Bobgunnia, a new African genus of tribe Swartzieae (Fabaceae, Faboideae)

A new genus, Bobgunnia, is established in tribe Swartzieae for the African species of Swartzia. Two new combinations are made: B. fistuloides and B. madagascariensis. The new genus has seeds, unlike the remainder of tribe Swartzieae but like the other tribes of Faboideae. The systematic position of Swartzieae is reevaluated.     

Seed abortion in Pongamia pinnata (Fabaceae)

In Pongamia pinnata only one of the two ovules develops into a seed in most of the pods. Since pollen was not found to be limiting and reduced fertilization could not completely explain the observed frequency of seed abortion, it implied an effect of postfertilization factors. Aqueous extracts of developing seeds and maternal tissue (placenta) did not influence abortion in vitro, suggesting that abortion may not be mediated by a chemical. Experimental uptake of ¹⁴C sucrose in vitro indicated that both the stigmatic and the peduncular seed have similar inherent capacities of drawing resources, but the peduncular seed is deprived of resources in the presence of the stigmatic seed. This deprivation of the peduncular seed could be offset by supplying an excess of hormones leading to the subsequent formation of two seeds in a pod. The prevalence of single-seeded pods in P. pinnata seems therefore to be a result of competition between the two seeds for maternal resources. The evolutionary significance of single-seeded pods in P. pinnata is discussed with respect to possible dispersal advantage enjoyed by such pods.     

Embryology of Clitoria ternatea (Fabaceae)

ABSTRACT

The embryology of Clitoria ternatea was studied. Anthers contain four sporangia. The anther wall comprises an epidermis, an endothecium, a middle layer and a glandular tapetum. Microspore tetrads are tetrahedral and pollen grains are shed at the 2-cell stage. The ovule is campylotropous, bitegmic and crassinucellate. The micropyle is formed by both the integuments. The megaspore tetrad is linear or T-shaped. The chalazal megaspore is functional and embryo sac development follows the monosporic Polygonum type. Endosperm development is of the nuclear type. The chalazal part of the endosperm forms a haustorium. Embryo development follows the Onagrad type.     

A new species of Lathyrus L. (Fabaceae) from Central Apennine (Italy)

Abstract

Lathyrus apenninus, from beech woods margins and scrub in the Central Apennine (Italy), is described as a species new to science. The relationship of L. apenninus with L. linifolius, which it had been confused with, is briefly discussed.     

Galactomannans and a galactoglucomannan in legume seed endosperms: Structural requirements for β-mannanase hydrolysis

A series of galactomannans with varying degrees of galactose substitution have been extracted from the endosperms of legume seeds with water and alkali and the amount of substitution required for water solubility has been determined. Some were heterogeneous with respect to the degree of galactose substitution. The structural requirements for hydrolysis by plant β-mannanase have been studied using the relative rates and extents of hydrolysis of these galactomannans. A more detailed examination of the products of hydrolysis of carob galactomannan has been made. At least two contiguous anhydromannose units appear to be needed for scission. This is similar to the requirement for hydrolysis by microbial enzymes. Judas tree (Cercis siliquastrum) endosperm contained a polysaccharide with a unique composition for a legume seed reserve. Gel chromatography and electrophoresis on cellulose acetate indicated homogeneity. Hydrolysis with a mixture of β-mannanase and α-galactosidase gave a glucose-mannose disaccharide and acetolysis gave a galactose-mannose. These results, as well as the pattern of hydrolysis by β-mannanase were consistent with a galactoglucomannan structure.     

A review of Lecointea (Fabaceae: Swartzieae) in South America

Lecointea (Fabaceae: Swartzieae) is briefly reviewed in order to place in context a new species (L. marcano-bertii Barneby) from western Venezuela and a new Ecuadorian variety ofL. peruviana J. F. Macbr. (var.lasiogyne Barneby). The new taxa are discussed, the new species is illustrated, and a dispersal map and a key to the South American members ofLecointea are provided.     

