - S. texanus Cory, Texas: Dorr (PRFw 12944), North Carolina: W.e. Dickison & Nixon 1918 (Tex). - S. vidalianus Sleumer, s.n. - S. argenteus Presl, Mexico: Lopez 7555 Colombia: Cuatrecasas 21642 (MAD-SJRw (MEXU 117), Panama: Stern et al. 1993 (USw 44484). 33765). - S. benzoin Dryand., Thailand: King Growth rings absent to distinct, when present 5464 (USw 32414), Malaya: (MAD-SJRw represented by narrow to broad zones of radial­ 49535). - S. camporum Pohl, Brazil: Eiten ly flattened fibres. The last fonned latewood is 1097 A (USw 24676). - S. fanshawei Sandwith, often devoid of pores (Fig. II). Wood mostly British Guiana: For. Dept. 5607 (USw 26207). diffuse-porous, infrequently semi-ring-porous - S. formosanus Matsum., Fonnosa: TAIFw or ring-porous (Figs. 18, 21). Vessels solitary s.n. (MAD-SJRw 6448). - S. glabratus Schott., and in radial multiples of 2-7 (8) and clusters Surinam: Lindeman 3862 (Uw 2840), Linde­ of 3-7, mostly circular in outline (Figs. II, 13, man 3901 (Uw 2875), Lindeman 4520 (Uw 16), tangential diameter (12-)43-111(-140) 3135), Lindeman 4532 (Uw 3143), Lindeman /lm. Vessel element length (191-)345-1193 4820 (Uw 3301), Lindeman et al. 513 (Uw (-1727) j.LI1l. Perforations scalariform with (1-) 21837), Schulz 7142 (Uw 4907), Heyligers 443 3-13(-26) bars per plate; bars comparatively (Uw 6626). - S. grandifolius Aiton, North Caro­ thick and widely spaced in S. officinalis, S. pla­ lina: Harrar (MAD-SJRw 49058). - S. guianen­ tanifolius, and S. texanus. In the distinctly ring­ sis A.DC., Brazil: Miranda Bastos 2197 (lPTw porous species of S. platanifolius and S. texanus 8960), Krukoff 6736 (MAD-SJR w 36853), Brit­ both simple and scalariform perforation plates ish Guiana: Smith 2577 (Mad -SJR w 35610), occur (Fig. 23). Simple plates are restricted to Surinam: Maguire 24424 (MAD-SJRw 44126), the wide, earlywood elements whereas scalari­ Venezuela: Williams 15608 (MADw 35857). - fonn plates occur exclusively in the narrow, S. hypargyreus Perk., Venezuela: MERw 325 late wood vessel elements. This same condition (MADw 23999). - S. hypochryseus Perk., Vene­ has also been reported in S. officinalis var. cali­ zuela: Univ. de Los Andes 325 (USw 26822). - fornicum by Copeland (1938) and more re­ S. japonicus Sieb. & Zucc., Japan: (UCw 3131), cently in S. officinalis var. fulvescens by Bissing (PRFw 27968), (MAD-SJRw 14613). - S. (1976) and Carlquist (1980). Simple plates are

