TAXON 49- FEBRUARY 2000 27
Wood and stem anatomy of Sarcobatus (Caryophyllales): systematic and ecological implications
Sherwin Carlquist’
Summary
Carlquist, S.: Wood and stem anatomy of Sarcobatus (C’aryophyllales): systematic and
ecological implications. — Taxon 49: 27-34. 2000. — ISSN 0040-0262. Quantitative and qualitative data are given for Sarcobatus vermiculatus (Hook.) Torr. stem anatomy in order to provide information relevant to Behnke’s segregation of Sarcobatus from Chenopodiaceae and his idea that Sarcobataceae belong in suborder Phytolaccineae rather than suborder Chenopodiineae. Sarcobatus has highly xeromorphic wood such as in xeric Chenopodiaceae (presence of vasicentric tracheids, narrow vessels, short vessel elements, numerous vessels per group, helical sculpturing of vessel walls), but these features could have evolved independently in both suborders. Nonbordered perforation plates, present in Sarcobatus, are widespread in C’aryophyllales s.str. and may prove to be a defining feature for the recently expanded Caryophyllales together with the neighbouring order Santalales. A single-layered lateral meristem occurs in genera of Chenopodiinae with successive cambia, but also in genera of Phytolaccineae. Likewise, raylessness occurs in both suborders. Stem and wood anatomy does not provide decisive evidence for placement of Sarcobatus in Phytolaccineae, but it does not provide any evidence against that treatment.
Introduction Behnke’s (1997) discovery of distinctive sieve tube plastids in Sarcobatus led him to remove the genus from Chenopodiaceae. In an earlier issue of this journal, Behnke (1997) assembled much information about the genus and suggested that the new family he created, Sarcobataceae, belongs in close proximity to Phyto laccaceae. Behnke (1997) cited evidence from DNA analyses (Clement & Mabry, 1996; Downie & al., 1995, 1997) for this treatment. In the suborder Phytolaccineae, Behnke (1997) includes Achatocarpaceae, Agdestidaceae, Aizoaceae, Barbeui aceae, Nyctaginaceae, Phytolaccaceae, Rivinaceae, Sarcobataceae, and Stegno spermataceae. This suborder is a modification of Phytolaccineae as recognized by Heimerl (1934) and Thorne (in Cronquist & Thorne, 1994). The segregate families were mostly treated as subfamilies of Phytolaccaceae by Thome (in Cronquist & Thorne, 1994). Information from wood anatomy is often significant with respect to the classification system. Compilations of wood data for Caryophyllales have been offered by Metcalfe & Chalk (1950) and by Gibson (1994). A series of monographs on wood of these families is in progress in order to offer more extensive information. These papers include Caryophyllaceae (Carlquist, 1995), Portu lacaceae and Hectorellaceae (Cariquist, 1998a), Petiveria and Rivina (Carlquist, 1998b), Basellaceae (Carlquist 1999a), Agdestis (Cariquist, 1999b), Stegno
1Santa Barbara Botanic Garden, 1212 Mission Canyon Road, Santa Barbara, California 93105, U.S.A.
1). Fig. vessels, below band (out focus of tissue conjunctive softer of buckling
plus 4) (Fig. cracks small in resulted tissues the conjunctive of hardness
the and stem, the of portions only best represented at sections microtome
The sliding (1985). Carlquist on is based tracheid vasicentric of concept the
(1964); Nomenclature on Committee IAWA the follow Terms tissue. conjunctive
not exclude do and transactions of scans random on based are diameter vessel
on figures The diameter. lumen vessel mean as measured was diameter Vessel
artifacts. numerous creating
walls, of distortion and expansion in resulted also sectioning better allowed that
of softening degree any because unsuccessful proved agents Softening impedance.
a further provide tissue conjunctive the in crystals soft; are stem the within
strands phloem yet the hard, very are tissue conjunctive of the fibers The problems.
microtechnical challenging exceptionally provide of Sarcobatus stems The
safranin.
with and stained acid) % chromic 10 and formalin % 10 parts Fluid (equal Jeffrey’s
of means by prepared were Macerations (SEM). microscope electron scanning
Nanolab & Lomb a Bausch with examined and coated, sputter stubs, aluminium
on mounted slides, clean between dried unstained, left were sections Other 9). 4,
1- slides (Figs. as permanent Balsam Canada in mounted and green combination fast
a safranin with stained were sections Some microtome. sliding a with prepared were
Sections ethanol. % 50 aqueous in preserved were stems The (RSA). 8038 Carlquist
1989, Jun 12 Co., California, Mono Lake, Mono of margins saline on the plants
from collected was diameter, in mm 8 to up vermiculatus, S. of material Stem
methods an4 Material
the order. as within as well Caryophyllales
outside genera from needed are their origin, of nature the as well as cambia,
successive these of products and action the concerning genera numerous more
from Details terminology. and interpretations various to subject been have families,
dicotyledon other of those as well as Caryophyllales, these of cambia successive
The cambia. has successive 1994), & Mabry, by Behnke as circumscribed order
(=
the s.str. Caryophyllales of genera and families other many like Sarcobatus,
order. the of systematics the to for comparison important more even becomes
wood data from adopted, is Caryophyllales of definition new broader If this (1994).
