Differences in shoot regeneration response from cotyledonary node explants in Asiatic Vigna species support genomic grouping within subgenus Ceratotropis (Piper) Verdc.

The efficiency of any plant regeneration system lies in part in its wide applicability to diverse genotypes. In Asiatic Vigna, cotyledon and cotyledonary node explants from 4-day-old seedlings of 27 genotypes were cultured in a medium consisting of MS salts, B5 vitamins, 3.0% sucrose and 1.0 mg l^-1 BA. Direct and efficient multiple shoot regeneration (80–100%) from the cotyledonary nodes was obtained in all epigeal species namely radiata, mungo, aconitifolia, subspecies radiata var. sublobata, mungo var. silvestris and in the hypogeal but allotetraploid glabrescens. In contrast, two other hypogeal species V. angularis and V. umbellata failed to initiate shoots from the nodes. However, adventititious shoots developed at the basipetal cut (hypocotyl) in 35–67% of V. angularis explants. These results provide evidence in support of the existing genomic grouping within subgenus Ceratotropis, which designates AA, A₁A₁ and A₁A₁/- to epigeal, hypogeal and the allotetraploid species, respectively. Mean shoot production ranged from 3.3 to 10.4 shoots per explant during the first subculture and varied significantly among the responsive genotypes within 4 species. Additional shoots were obtained in all genotypes after subsequent subculture. However, cotyledons were not as regenerable as cotyledonary node explants. Although significant differences in rooting were observed among the shoots of the 15 genotypes, the response was generally higher in MS basal medium (MSO) than in MS with 1.0 mg l^-1 IAA. Regenerated plants were successfully transferred to soil (50–100% survival rate) and all surviving plants were reproductively fertile. This revised version was published online in June 2006 with corrections to the Cover Date.     

Restionaceae seedlings: Morphology,anatomy and systematic implications

Restionaceae differ from most monocot families in having both epigeal and hypogeal germination. The green cotyledons associated with epigeal germination have a central vascular strand as found in most epigeal monocotyledons. In some genera the cotyledon may have a hairpin‐like structure, also described for Anthericaceae. The cotyledon of the hypogeal seedlings is short, without green pigment and largely remains embedded in the seed coat. Hypogeal germination is correlated with large, woody, indehiscent, frequently myrmecochorous nuts, while epigeal germination is found in species with smaller indehiscent nutlets or seeds, dispersed in a variety of ways. The primitive condition is most likely epigeal germination. In hypogeal seedlings of some African and Australian taxa an epicotyledonary rhizome is found between the primary root and the first leaves. Seedlings of African Restionaceae frequently have elongated culm internodes, whereas in the Australian species studied, internodes are very short, resulting in a cluster of seedling leaves. The leaf blades, which in most species are only found on the seedlings, are very simple anatomically. However, they appear to be unifacial, similar to the leaf blades of Anarthria (Anarthriaceae). The anatomical specialisations in the blades mirror those recorded for the culm anatomy. These observations are consistent with the hypothesis that Centrolepidaceae may be neotonous Restionaceae. They also corroborate the morphology of the African Restionaceae, and the presently accepted phylogeny of the African genera of Restionaceae.     

Comparative studies of the vascular system of node-leaf continuum in woody ranales

The vascularization of the node-leaf continuum in the first to eighth foliage leaves of the first-year plant ofMagnolia virginiana is investigated. The cotyledonary node is a 4-trace, 3-lacunar type. Vascularization in the cotyledonary node is fundamentally different from that in the folair node of the same plant. As a result, the cotyledonary vascularization is only described but not compared to that in the foliar node-leaf continuum. Considerable diversity occurs in the node-leaf vascularization of the first-year plants. A 5-trace, 4-lacunar vascular system is constant in the lower folair nodes; this is considered to be the fundamental vascular pattern in the node-leaf continuum of the species. In contrast, the nodal anatomy and petiolar vascularization fluctuate widely in the third to eighth leaves of the first-year plants. Variation is found not only between different nodes of a single plant but even in the corresponding nodes of different individuals. The evidence clearly indicates that variation always correlates with certain members of the leaf-trace complement; thus, either the ventral and/or marginal lateral bundles undergo phylogenetical reduction or amplification.     

