PATTERNS OF ENDOTHECIAL WALL THICKENINGS IN ARACEAE: SUBFAMILIES POTHOIDEAE AND MONSTEROIDEAE

A survey of the patterns of endothecial wall thickenings in 106 representative species from 20 genera in the Pothoideae and Monsteroideae was made using cleared anthers, sections and macerations. The wide variety of wall thickenings that is present is based on an annular-helical pattern. Variations in thickenings are related to differences in cell shape, cell orientation, intergradation between helical and annular patterns, pitch of helices, presence of branched thickenings, and various types of discontinuities in thickenings. Notable exceptions to the annular-helical pattern include Culcasia, which lacks a differentiated endothecial layer with thickenings, and Acorus, which has a peculiar stellate pattern that is unique in the family. No single pattern consistently characterizes either subfamily, although continuous helices are common in the Monsteroideae, and rare in the endothecium of Pothoideae (except Anadendrum). Monsteroideae frequently exhibit a series of slanted separate thickenings on anticlinal walls, which is absent from Pothoideae except in Heteropsis. The slanted pattern is considered a variation on a rectangular helix, involving discontinuities of thickenings on the periclinal walls. Some monsteroid genera show considerably more interspecific variation (Rhaphidophora) than others (Monstera). Endothecial thickenings constitute an anatomical character that is useful in the systematic study of Araceae; present results support other anatomical studies in identifying Culcasia and Acorus as highly divergent genera in the Pothoideae.     

VASCULAR PATTERNS IN STEMS OF ARACEAE: SUBFAMILY MONSTEROIDEAE

Analysis of stem vasculature in representatives of subfamily Monsteroideae (Araceae) by cinematographic techniques based on serial sections shows three main patterns of organization. One group of five genera (Rhaphidophora, Epipremnum, Amydrium, Scindapsus, Monstera) is characterized by simple vascular bundles and axial bundles which are derived by basal aggregation of small bundles branching from existing axial bundles. Another group of two genera (Stenospermation, Rhodospatha) is characterized by compound vascular bundles which are made by rather irregular association of individual collateral bundles. These two groups correspond to the tribe Monstereae. The last group which corresponds to the tribe Spathiphylleae includes two genera (Spathiphyllum, Holochlamys) with amphivasal vascular bundles which are highly condensed and irregularly anastomosing. In part, this division is correlated with habit and habitat. Some members of the first group resemble genera within the subfamily Pothoideae quite closely and indicate that the two subfamilies are not clearly circumscribed. Compound bundles in Rhodospatha and Stenospermation do not have the precise organization previously reported for the Pandanaceae.     

PATTERNS OF STAMEN VASCULATURE IN THE ARACEAE

A survey of the three-dimensional organization of stamen vasculature in 100 genera and over 350 species of Araceae was made using clearings. The Araceae exhibit highly varied stamen vasculature, with three main patterns: 1) vascular bundles unbranched, 1–3 per stamen, 2) forked bundles in some or all stamens, 3) anastomosing vascular systems with several to many bundles entering a single stamen. Three major groups of taxa in the family can be recognized on the basis of their predominant pattern of stamen vasculature. Virtually all genera with bisexual flowers (most Pothoideae, Monsteroideae, Calloideae, Lasieae) have unbranched bundles, one per stamen, except two to three in some species of Holochlamys, Spathiphyllum, and Scindapsus. Forked stamen bundles are virtually restricted to and occur nearly throughout the monoecious Lasioideae, Philodendroideae, Colocasioideae and among certain Aroideae (sensu Engler), including tribes Arophyteae, Spathicarpeae (Asterostigmateae) and Protareae. No forked bundles were found in tribe Areae (Aroideae), except Theriophonum indicum or any Araceae with bisexual flowers, except two species of Cyrtosperma. Anastomosing systems are virtually limited to members of tribe Areae with larger stamens, such as Arum, Helicodiceros, Eminium and Dracunculus species. A similar pattern occurs in some Amorphophallus, but other patterns occur as well. The distributions of forked bundles and anastomosing systems in the family are notable because they are both highly congruent with Philodendroideae-Colocasioideae, and Aroideae, respectively, in Grayum's new system for the family. Virtually all of the genera with forked bundles are grouped together in the Philodendroideae-Colocasioideae. All of the genera with anastomosing systems are in the Areae, including the complex and variable Amorphophallus, which has an uncertain systematic placement.     