Downloaded from Brill.com10/07/2021 04:17:38AM via free access IA WA Bulletin n.s., Vol. 6 (1), 1985 15 oblique to more commonly transverse in orien­ lariform. Oblique simple perforations predomi­ tation. Intervessel pits either transitional be­ nate but scalariform plates with up to 25 very tween opposite and alternate or alternate (Fig. fine and closely spaced bars occur sporadically. 14), mostly round in outline, with a most fre­ Some vessel elements have simple and scalari­ quent diameter between 4-8 p.m. Vessel-ray form perforations at opposite ends. No distinc­ pitting similar but half-bordered. Solid, amor­ tion in size can be made between elements pos­ phous deposits present in the vessels of a num­ sessing simple or scalariform plates. Intervessel ber of species. Imperforate tracheary elements pits opposite, or transitional between opposite (464-)647-1892(-2535) p.m in length, with and alternate, round in outline, small, diameter generally very indistinctly to distinctly bordered mostly 4 p.m (Fig. 6). Vessel-ray pitting half­ pits on both radial and tangential walls. Imper­ bordered, unilaterally compound, mostly oppo­ forate element pit diameter ranges between ap­ site. Imperforate tracheary elements of the libri­ proximately 2-7 p.m. Axial parenchyma abun­ form fibre type, (1434-)2353(-2777) p.m in dant, diffuse, diffuse-in-aggregates between 2- length, with thick walls and sparse pitting. Axial 6 (7) cells, and para tracheal scanty. Parenchyma parenchyma distributed in regular uniseriate lines mostly uniseriate but sometimes bi- and (occasionally biseriate) bands and as paratra­ triseriate. Apotracheal parenchyma occasional­ cheal scanty (Fig. 21). Rays heterocellular (Fig. ly approaches the banded condition (Fig. 16); 5); uniseriates range between 3-21 cells high forming narrow terminal bands in S. suberifo­ and are composed of procumbent and square lius. Rays heterocellular (Figs. 12, 15, 19,22); or upright cells; biseriates range between II-55 uniseriates composed of erect, square, and pro­ cells in height and are composed of a mixture cumbent cells; multiseriates generally 2-5 cells of procumbent, square, and upright cells. The wide, with uniseriate marginal extensions of biseriate condition is often restricted to local­ square and erect cells and a central portion of ised regions along the ray body. Crystals and mostly procumbent cells. Marginal cells in S. silica a bsen t. officinalis sometimes erect forming incomplete sheaths. Crystals of calcium oxalate were ob­ served in all species except S. americanus, S. General summary of xylem anatomy of Styra­ grandifolius, S. polyneurus, S. polyspermum, caceae (s. s.) and S. tarapotensis. Crystal prisms are predomi­ Growth rings. - Growth rings occur in all nantly restricted to chambered axial parenchy­ genera except Bruinsmia. Growth rings range ma cells (Figs. 20, 26), infrequently also in ray from indistinct to prominent, evenly to irregu­ parenchyma (Fig. 17) as in S. hypargyreus, S. larly spaced, and when present are generally officinalis, and S. suberifolius. Silica bodies are recognisable by the presence of a narrow zone present in the following species: S. argenteus, of radially compressed and thicker-walled im­ S. fanshawei, s. glabratus, S. guianensis, S. hy­ perforate tracheary elements of the latewood. pargyreus, S. hypochryseus (Fig. 26), S. lepro­ Often the last several layers of late wood xylem sus, S. pallidus, and S. tarapotensis (Figs. 24, are distinguished by the absence of pores, or 25). Silica was not always present in all collec­ pores of reduced diameter. In some species the tions of a species, as in S. argenteus. The grains occurrence of growth rings is variable among are small (4-9 p.m) and round or irregular in different collections of the same species. Styrax shape with a granular surface, occurring as soli­ platanifolius and S. texanus are unusual among tary grains in the ray parenchyma. Although species examined as a result of their distinctly silica bodies may occur in both the procum­ ring-porous condition (Type IX growth ring of bent and upright ray cells, they are typically Carl quist, 1980), in which vessels are consider­ larger and more abundant in the square and up­ ably wider in diameter and more numerous in right cells. the early than latewood. A semi-ring-porous condition, in which the early wood is marked Lissocarpa Bentham by occasional large vessels, also characterises (Lissocarpaceae, sensu Gilg, 1924) plants of Halesia and Israeli plants of Styrax Number of species: 2. o fficinalis. Distribution: Tropical South America. Vessels. - Vessel element length ranges be­ Material studied: L. guianensis Gleason, Gui- tween species means of 345 p.m in Styrax texa­ ana: (PRFw 17105). nus and 405 p.m in S. platanifolius, up to 1520 Growth rings absent. Vessels solitary (24%) J.Lm in Bruinsmia styracoides. Most species have and in radial mUltiples and clusters of 2-9 (Fig. vessel elements ranging between 700-1200 p.m. 4), circular in outline, tangential diameter (37-) Mean pore diameter ranges between 43 p.m in 101(-145) p.m. Vessel element length (868-) Styrax texanus and S. platanifolius and 158 p.m 1148(-1464) p.m. Perforations simple and sca- in Bruinsmia styracoides. Small diameter vessels

Downloaded from Brill.com10/07/2021 04:17:38AM via free access Table 2. Correlation analysis· and regression analysis·· significance probability levels in Styracaceae (PR > F). -0\