Direct shoot regeneration from cotyledonary nodes as a marker for genomic groupings within the Asiatic Vigna (subgenus Ceratotropis {Piper} Verdc.) species

In vitro culture of cotyledonary node (cn)explants, decapitated and intact seedlings of four different AsiaticVigna species (germinated and subcultured in MS-B5 mediumwith 1.0 mgl^–1 BA) resulted in axillaryshoot formation only from the epigeal V. radiata and thehypogeal but allotetraploid V. glabrescens. The hypogealspecies V. angularis and V. umbellatafailed to exhibit this response. Shoot decapitation invivopromoted similar response only in V. radiata, indicatingthat in vitro culture in BA-supplemented medium isrequiredby V. glabrescens to achieve the same response.Histological observations of the cn explants from 4-d-oldin-vitro-germinated seedlings at d 0(inoculation day), d 4 and d 8 (after inoculation) revealed the formation ofprimary axillary shoots (pas) in both V. radiata andV. glabrescens. Secondary axillary branching at the baseofthe pas was observed at 8 d. Further examination by scanningelectron microscope (SEM) confirmed the presence of shoot buds enveloped by atleast two leaf primordia in the explants at d 0 in all epigeal species namelyV. radiata, V. mungo and V.aconitifolia together with the hypogeal but allotetraploidV. glabrescens. Consistently, these structures were absentin V. angularis and V. umbellata.Present histological and SEM observations support the previous findings ofAvenido and Hattori (Plant Cell Tissue Organ Cult, 1999) that the induction ornon-induction of shoots directly from the nodes of invitro-cultured cn explants is a new marker corresponding to thegenomic grouping within the Asiatic Vigna species. Basedonhybridization studies, Dana (Breeding Methods for Improvement of Crops, 1980)designates AA, A₁A₁ and A₁A₁/- toall epigeal, hypogeal and the hypogeal but allotetraploid AsiaticVigna species, respectively. Moreover, these findingsproved that the differential in vitro regenerationresponse(i.e., response to BA) arises from inherent anatomical and developmentaldifferences, and is supportive of the genomic grouping within subgenusCeratotropis of the genus vigna.     

COMPARATIVE ONTOGENETIC STUDIES IN YOUNG SPOROPHYTES OF TREE FERNS. I. A PRIMITIVE AND AN ADVANCED TAXON

Ontogenetic studies of young sporophytes were undertaken to determine anatomical and morphological differences between a primitive (Lophosoria quadripinnata) and an advanced (Sphaeropteris elongata) tree fern. In both species the first leaf is simple, fanshaped, and possesses dichotomous venation. Later-formed leaves exhibit either a pinnate or bipinnate pattern of laminar dissection. As the sporophyte matures, the stelar pattern changes from a protostele to an amphiphloic siphonostele, and finally to a dictyostele in Sphaeropteris. Medullation of the protostele occurs either prior to or after the formation of the first leaf trace in both species. Differentiation of xylem in the shoot is acropetal and the appearance of mature protoxylem occurs closer to the apical meristem in Sphaeropteris. The nodal pattern varies within each species with a no gap 1-trace pattern characteristic for the first two or three leaves, depending upon the taxon. In Lophosoria subsequent leaves possess a unilacunar 1-trace nodal pattern, whereas a complete nodal series (1 gap 1-trace to 1 gap 6-trace) occurs in Sphaeropteris. Fusiform leaf gaps are noted in both species. The shoot apical meristem is dominated by a single apical cell, with an organized apical cell first found in P₂. Stem, root, and petiole anatomy are discussed.     