VASCULAR PATTERNS IN STEMS OF ARACEAE: SUBFAMILY POTHOIDEAE

The stem vasculature of representative species of ten of the 11 genera in the Pothoideae was analyzed with the aid of films of series of transverse sections. In all species a leaf trace typically diverges from a continuing axial bundle before departing to a leaf, with the possible exception of Heteropsis. However, within this common organizational scheme a considerable range of variation exists, e.g., with respect to degree of branching of axial bundles, and distance from a leaf-trace branch to the point of leaf-trace departure to a leaf. In addition, we have found a wide variety of patterns of bud-trace organization in different genera of the Pothoideae. For example, prominent arcs composed of numerous bud traces occur in the central cylinder of Pothos, Pothoidium, and Heteropsis. Comparative anatomy leads to the conclusion that Pothos and Pothoidium more closely resemble Heteropsis than Anadendrum. Anadendrum should be dissociated from the tribe Pothoeae. With respect to other genera in the Pothoideae, our preliminary results suggest that each of the genera Anthurium, Culcasia, Zamioculcas, Acorus, and Gymnostuchys are highly distinct from each other.     

The leaf development process and its significance for reducing self-shading of a tropical pioneer tree species

On a monoaxial erect stem of trees with continuous leafing, the older leaves would be quickly shaded by newer (upper) leaves if the trees did not have any compensating mechanisms to avoid self-shading. We hypothesized that the dynamic adjustment of leaf deployment, by regulating the patterns of leaf growth and by changing leaf orientation as leaves age, is a compensating mechanism. To verify this hypothesis, we analyzed leaf development and crown structure of a Far Eastern tropical pioneer tree species, Macaranga gigantea (Rub. f. et Toll.) M.A., which unfolds huge leaves directly on a monoaxial stem with a short leafing interval. Petioles required more than 90 days for full elongation and the petiole angle (the angle between the petiole axis and the vertical) increased over time. Thus, a series of leaves on a stem progressively increased in petiole length and petiole angle from the youngest to the oldest leaves. This is beneficial because it decreases the degree of self-shading within a crown. A simulation suggested that an average crown for the M. gigantea seedlings, which was constructed using empirically determined morphometric data cannot entirely eliminate self-shading within the crown. But an average crown had a lower degree of self-shading, with less dry mass allocation to the petiole than simulated crowns that were identical to the average crown in all but one respect: they had constant petiole lengths or petiole angles. We conclude that M. gigantea seedlings reduce self-shading by regulating elongation of the petiole and changes in the petiole angle with increasing leaf age.     

Phytophthora-Stammbasisfäule an Dieffenbachia maculate (Erreger: P. mexicana Hots. et Hart.)

Stem base rot of Dieffenbachia maculata caused by Phytophthora mexicana During the last years a stem rot of Dieffenbachia maculata (Lodd.) G. Don has been observed in greenhouses of several commercial nurseries, located in different parts of the Federal Republic of Germany. The disease partly caused heavy losses. From all diseased plant parts (stem base, petiole and root) the same fungus could be isolated. It was diagnosed as Phytophthora mexicana Hots, et Hart., which is closely related to P. palmivora (Butl.) Butl. Apparently the former species is recorded for the first time as the causal organism of a Dieffenbachia stem rot and also for the first time in Europe. It is supposed that the fungus was imported to Germany via the Netherlands because all plants had been bought there, which diseased later.     

STUDIES OF PALEOZOIC FERNS: THE FROND OF ANKYROPTERIS GLABRA

Eggert , Donald A. (Southern Illinois U., Carbondale.) Studies of Palerzoic ferns: The frond of Ankyropteris glabra. Amer. Jour. Bot. 50(4): 379–387. Illus. 1963—The major features of the frond of A. glabra are described on the basis of preserved parts found in Middle Pennsylvanian coal ball material from Illinois. The frond is planated and has well-developed foliar laminae. Primary pinnae arise from the petiole in 2 alternating series, and secondary pinnae arise in a similar fashion from the primary pinnae. Foliar laminae occur on the secondary pinnae and have dichotomous venation. The xylem of the petiole has a diupsilon configuration in the lower part of the axis, while higher in the petiole the xylem forms a strand resembling that of the European species A. westfaliensis. The xylem strands of the primary pinnae arise from the adaxial antennae of the petiolar vascular strand as somewhat C-shapcd bodies and develop antennae and become H-shaped at higher levels. A gap occurs in the antenna of the petiole vascular system above the level of departure of the primary pinna trace. Terete vascular strands occur in the secondary pinna axes which arise from the adaxial antennae of the xylem of the primary pinnae. The foliar laminae are relatively thin, have an irregular outline, and their histology is like that found in many living ferns. The frond of A. glabra illustrates that leaf evolution had progressed in at least one species of the coenopterid family Zygopteridaceae to the extent that an essentially 2-dimensional frond of modern aspect, and with well-developed foliar laminae, was present by Middle Pennsylvanian time.     