LAT VFR VWT VEO URH MRH GR VEL MRF FO FL FPO BARS IVPO FWT URF

LAT .0001 .0001 .0001 .0001 .0001 .0001 .0001 .0005 .0006 .0010 .0117 .0198 .0355 .0562 .0883 VFR .0142 .0001 .0001 .0001 .0001 .0001 .0001 .0001 .0001 .0001 .0150 .0778 .4124 .0567 .0557 VWT .0188 .0001 .0001 .0001 .0001 .0002 .0001 .0018 .0003 .0253 .0136 .4408 .0001 .0104 VEO .1124 .0001 .0001 .0001 .0001 .0001 .0001 .0001 .8067 .7851 .3911 .0036 .0005 URH .4064 .0001 .0240 .0001 .0001 .0001 .0001 .0938 .1778 .0133 .2950 .7786 MRH .6044 .0096 .0007 .0001 .0007 .0038 .0422 .1299 .0743 .0302 .0043 GR .0995 .0031 .0282 .0054 .0028 .2168 .8602 .2158 .0688 .0511 VEL .0034 .0001 .0001 .0001 .0001 .0001 .0002 .0001 .0001 MRF .0136 .0001 .0001 .9541 .9878 .8727 .0041 .2649 FO .2500 .0001 .0001 .0001 .0001 .0084 .0004 FL .3346 .0001 .0001 .0001 .0001 .0001 FPO .0840 .0001 .0001 .0394 .0005 BARS .0998 .0001 .0020 .0358 IVPO .0982 .0688 .0001 ~ Downloaded fromBrill.com10/07/2021 04:17:38AM FWT .9627 .0003 > I:C URF .1512 § ~ S· ::; Values on upper right half table show correlation coefficient significance. * of 1-> ** Values in left vertical column show partial regression coefficient significance. <: Explanation of symbols: LAT, latitude; VFR, vessel (pore) frequency; VWT, vessel wall thickness; YEO, vessel element diameter; URH, uniseriate ray height; MRH, f?. multiseriate ray height; GR, growth rings; VEL, vessel element length; MRF, multiseriate ray frequency; FO, fibre diameter; FL, fibre length; FPO, fibre pit dia­ 0\ meter; BARS, number of bars per perforation plate; IVPO, intervessel pit diameter; FWT, fibre wall thickness; URF, uniseriate ray frequency. '-'- via freeaccess \0 00 '" IAWA Bulletin n.s., Vol. 6 (1),1985 17 characterise Sinojackia xylocarpa, Styrax ame­ ring-porous and simple perforation plates are ricanus, S. grandifolius, Halesia diptera and restricted to the wider, earlywood elements. plants of Rehderodendron. Generally there is Narrower latewood vessel elements possess only no significant difference in vessel diameter scalariform perforations. The scalariform plates throughout the growth ring, excepting the in these plants possess bars that are generally smaller, very last formed elements. Distinctly thicker and more widely spaced than is typical ring-porous woods occur only in a small num­ for the genus. All collections that were exam­ ber of Styrax species. In S. platanifolius, for ined of Israeli plants of Styrax officinalis con­ example, early wood pores average 67 J.LIl1 in tained only scalariform perforation plates. This diameter whereas latewood vessels have an observation is in agreement with the recent re­ average width of 26 J.LIl1. However, little differ­ port of Baas et al. (1983). ence in length is evident between early and The S tyracaceae are characterised by vessels late wood vessel elements. Wider, early wood that are distributed both as solitaries and pore elements with simple perforation plates average multiples. A distinctive radial pattern of vessel 391 J.LIl1 in length and the narrower late wood distribution occurs in Alniphyllum and vessels elements with scalariform perforation plates distributed in zigzag radial lines distinguishes average 407 J.LIl1 in length. These dimensions, Sinojackia xylocarpa. Huodendron is the only and those recorded for fibre-tracheid length, are genus in which vessels are nearly all solitary. Both similar to those reported by Copeland (1938) pore chains and clusters composed of 2-6, in­ for S. officinalis var. californicum. frequently up to 8, vessels, as well