Systematic and phylogenetic value of wood anatomy in Heteromorpheae (Apiaceae,Apioideae)

The wood anatomy of all four woody genera of the tribe Heteromorpheae (Apiaceae, subfamily Apioideae) has been described and compared, based on 40 wood samples (representing nine species of Anginon, one species of Glia, three species of Heteromorpha and two species of Polemannia). The four genera were found to be relatively similar in their wood anatomy. Helical thickenings on the vessel walls occur in all species investigated and appear to represent an ancestral character state and a symplesiomorphy for the tribes Bupleurieae and Heteromorpheae. Each of four genera has a diagnostically different combination of character states relating to the diameter of vessels, size of intervessel pits, length of fibres, presence and arrangement of banded axial parenchyma, size of rays and ray cells, and presence of septate fibres and crystals in the ray cells. The occurrence of marginal axial parenchyma in Anginon and Glia may be an additional synapomorphy for these taxa. Variation in the wood anatomy of 31 samples from nine species of Anginon is not correlated with habitat (Fynbos or Succulent Karoo Biomes), but instead appears to reflect adaptations to seasonal aridity found in both ecosystems. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 569–583.     

Caryophyllales: a key group for understanding wood anatomy character states and their evolution

Definitions of character states in woods are softer than generally assumed, and more complex for workers to interpret. Only by a constant effort to transcend the limitations of glossaries can a more than partial understanding of wood anatomy and its evolution be achieved. The need for such an effort is most evident in a major group with sufficient wood diversity to demonstrate numerous problems in wood anatomical features. Caryophyllales s.l., with approximately 12 000 species, are such a group. Paradoxically, Caryophyllales offer many more interpretive problems than other ‘typically woody’ eudicot clades of comparable size: a wider range of wood structural patterns is represented in the order. An account of character expression diversity is presented for major wood characters of Caryophyllales. These characters include successive cambia (more extensively represented in Caryophyllales than elsewhere in angiosperms); vessel element perforation plates (non‐bordered and bordered, with and without constrictions); lateral wall pitting of vessels (notably pseudoscalariform patterns); vesturing and sculpturing on vessel walls; grouping of vessels; nature of tracheids and fibre‐tracheids, storying in libriform fibres, types of axial parenchyma, ray anatomy and shifts in ray ontogeny; juvenilism in rays; raylessness; occurrence of idioblasts; occurrence of a new cell type (ancistrocladan cells); correlations of raylessness with scattered bundle occurrence and other anatomical discoveries newly described and/or understood through the use of scanning electron microscopy and light microscopy. This study goes beyond summarizing or reportage and attempts interpretations in terms of shifts in degrees of juvenilism, diversification in habit, ecological occupancy strategies (with special attention to succulence) and phylogenetic change. Phylogenetic change in wood anatomy is held to be best interpreted when accompanied by an understanding of wood ontogeny, species ecology, species habit and taxonomic context. Wood anatomy of Caryophyllales demonstrates problems inherent in binary character definitions, mapping of morphological characters onto DNA‐based trees and attempts to analyse wood structure without taking into account ecological and habital features. The difficulties of bridging wood anatomy with physiology and ecology are briefly reviewed. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 342–393.     

Asteropeia and Physena (Caryophyllales): A case study in comparative wood anatomy

Previous analyses ofAsteropeia andPhysena have not compared the wood anatomy of these genera to those of Caryophyllales s.l. Molecular evidence shows that the two genera from a clade that is a sister group of the core Caryophyllales. Synapomorphies of theAsteropeia-Physena clade include small circular alternate pits on vessels, presence of vasicentric tracheids plus fiber-tracheids, presence of abaxial-confluent plus diffuse axial parenchyma, and presence of predominantly uniseriate rays. These features are analyzed with respect to habit and ecology of the two genera. Solitary vessels, present in both genera, are related to the presence of vasicentric tracheids. Autapomorphies in the two genera seem related to adaptations byPhysena as a shrub of moderately dry habitats (e.g., narrower vessel elements, abundant vasicentric tracheids, square to erect cells in rays) as compared to alternate character expressions that seem related to the arboreal habit and humid forest ecology ofAsteropeia. The functional significance of vasicentric tracheids and fiber-tracheids in dicotyledons is briefly reviewed in the light of wood anatomy of the two genera.     