Seedling morphology of three sympatric savanna species of Byrsonima: First evidence of cryptogeal germination in Malpighiaceae and an overlooked seedling type in eudicots

Byrsonima crassifolia (L.) Kunth, B. coccolobifolia Kunth and B. verbascifolia (L.) DC. (Malpighicaceae) are sympatric species with high ecological importance in the Roraima savannas of northern Brazil. The three species can be distinguished by seedling characters. The phanerocotylar, epigeal, foliaceous seedling of B. crassifolia is similar to other forest species in the genus. On the other hand, both B. coccolobifolia and B. verbascifolia have phanerocotylar, hypogeal, foliaceous seedlings, representing a newly defined seedling group among eudicot seedling types. Byrsonima verbascifolia has a reduced epicotyl and short subsequent internodes, whereas the long cotyledonary petioles are diagnostic for B. coccolobifolia. Both B. coccolobifolia and B. verbascifolia have cryptogeal germination, which involves characters that presumably protect the plumule from the recurrent fires they are subjected in savannas (e.g., plumule burying, cotyledonary node below the soil surface, and fusion of cotyledonary petioles). This is the first report of cryptogeal germination in the Malpighiaceae as well as in Neotropical eudicots.     

An unusual case of epigeal cryptocotylar germination in Rollinia salicifolia (Annonaceae)

An unusual case of epigeal cryptocotylar germination found in Rollinia salicifolia Schltdl. (Annonaceae) is described and is discussed in relation to the terminology used for germination studies. The terms cryptocotylar and phanerocotylar are used to describe the permanence of cotyledons within the seed coat or endocarp; the terms epigeal and hypogeal are used to refer the position of cotyledons in relation to ground level. The terms to describe position about ground level and permanence of cotyledons within the seed coat or endocarp are not used simultaneously in many papers, and some authors consider the terms cryptocotylar and hypogeal to be synonyms. Cases of epigeal cryptocotylar germination seem to be scarce in the literature. The morphological characters shown by R. salicifolia seeds and seedlings − a non-chlorophyllous embryo, abundant endosperm, thick woody seed coat, thickened hypocotyl and non-photosynthetic haustorial cotyledons − are closely related to its epigeal cryptocotylar germination. This is the first record of this type of germination in Argentina.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 53–56.     

A Comparative Study of Cotyledons as Assimilatory Organs

Cotyledons of 11 species were studied at a number of stagesof germination. The hypogeal pea and runner bean cotyledonsdid not expand, lost weight, and survived for a relatively shorttime only. They also produced little chlorophyll on exposureto light, possessed no stomata, and had a very low capacityfor ¹⁴CO₂ fixation. The epigeal french bean had cotyledons thatwere basically of the hypogeal type. Although both white andblue lupin cotyledons showed a progressive weight loss, theyunderwent limited expansion and were more persistent than eitherpea or bean. They also produced considerable amounts of chlorophyll,had stomata on both upper and lower surfaces, and fixed restrictedquantities of ¹⁴CO₂. The cotyledons of the other epigeal speciesstudied showed varying degrees of expansion, up to almost fifty-foldin cucumber, and generally maintained or increased in totaldry weight for at least a restricted period. Stomata occurredon both upper and lower surfaces, extensive chlorophyll productiontook place, and ¹⁴CO₂ fixation values were high. Expansion was determined by increase in cell size, and not incell number except in the case of cucumber where both factorswere involved. In species where cotyledon cells were large initiallylittle or no expansion occurred, whereas initial cell size wassmall in cotyledons which expanded to a large extent. Epigeal cotyledons with a high expansion factor possessed othercharacteristics which made them adapted for photosynthesis,whereas epigeal species with lower cotyledon expansion togetherwith hypogeal species were less well adapted. This was not unexpectedin the case of pea and runner bean, but led to the conclusionthat french bean cotyledons are ‘accidentally epigeal’in that they showed virtually no adaptation to an aerial existence.The different capacities of the cotyledons studied suggeststhat they have differing roles in the control of seedling growth.     