as solitary Pore outline is generally a combination of vessels, occur in the remaining genera with angular and circular. Predominantly circular somewhat varying percentages of each type. pores occur in the genera Bruinsmia, Huoden­ The percent solitary pores in all genera ranges dron and Styrax. Vessel wall thickness is typi­ mostly between 60-75%. cally thin, ranging between 2 and 3 J.LIl1, rarely Imperforate tracheary elements. - Im­ exceeding 4 /lm. Tyloses have not been observ­ perforate tracheary elements range from fibre­ ed in our material but dark-staining, occluding tracheids with distinctly bordered pits to ele­ deposits may occur in the apparently nonfunc­ ments having small, indistinctly bordered pits tional pores. Pore number ranges from moder­ that approach the simple condition. Pit apertures ately few (5-10 mm 2) in Bruinsmia styracoides are typically slit-like and crossed. Imperforate tra­ to very numerous (over 100 per mm 2) in Hale­ cheary elements are nonseptate and have mean sia diptera, Pterostyrax corymbosus, Rehdero­ species ranges between 647 J.LIl1long and 13 J.LIl1 dendron, and species of Styrax such as S. gran­ wide in Styrax texanus, and 2469 J.LIl1long and difolius, S. platanifolius, and S. texan us. 41 J.LIl1 wide in Bruinsmia styracoides. Imper­ Intervessel pitting is characteristically oppo­ forate elements mostly fall into the medium to site transitional to alternate; however, depend­ long category between 1300-1800 J.LIl1. Cell ing upon the species either an opposite or alter­ walls are mostly thin to medium in thickness. nate arrangement may predominate. Alternate Rays. - All genera possess a mixture of both pitting predominates in Bruinsmia and Styrax. multiseriate and uniseriate heterocellular rays. Intervessel pits are crowded and generally cir­ Multiseriates range in width between 2 and 7 cular in outline. Average species pit diameters cells and mean height between 14 and 29 cells. range between 4-10 J.LIl1, but are mostly 5-8 Uniseriates range between 3 and 8 cells in mean p.m. Vessel-ray pitting is similar except half­ height. Ray histology conforms to the hetero­ bordered. geneous I and II types of Kribs (1968). Occa­ With very few exceptions, perforation plates sional upright marginal cells forming incom­ are exclusively scalariform. Pamphilia, the only plete sheaths occur in the multiseriate rays of genus not examined, also apparently has scala­ Huodendron. riform perforations (Record & Hess, 1943). Axial parenchyma.-Axial parenchyma is Our observations do not support the report of rather uniformly distributed as a combination simple perforations in Bruinsmia by Metcalfe of diffuse, diffuse-in-aggregates with irregularly and Chalk (1950). Mean bar number ranges be­ distributed, mostly uniseriate (rarely bi- or tri­ tween 3 and 29. Bars are typically narrow, non­ seriated) tangential lines containing 2-7 cells, bordered, and closely spaced. Combinations of and paratracheal scanty. Parenchyma is most simple and scalariform plates were observed on­ abundant in species of the genus Styrax where ly in the Texas species Styrax platanifolius and apotracheal parenchyma occasionally approach­ S. texanus. This condition has also been report­ es the banded condition. ed in the two varieties of S. officinalis from Cry s t al s. - Prisma tic calcium ox ala te crystals California (Copeland, 1938; Carlquist, 1980). are present in species belonging to the genera These species are distinctly ring-porous or semi- Bruinsmia, Halesia, and Styrax. In Styrax, pris-