Anatomical characterization of Strobilanthes (Acanthaceae) species from the northern Western Ghats of India and its implication for identification at vegetative state

A comprehensive study of stem, leaf and petiole anatomy of 10 species of Strobilanthes from northern Western Ghats of India was carried out to identify characteristics which would enable species identification when flowering material is unavailable. In Strobilanthes, some species bloom annually, others are plietesials, i.e. they grow without blooming for several years and then produce huge quantities of flowers, release seeds and die. Therefore, alternative methods, such as anatomical characters, are essential to distinguish Strobilanthes species in their vegetative stage. We collected ten species of Strobilanthes for anatomical characterization. Under the bright‐field microscope, stem cross‐sections of different species were found to be undulate, quadrangular, quadrangular‐winged or terete. Study of the stem revealed a distinct outer and inner cortex, the distribution of cystoliths (CaCO₃ crystals), raphides (CaC₂H₂O₅ crystals) and sclereids which varied from species to species. Study of leaf anatomy showed structural variation and vascular bundle shapes that differed between the species. Leaf epidermal characters under light and scanning electron microscopy exhibited variation in characters such as stomatal index, stomatal length and width, stomatal type and presence of glandular and non‐glandular trichomes. The petiole anatomy was species‐specific, especially with respect to vascular bundle structure and the distribution of structures such as sclereids, cystoliths, sphaeraphides and tannin cells varied. Hence, unique anatomical features of the stem, leaf and petiole could be used as taxonomic characters to identify Strobilanthes species in a vegetative state.     

Assessment of diversity,distribution and antibacterial activity of endophytic fungi isolated from a medicinal plant <Emphasis Type="Italic">Adenocalymma alliaceum</Emphasis> Miers

A study was conducted for isolation, identification and antibacterial potential of fungal endophytes of Adenocalymma alliaceum Miers., (Bignoniaceae), a medicinal shrub vine plant which has long history for its usages in curing various disorders. A total of 149 isolates of endophytic fungi representing 17 fungal taxa were obtained from 270 segments (90 from each stem, leaf and petiole) of this plant. Hyphomycetes (77.85%) were the most prevalent, followed by Ascomycetes (8.05%) and Coelomycetes (4.03%) respectively. A considerable amount of fungal isolates was kept under (10.07%) Mycelia-Sterilia (MS). Leaf harboured maximum colonization of endophytic fungi (72.22%) which was greater than stem (67.78%) and petiole (25.54%). The Jc similarity index was maximum (0.619) between stem vs leaf followed by leaf vs petiole (0.571) and stem vs petiole (0.428). The dominant endophytic fungi were Alternaria alternata, Aspergillus niger, Stenella agalis, Fusarium oxysporum, Curvularia lunata and Fusarium roseum. Among twelve endophytic fungi tested for antibacterial activity, crude extracts of nine endophytic fungi (75%), showed antibacterial potential against one or more clinical human pathogens. Alternaria alternata, Curvularia lunata, Penicillium sp. and Chaetomium globosum exhibited significant antibacterial activity against 4 of 5 tested pathogens, showing broad spectrum activity. This investigation explains the value of sampling from different tissues of a host plant for the greater species diversity, and additionally, the antibacterial screening of some endophytic fungi from this specific medicinal plant may represent a unique source for many of the useful antibacterial compounds.     

