Correlations between 2C DNA values and habit inCassia (Leguminosae:Caesalpinioideae)

Ten species of the genusCassia show a range of 2C DNA amounts from 1.30 to 2.54 pg at the same ploidy level. Remarkably, a distinct 2-fold increase is depicted by an arboreal speciesC. excelsa while the rest comprising of herbs, trees and shrubs have a range from 1.30 to 1.47 pg. These form a natural grouping with respect to mean DNA amounts which differ by 0.05 pg in the herbs, trees and shrubs respectively.     

Survey of leaf anatomy,especially secretory structures,of tribeCaesalpinieae (Leguminosae,Caesalpinioideae)

We studied leaflet anatomy, emphasizing secretory structures, from herbarium specimens of 128 species of 44 genera of tribeCaesalpinieae, using clearings, resin sections, and scanning electron microscopy. These observations, combined with those from our three earlier papers, provide a survey of 210 species representing all genera. Seventy-three species had secretory structures: 21 had glands or gland-like trichomes, 40 had living mesophyll idioblasts, and nine had cavities (three species each had two different types). Five additional species, all inCercidium (Caesalpinia group), had paired or clustered large spheroidal, thick-walled, empty cells (veinlet idioblasts) interconnected by perforation plate-like gaps. Secretory structures have systematic significance at various taxonomic levels.     

Leaf anatomy inCaesalpinia andHoffmannseggia (Leguminosae,Caesalpinioideae) with emphasis on secretory structures

Leaflets of 65 species ofCaesalpinia s.l. and seven species ofHoffmannseggia were studied in clearings supplemented by resin sections and scanning electron microscopy. Three types of secretory structure occurred among 46 species; in 43 species they were distributed mutually exclusively (external glands: 8 species; internal cavities: 5 species; idioblastic cells: 30 species); three other species each had two types. Species with secretory structures conform mostly to proposed subgenera and informal groups. Other unusual features were external glands with internal spaces, thickened walls or conspicuous localized wall thickenings in epidermal cells or mesophyll cells of certain species, and differentially stained epidermal cells surrounding stomata. Prismatic crystals predominate but druse crystals also occur.     

Breeding systems and pollination inVigna minima (Leguminosae,Papilionoideae)

Four types of floral breeding systems—(i) chasmogamy, (ii) aerial pseudocleistogamy, (iii) subterranean pseudocleistogamy and (iv) obligate subterranean true cleistogamy—are observed in the populations ofVigna minima inhabiting the Western Ghats (India). Five categories of phenotypes are recognized based on the number and kinds of floral breeding systems found in a given individual. The frequencies of different categories of phenotypes not only show intra- and interpopulation variation, but also fluctuate from generation to generation suggesting differences in the genetic structure of populations. This polymorphism in the breeding system of a single species is unique and may be adaptive. Obligate subterranean true cleistogamy and amphicarpy appear to be adaptations to jungle fires and soil erosion.—The flowers are of the flag-blossom type and insect visitors act as tripping agents. The tripping mechanism together with the polymorphic floral breeding system result in a balanced mixture of selfing and outcrossing. Such a recombination system may enhance the fitness ofV. minima which is essentially a colonizing species.     

Allozyme variation and phylogeny in annual species ofCicer (Leguminosae)

Allozymic variation at 30 isozyme loci was examined electrophoretically in nine annual and one perennial species ofCicer. While most of the accessions examined were monomorphic, species can be differentiated on the basis of their enzyme phenotypes. Several groups of species were identified based upon genetic distance values. For example,C. arietinum, C. reticulatum, andC. echinospermum shared the same alleles for most of the loci exmained. PerennialC. anatolicum is also closely related to this group. Similarly,C. judaicum, C. bijugum, andC. pinnatifidum formed another group. Two annual species,C. chorassanicum andC. yamashitae clustered together, whereasC. cuneatum was the most distantly related species. Correlations were found between genetic distances and geographic distribution. Results from enzyme electrophoresis tend to support the previously reported taxonomic treatments based upon crossability and morphological similarity. However,C. yamashitae, which has been classified in the second crossability group, is quite distinct genetically and morphologically from the remaining species of the group. An isozyme gene duplication observed in the genus suggested the monophyletic origin of the species examined in the present study.     