Downloaded from Brill.com10/07/2021 04:17:38AM via free access 18 IAWA Bulletin n.s., Vol. 6 (1),1985

•

...... • • .. .. : ...... • -...... ~L-__~ __~----L----L--~ __--~--~~~~--~--~ o 20 40 60 80 100 120 140 160 180 200 27 VESSEL FREQUENCY / mm 2

50

w , o 0·0 . :::J .. I- ... . . !;i- 30° ...... J ...... 00 f " " o .6.7.8.9 1.0 LI 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 28 LOG OF VESSEL FREQUENCY / mm 2

Fig. 27 & 28. Latitude and vessel-frequency in Styraceae. - 27: Relationship of vessel frequency and latitude. - 28: Log values of same data plotted in Figure 27.

Downloaded from Brill.com10/07/2021 04:17:38AM via free access IAWA Bulletin n.s., Vol. 6 (1),1985 19

matic crystals occur in the majority of species Additional points of difference between Para­ examined; however, crystals are not always styrax and other taxa of the Styracaceae include present in all samples of a taxon. Reports of an unusual height of 150 feet or more and dru­ the absence of crystals, therefore, may be the paceous fruit with a glabrous, fleshy exocarp result of insufficient sample size. Crystals are marked with elongate, whitish lenticels (Smith, generally borne in chambered axial parenchyma 1920). Although only a single twig sample of cells. Bruinsmia styracoides has crystalliferous Parastyrax was available for study, qualitative parenchymatous strands that are often sub­ characters of the secondary xylem appear con­ divided both horizontally and vertically. Crys­ sistent with other members of the family. tals are also infrequently located in ray paren­ Baas (1972) presented abundant evidence for chyma, as in Bruinsmia styracoides, Styrax hyp­ the removal of Afrostyrax Perkins & Gilg from argeus, S. officinalis, and S. suberifolius. Miller the Styracaceae and for its subsequent place­ (1976) reported that tropical members of Styrax ment in the family Huaceae. As noted by Baas, tend to accumulate more crystals than the tem­ significant wood anatomical differences be­ perate species. tween Afrostyrax and Styracaceae include ves­ Silica. - Silica grains occur in combination sel perforations simple in Afrostyrax, scalari­ with calcium oxalate crystals in a number of form in Styracaceae; axial parenchyma multi­ species of Styrax. Styrax tarapotensis is the on­ seriate banded in Afrostyrax, diffuse-in-aggre­ ly species examined in which silica is present gates and scanty in Styracaceae; fibres with and calcium oxalate absent. All species that simple pits in Afrostyrax, fibres with indistinct­ have thus far been confirmed as possessing silica ly bordered pits in Styracaceae. Additional fea­ are confined to the N eotropics. Not all collec­ tures distinguishing these two taxa are present­ tions of a species may possess silica as illustrated ed by Baas (I. c.). by S. argenteus, in which a specimen collected The genus Lissocarpa, also removed from the in Mexico was positive for silica whereas two Styracaceae by Perkins (1907), has subsequent­ collections from Panama were without silica ly been generally regarded as constituting the depositions. As reported by Ter Welle (1976), closely related monogeneric family Lissocarpa­ silica is restricted to the ray parenchyma cells. ceae (Gilg, 1924; Hutchinson, 1959; Wagenitz, 1964; Cronquist, 1981). In addition to repro­ Discussion ductive characters, Schadel and Dickison (1979) Wood anatomy of Styracaceae is qualitative­ described the following features of foliar anato­ ly rather uniform. Features present in almost my that can be used to separate Lissocarpa from all species include exclusively scalariform per­ Styracaceae: diffuse, branched sclereids in the foration plates, pores occurring as both soli­ petiole and mesophyll, petiole vascularisation taries and pore multiples, intervessel pits ar­ consisting of an arc with outwardly curving ranged in an opposite to alternate manner, ends, and fimbriate marginal ultimate venation. fibres with indistinctly to distinctly bordered In addition, the xylem of Lissocarpa differs pits, both multiseriate and uniseriate heterocel­ from the S tyracaceae by possessing vessel ele­ lular rays, and axial parenchyma distributed as ments with both simple and scalariform per­ a combination of diffuse, diffuse-in-aggregates foration plates, and prominently banded axial and scanty. Prismatic crystals and silica occur parenchyma. in a number of species but are not present in An interesting aspect of styracaceous wood all genera. structure is the occurrence of simple perfora­ In accordance with the widely accepted tions in a few species of Styrax in an otherwise trends in wood evolution as reviewed by Bailey entirely scalariform perforation plate family. (1957), Carlquist (1961), and Dickison (1975), This feature was apparently first described by the occurrence of more primitive features of Copeland (1938) in plants of S. officinalis var. predominantly solitary pore distribution and californicum, although for the most part it has the presence of comparatively high bar number been overlooked in subsequent descriptions of on the scalariform perforation plates in Huo­ the family. Bissing (1976) and Carlquist (1980) dendron are of potential evolutionary signifi­ reported the presence of simple plates in S. of cance. Any phylogenetic speculation, however, ficinalis var. fulvescens and we are now also must await study of additional specimens. documenting the occurrence of simple plates in Schadel and Dickison (1979) commented the wider, early wood vessel elements of S. pla­ upon the unique foliar structure of the genus tanifolius and S. texanus. All of these plants Parastyrax, as compared with other Styraca­ occupy seasonally dry habitats in portions of ceae, including a distinctive petiolar vascularisa­ the southwestern and western United States. tion, actinodromous primary venation, and the Styrax texan us is found in the plateau region presence of crystal sand in the leaf mesophyll. of central Texas where it typically grows on