ANACHOROPTÉRIS INVOLUTA AND ITS ATTACHMENT TO A TUBICAULIS TYPE OF STEM FROM THE PENNSYLVANIAN OF IOWA

Hall , John W. (U. Minnesota, Minneapolis.) Anachoropteris involuta and its attachment to a Tubicaulis type of stem from the Pennsylvanian of Iowa. Amer. Jour. Bot. 48(8): 731–737. Illus. 1961.—Petioles referable to Anachoropteris involuta are described, attached to a stem which most nearly corresponds to a member of the genus Tubicaulis. These petioles are attached in a 2/5 phyllotaxy. At their points of departure petiole traces are massive and C-shaped but become involute in regions away from their attachment. Adventitious roots were borne on the stem in partial whorls. It is suggested that Anachoropteris petioles were extremely long and that they bore adventitious stems at intervals. These, in turn, bore adventitious roots, perhaps to serve for uptake of minerals or support in regions removed from the true stem. Such a “petiole unit” may also have functioned as a vegetative propagule. This would account for the apparent rarity of true stems and the abundance of petioles in coal balls.     

P-type sieve-element plastids and the systematics of theArales (sensuCronquist 1988)—with S-type plastids inPistia

The sieve-element plastids of 126 species of theArales were investigated by transmission electron microscopy. With the exception ofPistia (with S-type plastids) all contained the monocotyledon specific subtype-P2 plastids characterized by cuneate protein crystals. While the species studied from bothAcoraceae andLemnaceae have form-P2c plastids (i.e., with cuneate crystals only), those of theAraceae belong to either form P2c (14 species), P2cs (the great majority) or P2cfs (Monstera deliciosa, only, with form-P2cs plastids in the otherMonstera species studied). The form-P2cs plastids of theAraceae are grouped into different categories according to the quantity and quality of their protein and starch contents. The subfamilyLasioideae is redefined to comprise all aroid P2c-taxa and those P2cs-genera that contain only one or very few starch grains. Only little starch is also recorded in the sieve-element plastids ofGymnostachys (Gymnostachydoideae), with the other plastid data denying a close relationship toAcorus. While equal amounts of starch and protein are generally present in sieve-element plastids of the subfamiliesPothoideae, Monsteroideae, Colocasioideae, Philodendroideae, andAroideae, maximum starch content and only very few protein crystals are found in form-P2cs plastids ofCalla (Calloideae),Ariopsis (Aroideae), andRemusatia (Colocasioideae?). In the latter, both morphology and size of sieve-element plastids are close to those ofPistia.—In theAraceae the diameters of the sieve-element plastids exhibit a great size range, but are consistent within a species and within a defined part of the plant body. Comparative data are mainly available for stem and petiole sieve-element plastids.—The accumulated data are used to suggest an affiliation of the species to subfamilies and to discuss the phylogeny of theArales. Forms and sizes of their plastids support a separation of bothAcoraceae andLemnaceae from theAraceae. The presence of S-type plastids inPistia does not favour direct and close relationships to the form-P2c genusLemna.—The prevailing form-P2cs plastids might support proposals that place theArales (together with also form-P2cs plastid containingDioscoreales) in the neighbourhood of basal dicotyledons. BesidesAsarum andSaruma (Aristolochiaceae), with monocotyledonous form-P2c plastids,Pistia (with dicotyledonous S-type plastids) gives another example for a link between the two angiosperm classes.     

AUREALCAULIS CROSSII GEN. ET SP. NOV., AN ARBORESCENT,OSMUNDACEOUS TRUNK FROM THE FORT UNION FORMATION (PALEOCENE), WYOMING

Aurealcaulis crossii gen. et sp. nov., is based on permineralized trunks of an osmundaceous tree fern from the Paleocene Fort Union Formation from near Bitter Creek Station of southwestern Wyoming. This new species is characterized by centripetal (exarch) development of its xylem strands which form part of the leaf traces. Most of the leaf traces depart the stele as two segments that fuse into a single C-shaped petiole vascular strand outside of the outer cortex. Stipular expansions of the petiole bases of this species lack sclerenchyma, and roots arise from the lateral edges of leaf traces in the inner cortex. The family Osmundaceae and subfamily Osmundoideae are slightly emended to accept genera assignable to this family and subfamily with exarch protoxylem in their steles. Foliage similar to Osmunda greenlandica (Heer) Brown, which is possibly the leaf form of A. crossii, occurred next to an axis of this species which was in growth position. This axis was anchored in a lignite suggesting that this species grew under swampy conditions. Aurealcaulis crossii is the first arborescent member of the Osmundaceae of Tertiary age and the second arborescent form in this family reported from the Northern Hemisphere.     