al. & Williams data of the on largely based 1998), (APG, Group Phylogeny sperm
Angio by the Polygonaceae) (Ancistrocladaceae, families allied and some ceae)
Nepentha (Droseraceae, glands digestive with families as as well Tamaricaceae)
Plumbaginaceae, (Frankeniaceae, glands salt with families to as include so widened
been recently has Caryophyllales of definition The years. recent in radically
most but 1994), & Thome, (Cronquist century past the over considerably changed
has of Caryophyllales concept The the order. for system classification the revising
in usable base data complete more a supply to undertaken been has Caryophyllales
of and genera families of This survey press). in (Cariquist, Phytolaccaceae rivinoid
and and phytolaccoid 1999d), (Carlquist, Barbeuia 1999c), (Carlquist, spermataceae
2000 49- FEBRUARY TAXON 28 TAXON 49- FEBRUARY 2000 29
— 1’ . . d i i ii ___I.1 •i ‘.
Figs. 1-4. Sections of stem of Sarcobatus vermiculatus. — I, transection from near surface of stem (top) inward; the lateral meristem is indicated by the pair of arrows; 2, transection of inner portion of stem, showing several vascular strands; arrows indicate terminus of a growth ring; 3, transection of vascular strand and adjacent tissues (f conjunctive tissue fibers, p = phloem, c = conjunctive tissue parenchyma); 4, tangential section, to show storied nature of phloem (darker vertical strand
to left of center) and lack of rays. — Figs. 1, 2, 4, magnification scale below Fig. 1 (divisions = 10 tim); Fig. 3, divisions = 10 jim.
is pattern storied this 4); (Fig. storied are walls lignified with tissue parenchyma
conjunctive and elements tube 4). Sieve Fig. in shown as of rays, criteria
the meet not do strands vascular between parenchyma or fibers tissue conjunctive
of (zones absent are Rays into strands. not subdivided is parenchyma Axial
tracheids. vasicentric or vessels with contact are in cells all parenchyma sparse,
moderately is 5, 6). parenchyma Axial (Figs. grooves the accompany ridges of pairs
vessels, the of many In 5-7). (Figs. apertures pit interconnecting grooves of form
the in is tracheids vasicentric and vessels of surfaces inner the on Sculpturing
7, right). (Fig. oval are apertures pit 7);
(Fig. diameter .im in 2.5 about are cavities pits, pit nonvestured bordered circular
have vessels of walls Lateral walls). thicker have vessels (wider m 2.0-4.0 about
thickness, wall Vessel nonbordered. simple, all plates Perforation sum. 93 length,
element vessel Mean 417. surveyed), area in included tissue (conjunctive transaction
of mm 2 per vessels of number Mean abundant. equally about are tracheids
vasicentric and vessels very narrow macerations, In tm). 20 diameter, lumen (mean
.tm 7 46 to from diameter in lumen range 7.3). Vessels group, per of vessels number
(mean multiples radial in grouped are 2). Vessels Fig. (arrows, observed were rings
growth a few xylem, the secondary 8). In (Fig. crystals elongate slender numerous
contains parenchyma Phloem cells. parenchyma tissue conjunctive the as length
same about the are 4) 3, (Figs. parenchyma phloem and elements tube Sieve
9). (Fig. crystals elongate three
to one contain cells
parenchyma the of Some 4 um). 244 (mean tissue conjunctive =
the of fibers the to compared .tm) 98 (mean short = relatively are cells parenchyma
The tissue. vascular of strands interconnect that bands tangential of the form
in occurs parenchyma 3). The (Fig. diameter lumen greater their of because starch
of quantities larger contain and walls lignified thinner have which cells, parenchyma
and starch; of amounts small contain and walls lignified thick relatively have which
fibers, cells: of kinds two of consists tissue conjunctive The tissue. conjunctive
the throughout scattered are 1) (Fig. or bands 2) (Fig. strands vascular These xylem.