Living cells in wood. 1. Absence,scarcity and histology of axial parenchyma as keys to function

The diversity of expression in axial parenchyma (or lack of it) in woods is reviewed and synthesized with recent work in wood physiology, and questions and hypotheses relative to axial parenchyma anatomy are offered. Cell shape, location, abundance, size, wall characteristics and contents are all characteristics for the assessment of the physiological functions of axial parenchyma, a tissue that has been neglected in the consideration of how wood histology has evolved. Axial parenchyma occurrence should be considered with respect to mechanisms for the prevention and reversal of embolisms in tracheary elements. This mechanism complements cohesion–tension‐based water movement and root pressure as a way of maintaining flow in xylem. Septate fibres can substitute for axial parenchyma (‘axial parenchyma absent’) and account for water movement in xylem and for the supply of carbohydrate abundance underlying massive and sudden events of foliation, flowering and fruiting, as can fibre dimorphism and the co‐occurrence of septate fibres and axial parenchyma. Rayless woods may or may not contain axial parenchyma and are informative when analysing parenchyma function. Interconnections between ray and axial parenchyma are common, and so axial and radial parenchyma must be considered as complementary parts of a network, with distinctive but interactive functions. Upright ray cells and more numerous rays per millimetre enhance interconnection and are more often found in woods that contain tracheids. Vesselless woods in both gymnosperms and angiosperms have axial parenchyma, the distribution of which suggests a function in osmotic water shifting. Water and photosynthate storage in axial parenchyma may be associated with seasonal changes and with succulent or subsucculent modes of construction. Apotracheal axial parenchyma distribution often demonstrates storage functions that can be read independently of osmotic water shifting capabilities. Axial parenchyma may serve to both enhance mechanical strength or, when parenchyma is thin‐walled, as a tissue that adapts to volume change with a change in water content. Other functions of axial parenchyma (contributing resistance to pathogens; a site for the recovery of physical damage) are considered. The diagnostic features of axial parenchyma and septate fibres are reviewed in order to clarify distinctions and to aid in cell type identification. Systematic listings are given for particular axial parenchyma conditions (e.g. axial parenchyma ‘absent’ with septate fibres substituting). A knowledge of the axial parenchyma information presented here is desirable for a full understanding of xylem function. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 291–321.     

Comparative palynology and wood anatomy of <Emphasis Type="Italic">Taxodium distichum</Emphasis> (L.) Rich. and <Emphasis Type="Italic">Taxodium mucronatum</Emphasis> Ten.

A comparative study of Taxodium distichum (L.) Rich. and Taxodium mucronatum Ten. was carried out on the basis of pollen morphology and wood anatomy by light and scanning electron microscopy. We describe a detailed analysis of the anatomical characteristics of the wood, including the tracheids, ray parenchyma, axial parenchyma and number of cross-field pits. Palynological characters were also studied to reveal the shape, size and ultrastructure of the pollen grains. These studies give taxonomic support for the recognition of T. distichum and T. mucronatum as two different species.     

Comparative wood anatomy in Abietoideae (Pinaceae)

This study, which includes 51 species and six genera of subfamily Abietoideae (Pinaceae), assesses the systematic significance of the wood structure in this group. In particular, the presence of normal and traumatic resin canals, the ray structure and the axial parenchyma constitute phylogenetically informative features. Comparative wood anatomy of Abietoideae clearly supports the monophyly of the genera Abies–Cedrus–Keteleeria–Nothotsuga–Pseudolarix–Tsuga, all of which have axial parenchyma with nodular transverse end walls in the regions of growth ring boundaries, crystals in the ray parenchyma and pitted horizontal and nodular end walls of ray parenchyma cells. Axial resin canals support a subdivision of the subfamily into two groups: Abies, Cedrus, Pseudolarix and Tsuga, without axial resin canals, and Keteleeria and Nothotsuga, with axial resin canals and a specific arrangement of traumatic axial resin canals. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 184–196.     

Comparative wood anatomy ofCoriaria

Wood anatomy ofCoriaria was surveyed to clarify generic features on the basis of 14 species collected from various regions of the World to cover the whole range of geographic distribution and habitual variation. Wood anatomy ofcoriaria is considerably uniform, and the species share a combination of the following features: 1) pores are thin-walled, polygonal in outline and mostly in multiples; 2) vessel elements and libriform fibers are very short; 3) perforation plates are exclusively simple; 4) intervessel pits are alternate; 5) vascular tracheids are present; 6) wood parenchyma is vasicentric and sometimes confluent; 7) rays are heterogeneous and large. Its species differ in several characters, such as distinctness of growth rings, pore size, pore patterns, type and abundance of wood parenchyma, and distinctness of storied structure. Comparisons among species indicate that the species of the Northern Hemisphere show a tendency toward having semi-ring porosity, while those of the Southern and Western Hemisphere have diffuse porosity. The other infrageneric variations appear to be related to different habits of the species rather than to geographic distribution. Small trees mostly have confluent and vasicentric parenchyma composed of fusiform cells and distinctly storied tissues, while shrubs and herbs have less abundant parenchyma which is vasicentric and comprises strands of two to four cells and indistinctly storied tissues.     