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the sides of steep limestone cliffs. Styrax piata­ temperate ones (such as S. americanus. S. grandi­ nifolius, another species from central Texas, al­ folius. S. japonicus, and S. obassia), indicating so grows on highly calcareous soils in dry, that mesic-xeric trends can override latitudinal wooded bottomlands and on rocky banks and trends. It is also interesting to note that within cliffs (Gonsoulin, 1974). the family as a whole, the tall tropical tree spe­ Our observations are in agreement with Baas cies Bruinsmia styracoides possesses vessel ele­ et al. (1983) as regards the presence of exclu­ ments and fibres of the greatest dimensions. sively scalariform perforation plates in plants Wood anatomical data were subjected to sta­ of Styrax officinalis from Israel, albeit with re­ tistical analysis to determine which, if any, fea­ duced bar number and thickened bar width. tures are correlated with latitude of provenance. However, California plants presumably belong­ A portion of the results of the correlation anal­ ing to the same species, have evolved both sim­ ysis is included in Table 2. Vessel element fre­ ple and scalariform perforations. Gonsoulin quency as well as multiseriate ray frequency (1974) commented upon the rather confused show significant positive correlation with in­ nomenclatural history of the S. officinalis com­ creasing latitude, whereas vessel element length, plex and found the differences between the vessel wall thickness, pore diameter, multiseriate Mediterranean and California material signifi­ and uniseriate ray height, and fibre-tracheid cant only at the varietal level. Accordingly, the length and diameter show significant negative differences in perforation plate type within correlation with increasing latitude at the .01 % what appears to be varieties of the same species level. Growth rings are also more common in is of special interest. It would be particularly temperate as opposed to tropical species. Fibre­ interesting to determine to what extent this tracheid pit diameter, intervessel pit diameter, character is genetically stable. and the number of bars per scalariform perfora­ The occurrence of reduced scalariform per­ tion plate are significantly correlated with in­ foration plate bar numbers and even simple creasing latitude at the .05 % level, and fibre­ perforations in species of Styrax from localities tracheid wall thickness and uniseriate ray fre­ with long dry periods correlates with similar quency at the .1 % level. Of the variables posi­ specialisations observed in other plants growing tively correlated with latitude at the .01 % sig­ in xerophytic conditions (Baas et aI., 1983; nificance level, all show strong (.01% level) cor­ Carlquist, 1975; Dickison, 1979; Dickison etal., relation with each other with the exception of 1978). Van den Dever et al. (1981), however, growth rings and uniseriate ray height and found that the considerable variation in bar growth rings and multiseriate ray frequency. number in Sympiocos could not be interpreted Of the variables showing correlation with la­ in terms of water availability. titude at the .5 % or 10% levels, all show strong Carlquist (1980) speculated that the type of (.0 I % level) correlation with at least three of growth ring in which wider vessels from the the variables showing a strong correlation (less earlywood possess simple perforation plates is a than or equal to .1 % level) with latitude. A potential accommodation to the flow of greater multiple regression analysis was performed for volumes of water per unit time earlier in the each variable in order to clarify the effects of season. The presence of scalariform perforations intercorrelation. Table 2 demonstrates signifi­ in the latewood elements was not regarded as cance levels for the partial correlation coeffi­ being disadvantageous as a result of slower rates cients of each variable with latitude after re­ of water movement in latewood. Although gression of all other variables. Eight variables these ideas were only offered as hypotheses, were significant at the 10% or less level. Growth the trend from exclusively scalariform to a rings and fibre-tracheid pit diameter failed to combination of scalariform and simple perfora­ meet the 5 % level of probability in any of the tions in Styrax appears clearly to be a response regression models tested in a procedure in which to drier conditions. Additional xerophytic obtaining the maximum R 2 (a measure of close­ adaptations present in Styrax woods include ness of fit of a model) was the main criterion vessels that are overall narrower in diameter, (MAXR option of GLM). Remaining variables shorter in member length, and more numerous were significant at the 5 % level or less in at per unit area. Baas et al. (1983) found that the least eleven models. It is interesting to note Mediterranean Styrax officinalis had a more or that vessel diameter and uniseriate ray height less identical vessel member length as the cool were also significant at the 5 % level in eleven temperate species studied by Van der Graaff or more models. Even the variables with partial and Baas (1974); however, in our more exten­ correlation coefficients significant only at the sive materials the xeric species of Styrax (s. offi­ 25 % level or more were significant at the 5 % or cinalis, S. piatanifolius. S. texan us) show some­ less level in at least one of the models, with the what shorter vessel members than the mesic cool exception of fibre-tracheid length, which like

