WOOD ANATOMY of PAPAVERACEAE, with Commenth on VESSEL RESTRICTION PAVERNS
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JAWA Bulletin n.s., Vol.9 (3), 1988: 253—267 WOOD ANATOMY OF PAPAVERACEAE, WITH COMMENTh ON VESSEL RESTRICTION PAVERNS by Sherwin Cariquist and Scott Zona Rancho Santa Ana Botanic Garden and Department of Biology, Pomona College, Claremont, California 91711, U.S.A. Summary Qualitative and quantitative features are California, Dendrornecon is a conspicuous reported for Bocconia, Dendromecon, Di shrub or small tree to 6 m (Munz 1974). Boc centra, Hunnemannia, and Romneya. Boc conia, native to montane Mesoamerican and conia differs from the other genera by its Andean regions, is even taller (to 8 m: Fedde wide vessels, few per group, and few per 1936, Cumbie 1983), although the succulent mm2; it shows paedomorphosis in vessel ele cortex and pith suggest a degree of herbace ment length and ray histology. In respects ousness. Romneya is a shrub to 2.5 m, in other than these, it agrees with features com chaparral and coastal sage associations of Ca mon to woody Papaveraceae; these features lifornia and northern Baja California (Munz in turn occur in families of Papaverales (Ber 1974); the stems branch from the base, and beridaceae, Lardizabalaceae, Ranunculaceae): last only for several years each, so that wood vessels in diagonal groups; presence of both accumulation is less than in Dendromecon. libriform fibres and vasicentric tracheids; nu Hunnemannia, which occurs on the Mexican cleated nature of libriform fibres; rays almost Plateau, is a small to medium-sized shrub, exclusively multiseriate; rays wide, tall, and woody at the base (the specimen in the pres composed mostly of procumbent cells; wood ent study was collected in Hawaii, where it is storied to various degrees. Additional fea adventive). Much less woody is Dicentra tures show resemblance between one or more chrysantha. Although most species of Dicen genera of Papaveraceae and other families of tra are relatively herbaceous, the rhizomes Papaverales. Bocconia is distinctive among and lower stems of D. chrysantha and D. Papaveraceae in its relatively mesomorphic ochroleuca Engelm. are conspicuously stout wood, which may in part be explainable on and woody; upright innovations from these the basis of stem succulence. The occurrence rhizomes are woody at bases. Degree and are relevant to the study of a vessel restriction pattern — vessels in the kind of woodiness centre of fascicular areas (axial portions of of wood anatomy; Cumbie (1983), by study secondary xylem between rays) not in contact ing wood ontogeny of Bocconia vulcanica, believes Bocconia wood to exemplify pae with rays — in Dicentra and Hunnemannia is like that of other genera of Papaverales such domorphosis. Dendromecon is, as Cumbie as Nandina. An explanation for the signifi (1983) notes, probably not closely related to cance of vessel restriction, involving genera Bocconia, and therefore there is a possibility other than those of Papaverales (Launea, Va that it may be primarily rather than secondar leriana), is attempted. ily woody. This concept seems more plau Key words: Ecological wood anatomy, sys sible than the earlier phylogeny offered by tematic wood anatomy, vessel restriction Fedde (1936: 18, 58) in which he postulates patterns, Papaveraceae. a linear series leading from Corydalis to Eschscholzia to Dendromecon to Bocconia Introduction (and thence on to Glaucium and other herba Papaveraceae are not generally considered ceous genera). In addition to primary versus woody to any appreciable degree, although in secondary woodiness, degree of woodiness 254 IAWA Bulletin n.s., Vol. 9 (3), 1988 is a concern; for example, the stems studied ly attained consensus, despite the presence of Dendromecon rigida subsp. rhamnoides of quite different views in earlier literature. are much larger than those of D. rigida The treatment of Dahlgren (1980), Takhtajan subsp. rigida (Table 1, column 1). Likewise, (1987), and Thorne (1976) group together the differences between stem and root wood the families Papaveraceae (including Fuma in Dicentra offer interesting comparisons. riaceae in the present study), Berberidaceae, Papaveraceae that are essentially herbaceous, Circaeastraceae, Kingdoniaceae, Lardizabala with only very thin woody cylinders at bases ceae, Menispermaceae, Ranunculaceae, and at most (e.g., Argemone) have not been in Sargentodoxaceae (as well as such segregate cluded in the present study. families as Glaucidiaceae, Nandinaceae, and None of the Papaveraceae in the present Podophyllaceae). Recent data are at hand on study occur in wet forest habitats. Bocconia wood anatomy of some of these families, is a tree in shrubby montane forest; however, such as Lardizabalaceae (Cariquist 1984a) bark and pith succulence in Bocconia suggest and Ranunculaceae (Sieber & Kuëera 1980). the existence of features that modify xylary Wood anatomy of Papaveraceae can be com adaptation to dry conditions. The roots and pared with that of these other families in an stem bases of Dicentra chrysantha are also attempt to see to what degree wood anatomy succulent and