VARIATION IN THE ORGANIZATION OF THE STOMATAL COMPLEX IN THE LEAF EPIDERMIS OF MONOCOTYLEDONS AND ITS BEARING ON THEIR PHYLOGENY

Stebbins , G. L., and G. S. Khush . (U. California, Davis.) Variation in the organization of the stomatal complex in the leaf epidermis of monocotyledons and its bearing on their phylogeny. Amer. Jour. Bot. 48(1): 51–59. Illus. 1961.—Using macerated pieces of epidermal tissue from living plants and herbarium specimens, stomatal complexes of 192 species belonging to 49 families of monocotyledons were studied. Four categories are recognized, 2 with 4 or more subsidiary cells surrounding the guard cells, 1 with 2 subsidiaries, and 1 with none. Development of the 2-subsidiary type, studied in acetocarmine preparations of Juncus effusus and Sagittaria montevidensis, resembles that in Gramineae previously described. No correlation was found between type of stomatal complex and either leaf shape or type of xylem vessel, but some correlation exists between this character and type of seed germination, vascular anatomy of seedling, growth habit of mature plant, and geographic distribution. Types with 4 or more subsidiaries are most commonly phanerophytes with tropical distribution, many vascular bundles in the cotyledon, and hypogeal germination. Complexes with 2 subsidiaries occur in many families of a diverse nature, but the most primitive plants with this type are hydrophytes or helophytes with tropical or temperate distribution, 1 vascular bundle in the cotyledon, and epigeal germination. Stomatal complexes without subsidiaries are almost confined to the Liliales and their more specialized derivatives. These plants are predominantly geophytes with temperate or tropical distribution, 2 bundles in the cotyledon, and epigeal germination. Reasons are advanced for suggesting that the type with many subsidiaries is the most primitive and the other 2 types have been derived from it independently by reduction of the number of subsidiary cells.     

Evolution under domestication: contrasting functional morphology of seedlings in domesticated cassava and its closest wild relatives

Although cassava (Manihot esculenta ssp. esculenta) is asexually propagated, farmers incorporate plants from seedlings into planting stocks. These products of sex are exposed to selection, which in agricultural environments should favour rapid growth. To examine whether seedling morphology has evolved under domestication, we compared domesticated cassava, its wild progenitor (M. esculenta ssp. flabellifolia) and their sister species (M. pruinosa) under controlled conditions. Field observations complemented laboratory study. In both wild taxa, the hypocotyl did not elongate (hypogeal germination) and cotyledons remained enclosed in the testa. In domesticated cassava, the hypocotyl elongated (epigeal germination), and cotyledons emerged and became foliaceous. The difference in hypocotyl elongation was fixed, whereas cotyledon morphology varied with environmental conditions in M. pruinosa. Comparative analysis suggests that epigeal germination is primitive in Manihot, that the lineage including wild ancestors of cassava evolved hypogeal germination--which confers greater tolerance to risks in their savanna environment--and that with domestication, there was a reversion to epigeal germination and photosynthetic cotyledons, traits conferring high initial growth rates in agricultural habitats.     

On the structure and evolutionary relationships of the Cerro Cuadrado fossil conifer seedlings*

Seedlings from the Cerro Cuadrado (Jurassic) Petrified Forest in Argentina have been shown to be comparable to extant araucarian seedlings from the sections Eutacta, Bunya and Colombea. Anatomically they are compared to the cone axes and embryos in the fossil cones of Araucaria mirabilis and Pararaucaria patagonica. Two seedlings previously described by Wieland are shown on pith structure to belong to P. patagonica. The remaining turbinate to top-shaped structures are compared with first year extant Bunya and Columbia seedlings and the cone A. mirabilis. Corm-like structures may represent an older seedling stage. From earlier work on the embryonic anatomy and germination stages described here, P. patagonica is deduced to have been epigeal and A. mirabilis hypogeal.     