Wood anatomy of theSarraceniaceae; ecological and evolutionary implications

The wood of theSarraceniaceae has a considerable number of primitive features including scalariform perforation plates, long and oblique end walls, scalariform lateral wall pitting, solitary vessels, tracheids with scalariform pitting, and diffuse axial parenchyma. Vessel elements in the genusHeliamphora have the greatest number of primitive features, while vessel elements inDarlingtonia andSarracenia appear to have modifications relating to temperate climates. The wood anatomy suggests thatHeliamphora is growing in a habitat more similar to the original habitat for the family thanDarlingtonia andSarracenia. The wood of theSarraceniaceae is similar to the wood of theTheales.     

Systematic and ecological wood anatomy of Neotropical Schefflera (Araliaceae), with an emphasis on the Didymopanax group

Wood anatomy has been investigated from 35 species belonging to the Neotropical clade of the polyphyletic genus Schefflera (Araliaceae), representing three of the five subgroups (Didymopanax, Crepinella and Sciodaphyllum). The species examined are rather uniform in their wood structure, sharing the presence of scalariform and simple perforation plates, septate fibres and scanty paratracheal axial parenchyma. The observed variation in many wood characters showed statistically significant differences relative to latitude, climate and, especially, vegetation types. In particular, the intervessel pits are larger in species from higher latitudes and in seasonally dry habitats than those from lower latitudes and rainforests. Latitudinal and ecological trends in the variation of vessel element lengths, bar numbers on perforation plates, intervessel pit sizes and ray widths may be at least partially explained as effects of adaptation to drier environments in the course of dispersal outside the Amazonian region and diversification in the Atlantic Forest subclade and the Savannic subclade within the Didymopanax group. The occurrence of a granular annulus on the intervessel pit membranes in S. chimantensis and S. sprucei (both of the Crepinella group) is the first record of this feature in Araliaceae. In comparisons of Neotropical Schefflera with the other major clades of Schefflera sensu lato, wood anatomical diversity is consistent with the polyphyly of this genus based on molecular phylogenetic analyses. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 452–475.     

Wood anatomy of daphniphylla ceae: Ecological and phylogenetic considerations,review of pittosporalean families

Wood anatomy of 16 collections representing three species containing eight subspecies of the single genusDaphniphyllum is analyzed quantitatively and qualitatively.Daphniphyllum has vessels angular to roundish in transection, scalariform perforation plates, scalariform to opposite lateral wall vessel pitting, tracheids with fully bordered pits, heterocellular multiseriate and uniseriate rays, diffuse axial parenchyma and, in one taxon, chambered crystals in axial parenchyma cells. Growth rings, narrower vessels, and more numerous, vessels per square mm characterize taxa from cooler habitats. All of the taxa have highly mesomorphic woods. Comparisons are made between Daphniphyllaceae and the other families of Thorne's Pittosporales (Balanopaceae, Bruniaceae, Buxaceae, Byblidaceae, Geissolomataceae. Grubbiaceae, Myrothamnaceae, Pittosporaceae, Roridulaceae, and Tremandraceae). These families are most comparable to hamamelidoid or rosoid families; other similarities or relationships for these families may exist, but are less conspicuous or less close. The families cited may form a plexus, characterized by primitive xylary and other features, comparable to Annonales (Magnoliales) as products of an early radiation of dicotyledons.     