Downloaded from Brill.com10/07/2021 04:17:38AM via free access IAWA Bulletin n.s., Vol. 6 (1),1985 21 fibre-tracheid pit diameter, and growth rings, Weak negative correlation is evident in Styra­ was not significant at the level in any of the caceae of latitude with ray height and fibre­ models tested. tracheid length, diameter, and wall thickness. The above analyses of wood features in In all of these features values decrease with in­ Styracaceae indicate that pore frequency, ves­ creasing latitude. Van den Oever et al. (1981) sel element length and wall thickness, and mul­ noted similar weak negative correlations in their tiseriate ray frequency show the strongest evi­ data on Symplocos. dence of correlation with latitude. Pore fre­ The trends reported here for Styracaceae quency and multiseriate ray frequency increase have now been generally confirmed in a large with distance from the equator whereas vessel number of diverse groups. As noted by Rury element length and wall thickness decrease. and Dickison (1984), what is now required is a Figure 27 shows the relationship of vessel fre­ better understanding of the relationship of xy­ quency and latitude and Figure 28 illustrates lem anatomy to other aspects of plants struc­ the log values of the same data. Similar correla­ ture and physiology. tions between pore frequency and vessel ele­ ment length with latitude have been reported Acknowledgements in a number of other taxa (Baas, 1973; Carlquist, We would like to thank Dr. Laurence E. Dorr 1966, 1982; van den Oever et aI., 1981; van der for collecting specimens used in this study. Graaff & Baas, 1974). Van den Oever et al. Appreciation is also extended to Dr. Robert K. (1981) demonstrated a decrease in vessel wall Peet for his very valuable comments on the thickness with increasing latitude in Symplocos, manuscript. The assistance of Dr. Regis B. Miller a situation also present in Styracaceae. It is is gratefully acknowledged. somewhat surprising that in light of the rather strong correlation between greater multiseriate References ray frequency with higher latitudes that exists Baas, P. 1972. Anatomical contributions to plant in Styracaceae, a similar condition is apparent­ taxonomy. II. The affinities of Hua Pierre ly not present in the other genera that have and Afrostyrax Perkins et Gilg. Blumea 20: been analysed in this manner. Carlquist (1966), 161-192. however, does mention an inverse correlation ~ 1973. The wood anatomical range in Hex between multiseriate ray frequency and lati­ (Aquifoliaceae) and its ecological and phylo­ tude in the Asteraceae. genetic significance. Blumea 21: 193-258. Variables for which correlation with latitude ~ , E. Werker & A. Fahn. 1983. Some ecolog­ is somewhat less strongly indicated include ical trends in vessel characters. IA WA Bull. pore diameter, intervessel pit diameter, number n.s. 4: 141-159. of bars per perforation plate, fibre-tracheid pit Bailey, I.W. 1957. The potentialities and limi­ diameter, and uniseriate ray frequency. Values tations of wood anatomy in the phylogeny for all but one variable increase with increasing and classification of angiosperms. J. Am. latitude. Only pore diameter decreases at higher Arbor. 38: 243-254. latitudes, a correlation that has been frequently Bissing, D. R. 1976. The effect of cultivation reported in other genera (Baas, 1973; Carlquist, on the expression of anatomical features of 1966, 1982; van den Oever et aI., 1981; van der the wood of selected dicotyledons. Ph.D. Graaff & Baas, 1974). Our finding of a latitudi­ Thesis, Claremont Graduate School, Clare­ nal trend toward increased intervascular pit size mont, California (not seen). from the tropics to more temperate regions is Carlquist, S. 1961. Comparative plant anatomy. opposite of what Miller (1976) reported for Holt, Rinehart & Winston, New York. Juglans. In the tropical black walnuts intervas­ ~ 1966. Wood anatomy of Compositae: A cular pits are larger in tropical species than summary, with comments on factors con­ temperate ones. trolling wood evolution. Aliso 6: 25-44. Carlquist (1982) noted an inverse correlation ~ 1975. Ecological strategies of xylem evolu­ between perforation plate bar number and lati­ tion. Univ. Calif. Press, Berkeley and Los tude for Illicium, as did Baas (1973) for !lex. Angeles. Van den Oever et al. (1981), however, observed ~ 1980. Further concepts in ecological wood no such condition for Symplocos. Van der anatomy, with comments on recent work Graaff and Baas (1974) list several examples of in wood anatomy and evolution. Aliso 9: positive correlation, negative correlation, and 499-553. no correlation with respect to variation in bar ~ 1982. Wood anatomy of Illicium (Illicia­ number and latitude, which led them to con­ ceae): Phylogenetic, ecological and func­ clude that there is no general trend in woody tional interpretations. Amer. J. Bot. 69: plants for this feature. 1587-1598.