COMPARATIVE STUDIES OF THE NODAL AND VASCULAR ANATOMY IN THE NEOTROPICAL CYATHEACEAE. I. METAXYA AND LOPHOSORIA

Comparative studies of the nodal and vascular anatomy in the monotypic genera Metaxya and Lophosoria are discussed as they relate to the taxonomy and phylogeny of the Cyatheaceae. Both genera are distinctive and primitive with respect to habit, stem and petiole indument, stelar pattern, and nodal anatomy. Metaxya possesses a prostrate, dorsiventral rhizome, whereas a short, upright radial stem occurs in Lophosoria. Trichomes occur on the stems and leaf petioles of these genera. Both Metaxya and Lophosoria have a spiral phyllotaxy, and adventitious buds occur on the petiole bases. The stelar pattern is basically a siphonostele, although frequently a dictyostele is found in Lophosoria. Accessory bundles are lacking in both genera. A characteristic petiole pattern is found in these genera, with an increase in complexity from an undivided strand in Metaxya to the three-parted petiole pattern in Lophosoria. Data from nodal and vascular anatomy indicate that these taxa are distinct from the other genera in the Cyatheaceae and belong in an independent position at the base of the Cyatheoid line, although in some respects an affinity to members of the Dicksoniaceae is indicated.     

Effect of soil moisture depletion on stem shrinkage and photosynthesis of tree seedlings

Effects of soil moisture depletion on stem contraction and photosynthesis of potted 3-year-old white ash (Fraxinus americana L.) and 4-year-old red pine (Pinus resinosa Ait.) seedlings were investigated in greenhouse experiments. White-ash seedlings transpired faster and consequently depleted soil moisture more rapidly than red-pine seedlings. Cumulative stem shrinkage occurred in both species as soils dried and appreciable stem expansion occurred only after soil was reirrigated. Following irrigation, seedlings rehydrated and their stems expanded to about their original diameters within 24 hours in white ash, and in up to 6 days in red pine seedlings. Photosynthesis was decreased in both species as soil dried, but it declined much faster in white ash than in red pine seedlings. Net emission of CO₂ by red pine seedlings occurred after 13 days of soil drying. In contrast, white-ash seedlings did not show net CO₂ release during severe drought. Several days after droughted white-ash and red-pine seedlings were reirrigated, photosynthesis recovered to pre-drought levels. Publication approved by Director of the Wisconsin Agricultural Experiment Station.     

14C Translocation pathways in honeylocust and green ash: Woody plants with complex leaf forms

Long-distance transport in plants requires precise knowledge of vascular pathways, and these pathways differ among species. This study examines the ¹⁴C translocation pathways in honeylocust (Gleditsia triacanthos L.) and green ash (Fraxinus pennsylvanica Marsh.), species with compound leaves, and compares them with those of cottonwood (Populus deltoides Bartr. ex Marsh.), a species with simple leaves. The stem vasculature of honeylocust conforms to a 2/5 helical phyllotaxy and that of green ash to a decussate phyllotaxy. The plastochron is relatively long in both species – 2.5+ days in honeylocust and 4.5+ days in green ash. Consequently, the transition from upward to downward translocation from mature source leaves is abrupt and occurs close to the apex. Export of ¹⁴C from localized treatment positions within a leaf was found to vary both quantitatively and spatially. To determine export patterns, ¹⁴CO₂ was administered to either individual leaflets of once-pinnate or pinnae of bipinnate leaves of honeylocust, and to either individual veins of simple or leaflets of compound leaves of green ash. Transections of either the petiole or rachis base were then examined for ¹⁴C by micro-autoradiography. In all cases, as treatment positions advanced acropetally in the leaves, the bundles translocating ¹⁴C were situated more dorsally in the basal petiole and rachis vasculatures. ¹⁴C was confined to the right side of the vasculature when structures on the right side of a leaf were treated. Compound leaves of both species mature acropetally. Thus, mature basal pinnae of honeylocust and basal leaflets of green ash translocate acropetally to younger leaf parts that are still rapidly expanding. All translocation pathways, both in the stem and leaf, conformed with vascular organization previously determined by anatomical analyses.     