A new species of Chamaecrista Moench (Caesalpiniaceae) from interior Bahia,Brazil

Chamaecrista arboae, a species of sect.Absus ser.Absoideae newly discovered on Chapada Diamantina in interior Bahia, Brazil, is described, figured, and discussed.     

A phenetic study of Cassia sensu lato (Leguminosae-Caesalpinioideae: Cassieae: Cassiinae) in Thailand

Cassia L. sensu lato, a large heterogeneous genus of flowering plants, occurs naturally in the tropics around the world. Recent works based on floral morphology have supported a division of this genus into three genera, namely Cassia L. s. str., Chamaecrista Moench and Senna Mill. In order to investigate this new classification, 508 specimens of 18 taxa of the genus Cassia s.l. grown in Thailand were analyzed using cluster analysis and canonical discriminant analysis. The total 32 vegetative and reproductive morphological characters were employed in these analyses. In cluster analysis, Cassia s.l. can be separated into four groups, respectively viz. Chamaecrista, Senna alata, Senna and Cassia s /str. The four-cluster grouping is discussed. From a canonical discriminant analysis using the four-cluster grouping as a priori groups, it can be concluded that Cassia s. str., Senna, and Chamaecrista are indeed distinct taxa. The three most important characters that separate the three genera are filament length, fruit length, and ovary stalk length. These quantitative characters, together with some qualitative characters, were useful in constructing an identification key to these genera. Among the three genera, it was also found that Senna is rather a heterogeneous taxon. The difference between the studied species was discussed.     

Systematics and randomly amplified polymorphic DNA in the genusLeucaena (Leguminosae,Mimosoideae)

Randomly amplified polymorphic DNA (RAPD) was used to examine genomic diversity in taxa of the neotropical legume genusLeucaena. Data were analysed using both similarity- and parsimony-based approaches and the data compared to a parsimonybased analysis of chloroplast DNA restriction fragment length polymorphisms (RFLP). Distance-based methods of RAPD analysis produced groups inconsistent with those identified by RFLP analysis. Parsimony-based analysis of the data produced groupings largely consistent with those identified using RFLPs. The major differences were grouping of the two subspecies ofLeucaena diversifolia (subsp.diversifolia and subsp.stenocarpa) in the RAPD tree, but their separation in the RFLP tree. The value of RAPD data in systematics as a result of these data and our understanding of the molecular basis of RAPDs are discussed.     

Phylogenetic relationships within Chamaecrista sect. Xerocalyx (Leguminosae, Caesalpinioideae) inferred from the cpDNA trnE-trnT intergenic spacer and nrDNA ITS sequences

Chamaecrista belongs to subtribe Cassiinae (Caesalpinioideae), and it comprises over 330 species, divided into six sections. The section Xerocalyx has been subjected to a profound taxonomic shuffling over the years. Therefore, we conducted a phylogenetic analysis using a cpDNA trnE-trnT intergenic spacer and nrDNA ITS/5.8S sequences from Cassiinae taxa, in an attempt to elucidate the relationships within this section from Chamaecrista. The tree topology was congruent between the two data sets studied in which the monophyly of the genus Chamaecrista was strongly supported. Our analyses reinforce that new sectional boundaries must be defined in the Chamaecrista genus, especially the inclusion of sections Caliciopsis and Xerocalyx in sect. Chamaecrista, considered here paraphyletic. The section Xerocalyx was strongly supported as monophyletic; however, the current data did not show C. ramosa (microphyllous) and C. desvauxii (macrophyllous) and their respective varieties in distinct clades, suggesting that speciation events are still ongoing in these specimens.     

Karyotypic and chloroplast genomic diversity inMedicago sect.Lupularia (Leguminosae)

Studies were made on the chromosome complements and chloroplast genomes ofMedicago lupulina andM. secundiflora, which comprise sectionLupularia ofMedicago. Both types of analyses indicated more substantial differences between these species than suggested by external morphology.Medicago lupulina has a relatively asymmetrical karyotype in terms of centromeric position and relative length. The karyotype ofM. secundiflora is comparatively more asymmetrical in centromeric position and reduced in absolute size but exhibits greater symmetry in relative length. The restriction endonuclease fragmentation patterns of the chloropiast DNA of these two species (with Bam HI, Eco RI, Bgl II, and Xho I) show little similarity, with only 17% of the fragments matching in size. The lack of interspecific congruence among data of morphology, karyology and cpDNA inLupularia is contrary to consistency exhibited among these data inMedicago subsect.Intertextae.     