ONTOGENY OF THE COTYLEDONARY REGION OF CHAMAESYCE MACULATA (EUPHORBIACEAE)

Development of the cotyledonary region in Chamaesyce maculata is described from germination of the seed through formation of the dense mat of branches which characterize this common weed. The cotyledonary node is trilacunar with split-lateral traces. Epicotyl development is limited to a pair of leaves (“V-leaves”) inserted directly above and decussate to the cotyledons. The two V-leaves are also vascularized by three traces and insertion of these traces relative to the vasculature at the immediately subjacent cotyledonary node is asymmetrical; four of the six V-leaf traces arise on one side of the intercotyledonary plane and two arise on the opposite side. Further shoot development is limited to lateral branches that develop sequentially from cotyledonary axillary buds, and then from de novo buds which arise at bases of previously developed lateral branches. The first axillary bud to develop is located on that half of the seedling which supplies the V-leaves with four traces. Development or insertion of the third and fourth branches (first and second de novo branches) relative to the first and second (cotyledonary) branches occurs in two patterns, termed cis and trans. Subsequent de novo branches generally develop between the two most recently developed branches on that half of the seedling, gradually forming a large branch plexus at the cotyledonary region. In mature robust specimens, however, the sequence of lateral branch development may become irregular. Structure of the cotyledonary region of C. maculata does not readily support widely held concepts of homology between the pleiochasium of Euphorbia subgenus Agaloma and the lateral branch system of Chamaesyce.     

Micropropagation of<Emphasis Type="Italic">Schizandra chinensis</Emphasis> BAILLON using glucose from cotyledonary nodes

A protocol for the micropropagation ofSchizandra chinensis has been developed using regenerated shoots from axillary bud explants. In preparing to do so, we found that seed type (i.e., mature vs. pre-mature) significantly influenced the rate of germination. The Woody Plant (WP) medium proved to be superior to the Murashige and Skoog (MS) medium for germination purposes. Multiple shoots were induced from cotyledonary nodes of axenic seedlings on WP media containing 6-benzylaminopurine (BA) alone or in combination with 1-napthaleneacetic acid (NAA). High frequencies of shoot proliferation and the greatest number of shoots per explant (11.6) were observed with the use of 1.0 mg L^-1 BA. We also established a culture method for proliferating shoots by repeatedly subculturing the original cotyledonary nodes on a shoot multiplication medium each time newly formed shoots were harvested. To induce root formation, glucose was supplied as a carbon-source substitution for sucrose. The best rooting rate was obtained from a WP medium supplemented with 3% glucose and 0.5 mg L^-1 NAA. Following transplantation in the field, 82% of the plantlets survived.     

Limited evolutionary divergence of seedlings after the domestication of plant species

The most vulnerable stage in the life of plants is the seedling. The transition from wild to agricultural land that plants experienced during and after domestication implied a noticeable change in the seedlings′ environment. Building on current knowledge of seedling ecology, and on previous studies of cassava, we hypothesise that cultivation should have promoted epigeal germination of seedlings, and more exposed and photosynthetic cotyledons. To test this hypothesis, we phenotyped seedling morpho‐functional traits in a set of domesticated and wild progenitor accessions of 20 Eudicot herbaceous crop species. Qualitative traits like epi‐ versus hypogeal germination, leafy versus storage type of cotyledons, or crypto‐ versus phanerocotyledonar germination, remained conserved during the domestication of all 20 species. Lengths of hypocotyls and epicotyls, of cotyledon petioles, and indices of cotyledon exposure to the aboveground environment changed during evolution under cultivation. However, those changes occurred in diverse directions, depending on the crop species. No common seedling phenotypic convergence in response to domestication was thus detected among the group of species studied here. Also, none of the 20 crops evolved in accordance with our initial hypothesis. Our results reject the idea that strong selective filters exerted unconsciously by artificial selection should have resulted in generalised channelling of seedling morphology towards more productive and more herbivore risky phenotypes. This result opens up unexplored opportunities for directional breeding of seedling traits.     