Contributions to the Wood Anatomy of the Rubioideae (Rubiaceae)

Damnacanthus , Lasianthus, Saldinia, and Trichostachys are also included. Wood anatomical characters are compared with recent phylogenetic insights into the study group on the basis of molecular data. The observations demonstrate that the delimitation and separation of several taxa from the former Coussareeae/Morindeae/Prismatomerideae/Psychotrieae aggregate is supported by wood anatomical data. The Coussareeae can be distinguished from the other Rubioideae by their scanty parenchyma, septate libriform fibres, and the combination of uniseriate and very high multiseriate rays with sheath cells. Axial parenchyma bands and fibre-tracheids characterise Gynochtodes and some species of Morinda (Morindeae s.str.), but the latter genus is variable with respect to several features (e.g. vessel groupings and axial parenchyma distribution). Wood data support separation of Rennellia and Prismatomeris from Morindeae s.str.; vessels in both genera are exclusively solitary and axial parenchyma is always diffuse to diffuse-in-aggregates. Damnacanthus differs from the Morindeae alliance by the occurrence of septate fibres, absence of axial parenchyma, and the occasional presence of fibre wall thickenings. There are interesting similarities between members of the Lasianthus clade and the Pauridiantheae/Urophyleae group such as the sporadic occurrence of spiral thickenings in axial parenchyma cells. Received 26 January 2001/ Accepted in revised form 6 June 2001     

Annual tree rings revealed by radiocarbon dating in seasonally flooded forest of the Mapire River,a tributary of the lower Orinoco River,Venezuela

The occurrence of seasonal growth rings in the wood of Campsiandra laurifolia, Acosmiun nitens, Pouteria orinocoensis and Psidium ovatifolium, common species growing in the flooding forest of the Mapire river, was analyzed using wood anatomy and ring- width analysis. The test of the annual ring formation was performed using radiocarbon analysis based on the nuclear weapon effect. All species showed growth rings visible to the naked eye. The ring boundaries in all cases were marked by bands of marginal parenchyma. The index ring-width curves of the four studied species showed a strong relationship with the fluctuation of the water river level during the non flooded months, suggesting that an increase in the water level during these months positively influenced the growth indicating that the rings were formed on an annual basis. The content of radiocarbon in the wood of anatomically predated rings of Campsiandra laurifolia and Pouteria orinocoensis confirm these results. All studied trees are slow growing with less than 2.5 mm annual increment.     

Seasonal dimorphism in wood anatomy of the Mediterranean Cistus incanus L. subsp. incanus

In Mediterranean-type ecosystems, seasonal dimorphism is an adaptive strategy aimed to save water by developing brachyblasts with xeromorphic summer leaves as opposed to dolichoblasts with more mesomorphic winter leaves. The aim of this study was to analyse the anatomical properties of 1-year-old twigs of Cistus incanus subsp. incanus, a seasonally dimorphic shrub, to highlight properties allowing its adaptation to the Mediterranean environment. A more specific purpose was to verify the occurrence of seasonal dimorphism in wood anatomy in order to understand: (a) whether and to what extent the traits of efficiency/safety of water transport are expressed in brachyblasts and dolichoblasts, and (b) the effects on the formation of growth ring boundaries in wood. Our overall analysis showed that anatomical features of branches in C. incanus are designed to: (a) protect from desiccation by developing thick cuticle and suberized epidermal and sub-epidermal layers; (b) defend the plant from predators by accumulating phenolics; and (c) regulate water transport through the development of specific wood anatomy, according to the season, thus optimising properties of efficiency/safety. Regarding the latter point, our results indicated that brachyblast wood is safer than dolichoblast wood insofar as it has narrower and more frequent vessels; measurement of other specific anatomical traits, such as vessel wall thickness, suggested that brachyblast wood has a higher resistance to implosion due to drought-induced embolism. Finally, peculiar anatomy of brachyblast and dolichoblast wood results in the formation of so-called false rings. Hence, wood rings in C. incanus should be considered to be “seasonal” rather than “annual”.     

Wood and bark anatomy of Steganotaenia and Polemanniopsis (tribe Steganotaenieae,Apiaceae) with notes on phylogenetic implications

The wood and bark structure of the distinctive southern African genera Polemanniopsis (including the newly described species P. namibensis) and Steganotaenia have been described. To allow for comparisons with the traditional subfamily Saniculoideae, a shrubby species of Eryngium from the Juan Fernández Islands was also studied. Polemanniopsis and Steganotaenia were recently considered as two closely related genera forming a new tribe Steganotaenieae of subfamily Saniculoideae (Apiaceae), whereas Eryngium is commonly recognized as a member of Saniculoideae. Eryngium differs significantly from the other two genera in the smaller size of intervessel pits, sclerification and radial dilatation in collapsed secondary phloem, the absence of crystals in the phelloderm cells and the occurrence of druse crystals in secondary phloem ray cells. Steganotaenia and Polemanniopsis share features, including the presence of marginal axial parenchyma, the occurrence of radial secretory canals in secondary xylem, dilatation of the secondary phloem by axial parenchyma stretching, cortical periderm initiation and the presence of chambered phelloderm cells containing druse crystals. These characters (especially the occurrence of chambered crystalliferous cells in phelloderm, which has not yet been reported for Apiaceae) support both the monophyly and the isolated position of the Steganotaeniae. No reliable synapomorphic features could be found to support a relationship with Saniculoideae. Steganotaenia is remarkable in the presence of axial secretory canals in the phelloderm: these structures have not yet been found in the periderm of any member of Apiales. Our results do not provide any support for the suggestion that the woody habit in the three genera examined was derived from herbaceous ancestors secondarily. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 55–59.     