Oriole pollination ofErythrina breviflora (Leguminosae): Evidence for a polytypic view of ornithophily

Erythrina breviflora is visited by large numbers of passerine birds of which orioles (Icterus: Icteridae) are the primary pollinators. The flowers produce large quantities of nectar but they are rarely visited by hummingbirds. Inflorescence and floral morphology, and low levels of sucrose in the nectar probably explain the rarity of foraging hummingbirds. A comparison of Old WorldErythrina and their pollinators with New World species pollinated by orioles and hummingbirds suggests that parallel evolution has occurred. When the comparison is expanded to include other species pollinated by orioles, it is clear that various New WorldIcteridae, Thraupidae, etc. are ecological equivalents of Old WorldOriolidae, Pycnonotidae, Sturnidae, etc. and that flowers pollinated by these birds have similar characteristics.     

Pollen-ovule patterns in tribeTrifolieae (Leguminosae)

Relative pollen and ovule production in the genera of the legume tribeTrifolieae is explored particularly as to howMedicago with its explosive pollination mechanism compares with its allies.Medicago produces much larger, although much fewer pollen per ovule than the other five genera in the tribe; this is interpreted as a consequence of its highly specialized, irreversible pollination mechanism, which allows only one effective exchange of pollen with pollinators.Melilotus andTrifolium produce a comparatively large quantity of pollen; this can be related to their floral characteristics requiring abundant pollen to achieve fertilization. InMedicago andTrigonella, annuals convert a higher proportion of pollen grains and ovules into seeds than perennials.     

The characterisation and identification of a naturally occurring hybrid in the genusLeucaena (Leguminosae: Mimosoideae)

Phytogeographical, morphological, and molecular evidence for the widespread but sporadic occurrence of sterile hybrids betweenLeucaena leucocephala subsp.glabrata andL. esculenta subsp.esculenta in South-Central Mexico is presented. Most morphological and DNA characters studied in the putative hybrids showed states intermediate between the proposed parental taxa. The occurrence of non-additive nuclear ribosomal DNA phenotypes is discussed and the need to use a suite of nuclear taxon-specific markers to determine hybridity is emphasized. The origin of the hybrid is discussed in relation to the disruption of the distributions of both parental taxa through use by man as minor food plants, providing another example of the important influence of human interference on the evolution ofLeucaena. The successful use of dried leaf material as a source of DNA is highlighted as an efficient way to identify sterile hybrids at the molecular level.     

Taxonomic implications of genome size for all species of the genus Gasteria Duval (Aloaceae)

Nuclear DNA content (2C) is used as a new criterion to investigate all species of the genus Gasteria Duval including the three recently described species Gasteria polita van Jaarsv., G. pendulifolia van Jaarsv. and G. glauca van Jaarsv.. The 122 accessions investigated have the same chromosome number (2n=2x=14), with exception of three tetraploid plants found. The nuclear DNA content of the diploids, as measured by flow cytometry with Propidium Iodide, is demonstrated to range from 32.8–43.2 pg. This implies that the largest genome contains roughly 10¹⁰ more base pairs than the smallest. Based on DNA content the species could be divided in five groups: G. rawlinsonii Oberm. with 32.8 pg, 13 mostly inland species with 34.3–36.0 pg, five coastal species with 36.5–39.0 pg and Gasteria batesiana Rowley with 43.2 pg. The thirteen species with 34.3–36.0 pg could be divided further, in a group of eight species occupying mainly very restricted areas with 34.3–35.1 pg and a second group of five species with 35.2–36.0 pg mainly occupying large areas. These five groups did not coincide very well with the two sections and four series of Gasteria based on a cladistic analysis by van Jaarsveld et al. (1994). Based on its long leafy branches, location in the centre of Gasteria species distribution and its by far lowest DNA content, G. rawlinsonii might be the most primitive member of the genus. Nuclear DNA content as measured by flow cytometry is shown to be relevant to provide additional information on the relationships between Gasteria species.     