双子叶植物出土幼苗根茎转变区维管组织发育动态

关于根茎初生维管系统之间的连接以及与子叶的关系,在文献中已有广泛的论述,有过各种不同的解释。大部分早期关于根茎转变区的文献研究的是初生组织已完成发育的幼苗。这些研究者认为转变区域是根和茎这两种轴器官之间维管组织发生转变、相互连接的区域。但由于茎中的初生维管组织可以认为是叶迹及叶迹的延伸的综合,转变区域应被看作是轴维管系统与叶迹维管系统之间的连接。因此,转变区的研究必须说明根维管系统与最早的真叶叶迹之间的关系。通过对北乌头和大豆胚胎及幼苗维管组织的解剖学研究,本工作显示在出土萌发的双子叶植物中,初生维管组织在根-下胚轴-子叶中形成一连续系统,并完成根与子叶叶迹之间的维管组织过渡转变。而上胚轴中的维管组织是位于根-下胚轴-子叶上方独立形成的第二维管系统。上胚轴中维管组织的分化起始于第一真叶叶迹基部,向上分化进入叶片,向下进入胚轴并在子叶节下方与根-下胚轴-子叶维管系统相连接。真叶叶迹的木质部与下胚轴中靠近韧皮部的后生木质部或次生木质部连接。根与上胚轴之间不存在维管组织的过渡、转变,而只是在同样发育方向的组织中有一种直接的简单的连接．     

<Emphasis Type="Italic">In vitro</Emphasis> shoot regeneration from cotyledonary node explants of a multipurpose leguminous tree <Emphasis Type="Italic">Pterocarpus marsupium</Emphasis> Roxb.

Summary A protocol has been developed for in vitro plant regeneration from cotyledonary nodes of Pterocarpus marsupium Roxb. Multiple shoots were induced from cotyledonary nodes derived from 20-d-old axenic seedlings grown on Murashige and Skoog (MS) medium containing 2.22–13.32 μM benzyladenine (BA) or 2.32–13.93 μM kinetin alone or in combination with 0.26 μM α-naphthaleneacetic acid (NAA). The highest frequency of responding explants (85%) and maximum number of shoots per explant (9.5) were obtained on MS medium supplemented with 4.44 μM BA and 0.26 μM NAA after 15 wk of culture. A proliferating shoot culture was established by repeatedly subculturing the orginal cotyledonary nodal explant on fresh medium after each harvest of the newly formed shoots. Nearly 30% of the shoots formed roots after being transferred to half-strength MS medium containing 9.84 μM indole-3-butyric acid after 25 d of culture. Fifty percent of shoots were also directly rooted as microcuttings on peat moss, soil, and compost mixture (1∶1∶1). About 52% plantlets rooted under ex vitro conditions were successfully acclimatized and established in pots.     

<Emphasis Type="Italic">In vitro</Emphasis> shoot regeneration from cotyledonary node explants of a multipurpose leguminous tree, <Emphasis Type="Italic">Pterocarpus marsupium</Emphasis> roxb

Summary A protocol has been developed for in vitro plant regeneration from cotyledonary nodes of Pterocarpus marsupium Roxb. Multiple shoots were induced from cotyledonary nodes derived from 20-d-old axenic seedlings grown on Murashige and Skoog (MS) medium containing 2.22–13.32 μM benzyladenine (BA) or 2.32–13.93 μM kinetin alone or in combination with 0.26 μM α-naphthaleneacetic acid (NAA). The highest frequency for shoot regeneration (85%) and maximum number of shoots per explant (9.5) were obtained on the medium supplemented with 4.44 μM BA and 0.26 μM NAA after 15 wk of culture. A proliferating shoot culture was established by repeatedly subculturing the original cotyledonary nodal explant on fresh medium after each harvest of the newly formed shoots. Nearly 30% of the shoots formed roots after being transferred to half-strength MS medium containing 9.84 μM indole-3-butyric acid (IBA) after 25 d of culture. Fifty percent of shoots were also directly rooted as microtuttings on a peat moss, soil, and compost mixture (1∶1∶1). About 52% of plantlets were successfully acclimatized and established in pots.     