The function of intercellular spaces along the ray parenchyma in sapwood, intermediate wood, and heartwood of Cryptomeria japonica (Cupressaceae)

? Premise of the study: Intercellular spaces along ray parenchyma (ISRP) are common in many conifer xylems, but their function is uncertain because the in-situ structural network among ISRP, ray parenchyma, and tracheids has not been evaluated. Analysis of water distribution in ISRP from sapwood to heartwood is needed to elucidate the function of ISRP in sapwood, intermediate wood, and heartwood. ? Methods: We used cryo-scanning electron microscopy, x-ray photography, and water content measurement in xylem to analyze the presence of liquids in ISRP, ray parenchyma, and tracheids from sapwood to heartwood in Cryptomeria japonica (Cupressaceae). ? Key results: In sapwood, almost all ISRP were empty. "Cingulate-cavitated regions", which lose water along the tangential direction within one annual ring, formed in the earlywood tracheids, and their frequency increased toward the inner annual rings, whereas ray parenchyma cells were alive and not involved in the partial cavitation. In intermediate wood, almost all ISRP and earlywood tracheids and many of the ray cells were empty, and only some latewood tracheids retained liquid in their lumina. The ISRP were connected with tracheids via gas-filled ray parenchyma cells. ? Conclusions: The ISRP work as a pathway of gas for aspiration of ray parenchyma cells in sapwood. On the other hand, the occurrence of a gas network between ISRP, ray parenchyma, and tracheids facilitates cavitation of tracheids, resulting in the generation of low-moisture, intermediate wood.     

Stem and root anatomical correlations with life form diversity, ecology, and systematics in Moringa (Moringaceae)

Four life forms (habits) are identified in the 13 species of Moringa (bottle trees, sarcorhizal trees, slender trees, and tuberous shrubs) which are examined for wood anatomical correlations with habit, ecology, and systematic. Wood anatomy is similar within habit classes except for the sarcorhizal trees. The four bottle tree species and M. arborea (one of the sarcorhizal trees) are characterized by bands of confluent paratracheal parenchyma alternating with bands of libriform fibres, some of which may be parenchyma-like. The other sarcorhizal tree, M. ruspoliana , is characterized by alternating bands of parenchyma-like and long, slender libriform fibres. Root secondary xylem of all these species is characterized by bands of parenchyma and fibres. Slender trees do not show bands of fibres of different shapes and have fibrous roots with less parenchyma than the other species. Tuberous shrubs have stems mostly composed of long, slender fibres and large underground tubers mostly composed of parenchyma. Quantitative trends between ecologically different localities include wider vessel elements and higher conductive area in moister localities. Wood anatomy provides characters that are of potential phylogenetic utility at a variety of levels of relationship. Based on wood anatomy and geography, the most likely sister taxon to Moringa is Cylicomorpha (Caricaceae).     