The genus Zollernia (Fabaceae: Swartzieae) in Bahia,Brazil

The genusZollernia is represented in the state of Bahia by four species, two of which,Z. magnifica andZ. modesta, are described and figured herein. A key to the species known from Bahia and commentary on the new taxa are provided.     

Cotyledon anatomy in the Leguminosae

Cotyledon anatomy has been investigated in approximately 900 species representing all the major tribes of the Leguminosae. Four main cotyledon forms are recognized on the basis of morphological, anatomical and functional criteria. The two modal forms are a leaf-like photosynthetic cotyledon, usually borne in an endospermic seed and occurring in about 60% of species; and a fleshy, storage cotyledon, borne in a non-endospermic seed and occurring in about 30% of species. Two intermediate forms combine the structural and functional characteristics of the modal forms in varying degree. The leaf-like cotyledon is considered to be the basic form from which the others have been derived. Cotyledon anatomy shows correlations with seed size and with taxonomic grouping at the tribal and generic levels and thus provides a set of minor characters of potential taxonomic or phylogenetic value or for use in seed and seedling classification and identification.     

Genetic load,nutrient limitation,and seed production in Lupinus texensis (Fabaceae)

The interaction of mating system and nutrient limitation in determining seed production was investigated in the annual, self-compatible plant Lupinus texensis (Fabaceae). Abortion of developing seeds is a major factor limiting seed production in natural populations (17-28%). Selfing rates are generally low (0.02-0.21), suggesting that deleterious recessive genes may be maintained at significant levels in natural populations. The average inbreeding depression associated with seed development is δ = 0.24. Nutrient limitation reduced seed output across experimental treatments by a factor of 0.22 through decreased production of inflorescences, flowers, and ovules, and by a factor of 0.29 through increased abortion of fruits and of seeds within fruits. Competition for resources among fruits increased the frequency of seed abortion. Moreover, a greater proportion of selfed seeds were aborted as the overall abortion rate increased. Estimates of genetic load may therefore only be appropriate if undertaken in the field, and inbreeding depression may vary from year to year simply due to changes in environmental conditions rather than to underlying genetic changes in populations. The existence of inbreeding depression and the high frequency of abortions suggest that selective abortion favoring outcrossed progeny occurs in natural populations of L. texensis.     

Karyotypic studies on species of Phaseolus (Fabaceae: Phaseolinae)

Ten karyotypes of Phaseolus were analyzed. Possible directions of karyological evolution of those species are suggested. All species studied have karyotypes composed exclusively of metacentric and submetacentric chromosomes, except P. filiformis with all metacentrics, and P. chiapasanus with one pair of subtelocentric chromosomes. Secondary constrictions and satellites are common among species studied. Phaseolus leptostachyus, P. micranthus, and P. macvaughii are considered as aneuploids with 2n= 20, whereas the rest of the species have 2n= 22.     

Hierarchical patterns of paternity within crowns of Albizia julibrissin (Fabaceae)

The floral architecture and phenology of the tree species Albizia julibrissin (Fabaceae) offer the potential for flowers within inflorescences to share common pollen donors. Patterns of paternity within individual tree crowns may differ among isolated individuals and those in populations due to differences in pollinator foraging behavior. To determine how genetic diversity is partitioned within individual seed pools and whether these patterns differ among isolated and population trees, we obtained all fruits from three inflorescences from four clusters from three isolated trees and from three population trees in Athens, Georgia. We assayed 14 polymorphic allozymes to genotype all progeny within singly sired fruits to determine the multilocus genotype of each fruit's pollen donor. Inflorescences had multiple pollen donors, but simulation analyses revealed that redundancy of pollen donors tended to be more likely within inflorescences than randomly across the crown. Analysis of genetic and genotypic diversity indicated that individual maternal trees received pollen from many donors in uneven frequencies. Results suggest that isolated trees receive pollen from slightly fewer pollen donors and experience more within-plant pollinator movement than trees in populations. However, isolated trees receive qualitatively similar pollen from many sources, suggesting that these trees are not effectively isolated and that pollen moves long distances in this species.     