Long-term post-fire resprouting dynamics and reproduction of woody species in a Brazilian savanna

Resprouting is an efficient life history strategy by which woody savanna species can recover their aboveground biomass after fire. However, resprouting dynamics after fire and the time it takes to start producing flowers and fruits are still poorly understood, especially for the Brazilian savanna (Cerrado biome), where fire is an important driver of vegetation structure and ecosystem functioning. We investigated the resprouting dynamics and production of flowers and fruits of 26 woody species (20 tree and 6 shrub species for a total of 485 individuals) that were burned and the production of flowers and fruits for a subset of 12 species (139 individuals) in an unburned area in a Brazilian savanna. We classified the species’ resprouting strategies as hypogeal (at the soil level, with main stem death), epigeal (on the main stem or crown), and hypogeal + epigeal. We used generalized linear mixed-effect models to identify the post-fire recovery patterns for five years. Individuals with basal resprouts (hypogeal and hypogeal + epigeal resprouting) produced an average of 6 basal resprouts, but only 33% of resprouts survived after five years. Individuals in burned areas produced fewer flowers and fruits than individuals in unburned areas. At least a subset of individuals in all the resprouting strategies started to produce flowers and fruits in the first-year post-fire. About 68% of the species with hypogeal resprouts produced flowers and fruits in the first-year post-fire, but the intensity of flowering and fruiting was lower compared to individuals with other resprouting strategies over time. Although woody species have invested in post-fire growth and sexual reproduction in all resprouting strategies, the long time needed to recover these processes can make these species more vulnerable to frequent fires.     

INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: JUGLANDACEOUS WINGED FRUITS

The winged fruits of Engelhardia have been reported in many early Tertiary floras in the northern Hemisphere. Recent systematic revisions of the extant genera, Engelhardia, Oreomunnea, and Alfaroa provide a helpful guide to the study of the fossil fruits. Fruit form, venation, nut septations and flower parts are features that separate the extant Asian Engelhardia from the American Oreomunnea. Four types of fossil winged fruits can be recognized in Middle Eocene sediments of southeastern North America: Engelhardia, Paraoreomunnea gen. n., Paleooreomunnea gen. n., and Pararengelhardia. Both Paleooreomunnea and Paraengelhardia represent extinct lines; no living forms have similar winged fruits. The fossil fruits of Engelhardia and Paraoreomunnea are similar to the fruits of extant Engelhardia and Oreomunnea, respectively. The fossil taxa reported in this paper were sympatric. The present allopatric distribution of Engelhardia and Oreomunnea is the result of Neogene regional extinctions. Engelhardia and Oreomunnea have probably been distinct genera since early Paleogene time.     

Micropropagation of Crataeva nurvala

A simple protocol for mass multiplication of Crataeva nurvala, a medicinal tree, from seedling-derived explants is described. Six different types of explants (cotyledonary nodes, epicotyl nodes, hypocotyl segments, first pair of leaves, cotyledons, and root segments) developed shoots on Murashige and Skoog's (MS) basal medium or the same supplemented with different concentrations of 6-benzylaminopurine (BAP). Among the explants tested for caulogenic potential, only the epicotyl and cotyledonary nodal explants developed shoots on MS basal medium, while on BAP (0 – 2.0 mg dm⁻³) adjuvated media all the explants exhibited caulogenesis. The optimum concentration of BAP varied for these explants. The shoots could be rooted on half strength MS with 0.02 mg dm⁻³ α-naphthalene acetic acid to get plants, which have been transferred to soil. The explants from in vitro regenerated shoots also possessed a similar caulogenic potential. This revised version was published online in July 2006 with corrections to the Cover Date.