secondary and phloem secondary which yields each of cambia vascular (successive)
at intervals, and, tissue conjunctive produces meristem lateral the interior, the To
crystals. elongate smaller separate of assemblage an or styloid a either bears which
of each idioblasts contains cortex secondary the cortex, primary the Like outside. the
to cortex secondary of files radial produces meristem lateral cortex. The inner the in
forms top, arrows) 1, (Fig. meristem A lateral stem. the of age on the depends which
of extent the cortex, primary of remnants are there stem, the of exterior the At
anatomy and stem Wood
cambia. successive with Caryophyllales
of on woods work monographic of lack the for account and 1986), at., & Fahn
by (see illustrations workers best the even by experienced been have podiaceae)
Cheno (e.g., these like woods of staining and sectioning in difficulties
Extraordinary 3 4. and Figs. in pale so relatively is and applied methods staining
in variations despite readily stain not did tissue conjunctive the Moreover,
2000 FEBRUARY 49 TAXON 30 TAXON 49- FEBRUARY 2000 31
A 1 8
Figs. 5-9. SEM photos (5-8) and light photomicrograph (9) from tangential sections of stem of
Sarcobatus vermiculatus (5-7 show inside surfaces of vessels). — 5, surface showing grooves interconnecting pit apertures, a pair of ridges parallels most of the grooves; 6, surface showing grooves interconnecting pit apertures and more pronounced ridges paralleling the grooves; 7, surface of vessel with fewer, inconspicuous ridges, outside surface of vessel at right shows nonvestured nature of pits; 8, crystals from a broken phloem parenchyma cell, to show narrow shapes and small sizes; 9, rhomboidal crystal (upper left) in parenchyma of conjunctive tissue. — Figs. 5-8. magnification scales at lower left (bar = 10 jim); Fig. 9, scale same as below Fig. 3.
developed an autapomorphy, be may Sarcobatus in occurrence the 1994), (Gibson,
Chenopodiaceae as such Caryophyllales other in occurs also sculpturing wall
vessel Although 1966). ones (Carlquist, xenc in represented well and is of habitats
range wide a occupies which in Asteraceae, of xeromorphy an indicator is vessels,
in sculpturing helical of forms other with together This, groove. each accompanying
ridges of pairs with often apertures pit interconnecting grooves of form the
takes sculpturing This surfaces. vessel on sculpturing helical of presence and 1985)
(Carlquist, tracheids vasicentric of presence include wood vermiculatus S. in morphy
xero indicate that features Qualitative wood. xeromorphic very a of indicative
is also (7.3) S. vermiculatus in group per of vessels number high The salinity. soil
of because xeric physiologically are especially that areas in desert grows Sarcobatus
but shrubs, desert California southern the for value the below certainly is 4.5. This
of Ratio a Mesomorphy has S. vermiculatus whereas 1985), & Hoekman, (Carlquist
20.9 is shrubs desert Californian southern Ratio for Mesomorphy The safety.
conductive also but efficiency conductive not only reflects ratio This mm 2 ). per
vessels by divided length element vessel times diameter (vessel Ratio Mesomorphy
the of form the in combined be can data vessel quantitative of kinds Three
Phytolaccineae. in belong Sarcobataceae that idea (1997) Behnke’s with consonant
is Barbeuia in Sarcobatus and in meristem lateral of type same the of occurrence
The families. and genera of terms in distribution the show will series this in
papers further and Caryophyllales, in occur types these of Both inside. the to tissue
conjunctive plus cambia vascular and outside the to cortex secondary produces
that thickness in cell a single only meristem a lateral has Barbeuia whereas 1999c),
(Carlquist, formation cambium successive for a precursor as cortex) secondary
in cells of files (radial meristem lateral a diffuse exemplifies Ste gnosperma
Carvophyllales s.str. in occur cambia to successive leading meristems lateral of
types Two interest. unusual of is Sarcobatus in meristem lateral the of nature The
press). in 1998b,
(Carlquist s.l. Phytolaccaceae of stem tissues other and in bark occur Sarcobatus,
in seen in bark, Styloids unpubi.). (Cariquist, Santalales order 1998) (APG, adjacent
the in Santalum does as plates, perforation nonbordered s.l.) have (Caryophyllales
Tamaricaceae example, For 1998). (APG, Caryophyllales expanded recently
the as well as 1994) Mabry, & Behnke by defined (as s.str. Caryophyllales for
symplesiomorphic thus and distribution, in ordinal be to prove may it character, this
to respect with known better is Caryophyllales order the When unpubi.). Cariquist,
Chenopodiinae; and Didiereaceae, of the (Alluaudia Portulacineae of genera
in occurs it also but in press), 1999b-d, (Carlquist Phytolaccineae in occurs authors,
by most neglected feature, This plates. perforation nonbordered has Sarcobatus
suborder. latter to the Sarcobataceae
assigned (1997) Behnke Phytolaccineae). (suborder Nyctaginaceae and Aizoaceae
(= in but also Chenopodiineae), suborder the Chenopodiaceae and Amaranthaceae
in occurs raylessness (1994) to Gibson according rayless; is Sarcobatus
conclusions and Discussion
tracheids. vasicentric and the vessels by shared
2000 FEBRUARY 49- TAXON 32 TAXON 49 FEBRUARY 2000 33
independently of the feature in other Caryophyllales. The unusually xeromorphic nature of wood of Sarcobatus should not be interpreted as indicating close relationship to Chenopodiaceae or other Caryophyllales with similarly xeromorphic woods. The placement of Sarcobatus by Behnke (1997) in suborder Phytolaccineae is entirely conceivable on the basis of the stem and wood anatomy data above, even though these data do not decisively place it in that suborder as opposed to placement in the other suborders of Caryophyllales s.str.