Morphological plasticity in response to shading in three Convolvulus species of different ecological breadth

We evaluated in common-garden experiments the morphological plasticity to shading of three Convolvulus species that occur in Chile and differ in ecological breadth. Convolvulus arvensis L. is a world weed distributed along the country, and is found in open as well as in shaded habitats. Convolvulus chilensis Pers. is a Chilean endemic species typical of coastal habitats, and is found in open to partially open sites. C. demissus choisy occurs only on slopes of the Andes of Chile and Argentina, habitats with high incidence of solar radiation. We hypothesized that the magnitude of phenotypic plasticity to shading of these species would correlate with their ecological breadth. Shading had a significant effect on internode length, petiole length, stem diameter, stem length, number of branches, leaf area, leaf shape, leaf biomass, and specific leaf area. Species differed in all the morphological traits except leaf biomass. A significant Shading × Species interaction in the two-way ANOVA, i.e. differential plasticity to shading of Convolvulus species, was found for petiole length, stem length, number of branches, leaf shape, and specific leaf area. Contrary to our hypothesis, tests of parallelism showed that, in general, the plasticity to shading of C. chilensis (the species of intermediate ecological breadth) was the greatest, and that of C. arvensis (the weed) and C. demissus (the species of narrow distribution) was similar. Issues of ecotype differentiation, in the case of C. arvensis, and the role of life history traits are raised to explain the observed lack of association between ecological breadth and magnitude of phenotypic plasticity.     

CIBOTIUM OREGONENSE: AN EOCENE TREE-FERN STEM AND PETIOLES WITH INTERNAL STRUCTURE

Cibotium oregonense sp. nov. is described from the Upper Eocene of Medford, Oregon. The fossil comprises petiole bases and stem periphery of a large fern preserved via permineralization. A stele devoid of sclerenchymatous sheathing and a petiole vascularized with a large number of leaf traces in a cyatheacean pattern characterize the fossil. A distinctive U-shaped interior series of leaf traces allows assignment to the genus Cibotium. This fossil provides evidence that the genus Cibotium was represented by an arborescent species with large leaves in the Early Tertiary of western North America.     

INTERNAL PHLOEM IN THE PULVINUS OF SOYBEAN PLANTS

Glycine max, like many species of Fabaceae, has pulvini at the base of the petiole. In this structure, the vascular cylinder is constricted and consists of a ring of phloem surrounding a ring of xylem. A combination of light and transmission electron microscopy and histochemistry showed that, in addition, there are groups of internal phloem strands in the pulvinar pith. This was confirmed by direct observation of sieve plates and crystalline P-protein inclusions typical of leguminous sievetube members. Serial sections through the stem–pulvinus–petiole revealed that a spatial reorientation of the vascular tissue in the pulvinus resulted in the formation of internal phloem strands, which are continuous with the external phloem bundles above and below the pulvinus. Using 6(5)carboxyfluorescein (6CF) as a fluorescent tracer of phloem transport, we have shown that the internal phloem was active. In most of the experiments, when 6CF was applied to a source leaf, the internal phloem was not stained when the stem was girdled between the source leaf and the roots. Thus, we suggest that the internal phloem of the pulvinus of soybean is specialized for transport toward the root.     

COMPARATIVE ANATOMY OF THE PETIOLE AND INFRAGENERIC RELATIONSHIPS IN JATROPHA (EUPHORBIACEAE)

Anatomical features of the petiole in several species of Jatropha L. (Euphorbiaceae) are presented as evidence in support of infrageneric relationships. A trilacunar 3-trace nodal pattern is typical for the genus. The vascular supply to the stipules is derived from the branching of the two peripheral leaf traces. The number of vascular bundles range from 11 through 9, 7, 5 and 3, and occur in a ring, as free traces, a medullated cylinder, or as U-shaped free traces. The reduction from nine to three bundles is correlated with the gross morphological features while 11, which occurs only in the section Peltatae (Pax) Dehgan & Webster, presents an increase. Reduction in the number of petiolar traces follows the evolutionary advancement of various taxa. This reduction in traces corresponds with south-north distribution of the species and consequential adaptation to colder and more arid climates in Central America and Africa. Smaller leaves, fewer primary veins and fewer vascular traces have resulted as a response to reduced need for water. Presence of dorsal (super-numerary) bundles which supply the petiolar glands in subgenus Jatropha (= Adenoropium Pax) is considered significant, since African taxa of the section (subsection Pubescentes Pax) have retained these bundles despite the loss of petiolar glands. The latter glands are prominent in the South American and Indian species. Sectional lines in the genus can, therefore, be drawn generally on the basis of numerical constancy and relative uniformity in the arrangement of petiolar traces. The continuity of vascular bundles from the stem into the petiole and variations of bundle arrangements are depicted in three-dimensional drawings.