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Chudnoff, M. 1956. Minute anatomy and iden­ Perkins, J. 1907. Styracaceae. In: Das Pflanzen­ tification of the woods of Israel. Ilanoth 3: reich IV, 241: 1-111 (ed. A. Engler). 37-52. Record, S.J. & R. W. Hess. 1943. Timbers of the Copeland, H.F. 1938. The Styrax of northern New World. Yale Univ. Press, New Haven. California and the relationships of the Sty­ Rury, P.M. & W.C. Dickison. 1984. Structural racaceae. Amer. J. Bot. 25: 771-780. correlations among wood, leaves, and plant Cronquist, A. 1981. An integrated system of habit. In: Contemporary problems in plant classification of flowering plants. Columbia anatomy (eds. R.A. White & W.C. Dickison): Univ. Press, New York. 495-540. Acad. Press, New York, London. Dickison, W.C 1975. The bases of angiosperm Schadel, W.E. & W.C. Dickison. 1979. Leaf phylogeny: vegetative anatomy. Ann. Mis­ anatomy and venation patterns of the Styra­ souri Bot. Gard. 62: 590-620. caceae. J. Am. Arbor. 60: 8-37. - 1979. A note on the wood anatomy of Dil­ Smith, W.W. 1920. Notes on certain Asiatic lenia (Dilleniaceae). IA WA Bull. 1979/2 & 3: Styracaceae. Notes Roy. Bot. Gard. Edinb. 57-60. 12: 231-236. - , P.M. Rury & G.1. Stebbins. 1978. Xylem Spongberg, S. A. 1976. Styracaceae hardy in anatomy of Hibbertia (Dilleniaceae) in rela­ temperate North America. J. Am. Arbor. tion to ecology and evolution. J. Am. Arbor. 57: 54-73. 59: 32-49. Stern, W.1. 1978. Index xylariorum. Institu­ Gilg, E. 1924. Lissocarpaceae. In: Syllabus der tional wood collections of the world. 2. Pflanzenfamilien, ed. 9 & 10 (eds. A. Engler Taxon 27: 233-269. & E. Gilg). Gebr. Borntraeger, Berlin. Sudo, S. 1959. Identification of Japanese hard­ Gonsoulin, G.J. 1974. A revision of Styrax woods. Bull. Govt. For. Exp. Sta., Meguro (Styracaceae) in North America, Central 118:1-138. America, and the Caribbean. Sid a 5: 191- Takhtajan, A.1. 1980. Outline of the classifica­ 258. tion of flowering plants (Magnoliophyta). Graaff, N.A. van der& P. Baas. 1974. Wood ana­ Bot. Rev. 46: 225-359. tomical variation in relation to latitude and Tang, Y. 1932-34. Timber studies of Chinese altitude. Blumea 22: 10 1-121. trees. I-IV. Bull. Fan Mem. Inst. BioI., Hutchinson, J. 1959. The families of flowering Peking 3: 127-131, 157 -210,253-338; plants. Clarendon Press, Oxford. ibid. 4: 209-268. -- 1973. The families of flowering plants. Ed. 3. Thorne, R. F. 1976. A phylogenetic classifica­ Clarendon Press, Oxford. tion of the Angiospermae. Evol. BioI. 9: Inokuma, T., K. Shimaji & S. Sudo. 1953. The 35-106. wood anatomical characters of Styracaceae Tortorelli, 1. A. 1956. Maderas y bosques ar­ in Japan. Bull. Tokyo Univ. Forests 45: gentinos. Editorial Acme, Buenos Aires 181-201. (not seen). Kanehira, R. 1921. Anatomical characters and Versteegh, C. 1968. An anatomical study of identification of Formosan woods. Govt. of some woody plants of the mountain flora Formosa, Taihoku. in the tropics (Indonesia). Acta Bot. Neerl. Kribs, D.A.1968. Commercial foreign woods on 17: 151-159. the American market. Dover PUbl. .. New Wagenitz, G. 1964. Lissocarpaceae. In: A. Eng­ York. ler's Syllabus der Pflanzenfamilien, ed. 12, Metcalfe, C. R. & 1. Chalk. 1950. Anatomy of Vol. 2. Angiospermen (ed. H. Melchior). the Dicotyledons. Clarendon Press, Oxford. Gebr. Borntraeger, Berlin. Miller, R. 1976. Wood anatomy and identifica­ Welle, B.J.H. ter. 1976. Silica grains in woody tion of species of J uglans. Bot. Gaz. 137: plants of the neotropics, especially Surinam. 368-377. In: Wood structure in biological and techno­ Moll, J. W. & H. H. J anssonius. 1906. Mikrogra­ logical research (eds. P. Baas, A.J. Bolton & phie des Holzes der auf Java vorkommenden D.M. Catling): 107-142. Leiden Bot. Ser. 3. Baumarten. E.J. Brill, Leiden. Leiden Univ. Press. Oever, 1. van den, P. Baas & M. Zandee. 1981. Wood Jr, CE. 1960. Styracaceae. In: The genera Comparative wood anatomy of Symplocos of the Ebenales in the southeastern United and latitude and altitude of provenance. States (eds. C.E. Wood Jr & R.B. Channell). IAWA Bull. n.s. 2: 3-24. J. Am. Arbor. 41: 1-35.

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