Literature cited APG (ANGIOSPERM PHYLOGENY GROUP). 1998. An ordinal classification for the families of flowering plants. Ann. Missouri Bot. Gard. 85: 53 1-553.
Behnke, H.-D. 1997. Sarcobataceae — a new family of CaryophyUales. Taxon 46: 495-507. — & Mabry, T. J. (eds.). 1994. Caryophyllales. Systeniatics and evolution. Berlin & Heidelberg. Carlquist, S. 1966. Wood anatomy of Compositae: a summary, with comments on factors influencing wood evolution. Aliso 6(2): 25-44. — 1985. Vasicentric tracheids as a drought survival mechanism in the woody flora of southern California and similar regions; review of vasicentric tracheids. Aliso II: 37-68. — 1995. Wood anatomy of Caryophyllaceae: ecological, habitat, systematic, and phylogenetic implications. Aliso 14: 1-17.
— 1998a. Wood anatomy of Porrulacaceae and Hectorellaceae: ecological, habital, and systematic implications. Aliso 16: 137-153.
— L998b. Wood and stem anatomy of Petiveria and Rivina (Caryophyllales): systematic implications. tnt. Assoc. WoodAnat. J. 19: 383-391. — 1 999a. Wood, stem, and root anatomy of Basellaceae, with relation to systematics and cambial variants. Flora 194: 1-12. 1999b. Wood anatomy of Agdestis (Caryophyllales): systematic position and nature of the successive cambia. Aliso 18: 35-43.
— 1999c. Wood and stem anatomy of Stegnosperma (Caryophyllales): phylogenetic relationships; nature of lateral meristems and successive cambial activity. tnt. Assoc. Wood Anal. J. 20: 149- 163.
— 1999d. Wood anatomy, stem anatomy, and cambial activity of Barbeuia (Carvophyllales). tnt. Assoc. Wood Anal. J. 20: 431-440.
— in press. Wood and stem anatomy of phytolaccoid and rivinoid Phyiolaccaceae (Caryophyllales): ecology, systematics, nature of successive cambia. Aliso. — & Hoekman, D. A. 1985. Ecological wood anatomy of the woody southern California flora. tnt. Assoc. WoodAnat. Bull., N. S. 6: 319-347. Clement, J. S. & Mabry, T. J. 1996. Chloroplast DNA evidence and family-level relationships in the Caryophyllales. Amer. J. Bot. 83(6, suppl.): 143. Cronquist, A. & Thorne, R. F. 1994. Nomenclatural and taxonomic history. Pp. 5-25 in: Behnke, H.-D. & Mabry, T. J. (eds.), Caryophyllales. Evolution and systematics. Berlin, Heidelberg & New York. Downie, S. R., Katz-Downie, D. S., & Cho, K-i. 1995. Structural and sequence variation in the highly conserved cpDNA inverted repeat region: implication for higher level taxonomic studies. Amer. J. Bot. 82(6, suppl.): 126.
— & — 1997. Relationships in the Caryophyllales as suggested by phylogenetic analyses of partial chloroplast DNA 0RF2280 homolog sequences. Amer. i. Bot. 84: 253-273. Fahn, A., Werker, E. & Baas P. 1986. Wood anatomy and identWcation of trees and shrubs from tsrael and adjacent regions. Jerusalem. Gibson, A. C. 1994. Vascular tissues. Pp. 45-74 in: Behnke, H.-D. & Mabry, T. J. (eds.), Caryophyllales. Evolution and systematics. Berlin, Heidelberg & New York. 34 TAXON 49- FEBRUARY 2000
— Heimerl, A. 1934. Phytolaccaceae. Pp. 135-164 in: Engler, A. & Prantl, K. (eds.), Die natUrlichen Pflanzenfamilien, ed. 2, I 6C. Leipzig. IAWA Commitee on Nomenclature. 1964. Multilingual glossary of terms used in wood anatomy. Winterthur. Metcalfe, C. R. & Chalk, L. 1950. Anatomy of the dicotyledons. Oxford. Williams, S. E., Albert, V. A. & Chase, M. W. 1994. Relationships of Droseraceae: a cladistic analysis of rbcL sequence and morphological data. Amer. .1. Bot. 81: 1027-1037.