Aspects of floral structure and phenology in the genusConophytum (Mesembryanthemaceae)

The complex floral structure in the southern African genusConophytum (Mesembryanthemaceae; 77 spp.) is described in detail and assigned to three basic floral types, two of which can be divided into two subtypes. Correlations between structural features and phenological patterns are demonstrated and discussed in the family context as well as in relation to the systematic subdivision of the genus.     

The morphology of styles and stigmas inVicia (Leguminosae), and its systematic implications

The morphology and development of styles and stigmas ofVicia, one of the five genera of tribe Vicieae, were studied by scanning electron microscopy to contribute to a revision of infrageneric classification. Among the 22 species examined, variations were found as to: (1) whether a boundary between stigma and style is V-shaped when viewed from the adaxial side or not; (2) whether stylar hairs sprout on all sides of the style or only on the abaxial side; (3) whether a hairy area of the style connects with the stigma area first at lateral sides or at an adaxial side; (4) whether styles are tapered or bottle-neck-shaped; (5) whether styles are straight or bend abaxially. Based on these variations, five morphological types of styles and stigmas were provided with a diagnostic key. Comparisons with related tribes Cicereae, Coronilleae, Galegeae, Hedysareae, Loteae and Trifolieae as possible outgroups suggested that the V-shaped boundary between stigma and style is a synapomorphy of some species withinVicia, and that a dorsally compressed and abaxially tufted style, which was distributed in separate subgenera and sections sensu Kupicha but is now known to occur together with the V-shaped boundary, has evolved only one time in the genus, rather than more than once as supposed earlier.     

Calcium oxalate crystals and crystal cells in the leaves ofRhynchosia caribaea (Leguminosae: Papilionoideae)

Summary The development and distribution of calcium oxalate crystals, stomates and hairs were studied in the first trifoliolate leaf ofRhynchosia caribaea (Leguminosae: Papilionoideae, Phaseoleae). Using light and transmission electron microscopy, the crystals were shown to occur in both bundle sheath and mesophyll cells. Crystal distribution and shapes are characteristic forRhynchosia. Crystals develop late in leaf development in contrast to the stomates and hairs. As these latter two structures decrease in number per unit area with leaf age, crystal number increases.     

Taxonomic implications of life cycle and basidium morphology of Ochropsora ariae and O. nambuana (Uredinales)

Ochropsora ariae was found to host-alternate between Anemone pseudo-altaica and Aruncus dioicus var. tenuifolius and Ochropsora nambuana between Anemone flaccida and Elaeagnus multiflora var. hortensis in Japan. Both species produced a sessile, thin-walled, cylindrical probasidium (teliospore), which turned into a four-celled metabasidium by continuous apical elongation of the probasidium. Several probasidia of O. nambuana were produced from a basal basidiogenous cell in a sorus hymenium. Life cycle and probasidium/metabasidium morphology showed the taxonomic identity of Ceraceopsora elaeagni with O. nambuana. Developmental morphology of the basidium found in the two Ochropsora species raised a question against the taxonomic separation of Ochropsora and Aplopsora.     

Seed ontogeny of Chamaecrista and its systematic implications in Cassiinae (Leguminosae, Caesalpinioideae)

The genus Chamaecrista originates from the dismembering of Cassia L., which was elevated to the level of subtribe Cassiinae, giving rise to Cassia sensu stricto, Chamaecrista, and Senna. Phylogenetic analysis has suggested that Cassiinae is not monophyletic. The relationships between its genera are not clear, because they sometimes appear close to Chamaecrista and Senna and at other times close to Senna and Cassia. We describe here development of the seeds of three species of Chamaecrista and compare our data with information published in the literature for Cassiinae and non-Cassiinae legumes. The ovules appear well conserved in Cassiinae, differing only in the length of the funiculus. In terms of seed development, the shape of the endosperm haustorium is similar in Senna and Chamaecrista. Chamaecrista shares more characteristics of its mature seeds with Senna than with Cassia. Chamaecrista and Senna have variable seed shapes, the presence of pleurograms, the absence of root cap primordia, a short epicotyl, and the cotyledonary mesophyll tends to be dorsiventral. These seed characteristics place Senna close to Chamaecrista and distance it from Cassia. We also observed characteristics unique to Chamaecrista, for example the occurrence of multiple pleurograms, a partially multiplicative seed coat, and the presence of embryonic colleters.