Living Cells in Wood 3. Overview; Functional Anatomy of the Parenchyma Network

The very different evolutionary pathways of conifers and angiosperms are very informative precisely because their wood anatomy is so different. New information from anatomy, comparative wood physiology, and comparative ultrastructure can be combined to provide evidence for the role of axial and ray parenchyma in the two groups. Gnetales, which are essentially conifers with vessels, have evolved parallel to angiosperms and show us the value of multiseriate rays and axial parenchyma in a vessel-bearing wood. Gnetales also force us to re-examine optimum anatomical solutions to conduction in vesselless gymnosperms. Axial parenchyma in vessel-bearing woods has diversified to take prominent roles in storage of water and carbohydrates as well as maintenance of conduction in vessels. Axial parenchyma, along with other modifications, has superseded scalariform perforation plates as a safety mechanism and permitted angiosperms to succeed in more seasonal habitats. This diversification has required connection to rays, which have concomitantly become larger and more diverse, acting as pathways for photosynthate passage and storage. Modes of growth such as rapid flushing, vernal leafing-out, drought deciduousness and support of large leaf surfaces become possible, advantaging angiosperms over conifers in various ways. Prominent tracheid-ray pitting (conifers) and axial parenchyma/ray pitting to vessels (angiosperms) are evidence of release of photosynthates into conductive cells; in angiosperms, this system has permitted vessels to survive hydrologic stresses and function in more seasonal habitats. Flow in ray and axial parenchyma cells, suggested by greater length/width ratios of component cells, is confirmed by pitting on end walls of elongate cells: pits are greater in area, more densely placed, and are often bordered. Bordered pit areas and densities on living cells, like those on tracheids and vessels, represent maximal contact areas between cells while minimizing loss of wall strength. Storage cells in rays can be distinguished from flow cells by size and shape, by fewer and smaller pits and by contents. By lacking secondary walls, the entire surfaces of phloem ray and axial phloem parenchyma become conducting areas across which sugars can be translocated. The intercontinuous network of axial parenchyma and ray parenchyma in woods is confirmed; there are no “isolated” living cells in wood when three-dimensional studies are made. Water storage in living cells is reported anatomically and also in the form of percentile quantitative data which reveal degrees and kinds of succulence in angiosperm woods, and norms for “typically woody” species. The diversity in angiosperm axial and ray parenchyma is presented as a series of probable optimal solutions to diverse types of ecology, growth form, and physiology. The numerous homoplasies in these anatomical modes are seen as the informative results of natural experiments and should be considered as evidence along with experimental evidence. Elliptical shape of rays seems governed by mechanical considerations; unusually long (vertically) rays represent a tradeoff in favor of flexibility versus strength. Protracted juvenilism (paedomorphosis) features redirection of flow from horizontal to vertical by means of rays composed predominantly or wholly of upright cells, and the reasons for this anatomical strategy are sought. Protracted juvenilism, still little appreciated, occurs in a sizeable proportion of the world’s plants and is a major source of angiosperm diversification.     

Wood and bark anatomy of lianoid Indomalesian and Asiatic species of Gnetum

Quantitative and qualitative data on wood and bark are offered for 11 species of lianoid Indomalesian and Asiatic species of Gnetum section Cylindrostachys. Material of roots was studied for two species, material of an underground stem for one species, and stem material was studied for all species; wood from inside and outside of a large stem of G. montanum was analysed (quantitative data do not change with age in this species). Roots have shorter, narrower vessel elements, more numerous per mm², compared with those of stems; these trends run counter to those in dicotyledons. Roots and underground stems have more abundant parenchyma and less abundant sclerenchyma than do stems. Parenchyma of both roots and stems is rich in starch. All of the species studied here have both fibre-tracheids and tracheids, but tracheids are not distributed vasicentrically as they are in dicotyledons. Tori are reported for tracheary elements of three species studied here. Vasicentric axial parenchyma (which usually is thick-walled) is present in all species; thick or thin-walled diffuse or diffuse-in-aggregates apotracheal parenchyma is present in almost all of the species studied. Rays are mostly dimorphic in size, but show various conditions with respect to wall thickness, sclerenchyma presence, and crystal presence. As in other lianoid species of Gnetum, the species of the present study show origin of lateral meristem activity in parenchyma of the innermost cortex. Cortex and bark of the species studied here are relatively uniform in distribution of gelatinous fibres, nests of sclereids, the cylinder of brachysclereids that extends around the stem, and sclerenchymatous phelloderm. Laticifers were observed in bark of only two species studied. Although a few species characters are evident, the species that comprise Section cylindrostachys differ from each other mostly in degree rather than in presence or absence character state distributions. Secretory cavities are newly reported for the genus.     

广义锦葵科火绳树属4个种的枝条木材解剖及其分类学意义

研究了广义锦葵科火绳树属4个种枝条的木材解剖。火绳树属枝条为散孔至半环孔材,管孔主要为单管孔和2～3个管孔组成的径列复管孔;导管间纹孔式和射线导管间纹孔式互列、小;侵填体和螺纹加厚缺如。射线主要为单列射线,2～3列射线较多;射线细胞多为方形,射线组织主要为异型,边缘直立细胞常1行;射线组织稀为同型;鞘细胞和瓦形细胞缺如。轴向薄壁组织傍管和离管型,主要为带状。晶体丰富,主要在射线、纤维和薄壁组织中。研究的4个种可以通过枝条木材解剖特征加以区分。