rich in starch. Dendromecon reinforces the idea that the families named and Romneya are not at all succulent, and in form a natural grouping. these genera one may expect wood anatomy Little data have been accumulated on to reflect ecology more directly. wood anatomy of Papaveraceae. As the sum Although only a single species of Dendro mary of Fedde (1936) shows, most work on mecon is recognised here, in accordance with the anatomy of the family emphasised study the treatment of Munz (1974), that species of laticifers or leaf anatomy. Harvey-Gibson does possess considerable ecological ampli and Bradley (1917) commented only briefly tude. Dendromecon rigida subsp. rhamnoides on features of wood anatomy (e.g., helical occurs in the moderate climate of offshore is thickenings in tracheids of Romneya). The lands of California, whereas D. rigida subsp. brief account of wood of Papaveraceae con rigida can be found in summer-hot chaparral tains virtually all of what we know. Data on areas with less than 30 cm annual rainfall. Dendromecon and Romneya were provided The term ‘vessel restriction patterns’ has recently by Carlquist and Hoekman (1985). been applied to those instances in which ves sels are confined (to various degrees) to the Materials and Methods central portions of fascicular areas and do not Wood samples were available in dried contact ray cells. Attention was called to an form except for Dendromecon rigida subsp. instance in Valeriana (Cariquist 1988). The rigida and Dicentra chrysantha; portions of phenomenon has been illustrated in Launea these were preserved in formalin-acetic-alco (Asteraceae), and the term invented in that hol. Woods were sectioned on a sliding mi instance (Carlquist 1988). The occurrence of crotome except for Dicentra. Sections of vessel restriction in certain of the Papavera greater thickness (e.g., 30 .tm) were prepared ceae studied here has led to an assessment of for Bocconia and Hunnemannia in order to this phenomenon in terms of its occurrence minimise collapse of vessels in ransections. systematically and with respect to habit. The Thick sections were not disadvantageous be phenomenon of vessel restriction does not cause cell size is greater in these genera than seem related to the ‘isolation’ syndrome of in the other genera. For the stems and roots rays (e.g., the wide or aggregate rays in Fa of Dicentra chiysanrha, an alternative meth gaceae), which Braun (1970) described from od involving softening in ethylene diamine woody species quite unlike Papaveraceae in followed by sectioning portions in paraffin habit. on a rotary microtome (Carlquist 1982a) was The systematic affinities of Papaveraceae employed. Sections were stained in safranin; and the constitution of an order that may be formost collections, sections were also coun called Papaverales or Berberidales have near- terstained in fast green. Macerations were Cariquist & Zona — Wood anatomy of Papaveraceae 255 prepared with Jeffrey’s fluid and stained with Anatomical results safranin. Photographs utilising scanning elec tron microscopy (S EM) were derived from Growth rings sliding microtome sections with the use of an Growth rings are absent or nearly so in ISI WB-6 electron microscope. The mottled Bocconia (Fig. 1), Dicentra (Fig. 10), and appearance of SEM photographs presented Hunnemannia (Fig. 15). In contrast, Dendro here is not the result of charging; it repre mecon (Fig. 11) and Romneya (Fig. 16) are sents natural depositions on the vessel walls ring-porous to varying degrees. The ring po illustrated. rosity of these two genera takes the form of The means in Table 1 are based upon 25 larger vessels in earlywood; the larger vessels measurements per feature except for vessel tend to be in smaller groupings than the late- wall thickness, libriform fibre diameter at wood vessels, and vasicentric tracheids are widest point (as seen in transection), libri less abundant in earlywood than in latewood, form fibre wall thickness, and diameter of pits although they are present throughout growth on lateral walls of vessels. For these features, rings in Dendromecon and Romneya. means were derived from a few carefully se lected measurements. Vessel diameter was Quantitative vessel features taken at widest point within a vessel and is The number of vessels per group has been the lumen diameter. The presence of very computed in Table 1, column 2. A difference narrow vessels that are close to vasicentric between Bocconia (2.1 or fewer vessels per tracheids in diameter presented a problem, group: Fig. 1) and the other genera (3.6 or and some narrow vessels may have been in more vessels per group) is evident. Because advertently omitted from calculations. Ter very narrow vessels may have been missed minology follows the IAWA Committee on during measurements, the number of vessels Nomenclature (1964), except for vasicen per group in Dendromecon and Romneya tric tracheids, where the usage of Cariquist may be slightly higher than those recorded in (1985) and Carlquist and Hoekman (1985) is Table 1. The large groupings of vessels in followed; this usage is much like that of Met the latewood of Dendromecon (Fig.