Biflavonoids from the bark roots of Poincianella pyramidalis (Fabaceae)

Poincianella pyramidalis (Fabaceae) is an endemic tree that grows in semiarid regions of Brazil. Phytochemical investigations on the bark roots of this plant led to the isolation of four new biflavonoids named (+)-5-hydroxy-7,4′-dimethoxyflavone-3α-2′′′-hydroxy-4′′′,4′′-dimethoxydihydrochalcone (1), (+)-5,7-dihydroxy-4′-methoxyflavone-3α-2′′′-hydroxy-4′′′,4′′-dimethoxydihydrochalcone (2), (−)-7-hydroxy-4′-methoxyflavone-3α-2′′′,4′′′-dihydroxy-4′′-methoxydihydrochalcone (3), (−)-7,4′-dihydroxy-flavanone-3,8-5′′,6′′,4′′-trihydroxy-flavone (4), and the previously identified compound 4,2′,4′,4′′,2′′′,4′′′-hexahydroxy-3,5′′′-bichalcone (rhuschalcone VI, 5). Their structures were determined by HR-ESI-MS and extensive analyses of NMR spectroscopic data.     

Effect of ovule position within the pod on the probability of seed production in Bauhinia ungulata (Fabaceae)

BACKGROUND AND AIMS: It has been claimed that ovules linearly ordered within a fruit differ in their probabilities of reaching maturity. This was investigated by studying the effect the position of an ovule within the pod has on seed abortion and seed production in Bauhinia ungulata. METHODS: Fruits collected during the dry seasons of 1999, 2000 and 2001 were opened, and the number, position and status of each ovule within the fruit were recorded. A GLM model was used to assess the effects of population, tree identity and ovule position within the pod on ovule fertilization, seed abortion, seed damage and seed maturation in two populations of B. ungulata. KEY RESULTS: Nearly 30% of the ovules were not fertilized in 1999; this percentage dropped to 5% the following two years. Seed abortion (50%) and seed damage (15%) were the same every year during the study period. Only 15% of the initial ovules developed into mature seeds in 1999; this value increased to 35% in 2000 and 2001. However, seed survivorship was dependent on the position of the ovule within the pod; non-fertilized and early aborted ovules were found more often near the basal end of the ovary. The frequency of seed damage was not affected by position. Mature seeds were found mainly in the stylar half of fruits, where ovules are likely to be fertilized by fast pollen tubes. CONCLUSIONS: The pattern of seed production in B. ungulata is non-random but is dependent upon the position of the ovule within the pod. The results suggest that the seeds produced within a fruit might differ in their vigour.     

Leaf epidermal micromorphology of Cercis (Fabaceae: Caesalpinioideae)

The micromorphology of leaf epidermal cells and stomata of all eight species and one form (11 samples) of Cercis were observed by scanning electron microscopy and light microscopy. Both the adaxial and abaxial epidermal cells are polygonal or irregular in shape; the anticlinal walls are straight and arched or undulate. Two types of stomata, which occur only on the abaxial surface of the leaves, are found in the genus. The atypical paracytic type is present in only one species, Cercis chingii, and the anomocytic type is present in all other species. Interspecific differences are minor in the genus with regard to leaf epidermal characters, except for C. chingii, which is characterized by atypical paracytic‐type stomata, a two‐lipped outer stomatal rim, the highest stomatal density and undulate and densely pitted anticlinal walls in the adaxial epidermis. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 539–547.     

Biogeographical,ecological and morphological structure in a phylogenetic analysis of Ateleia (Swartzieae,Fabaceae) derived from combined molecular,morphological and chemical data

A phylogenetic analysis of combined morphological, chemical and ITS/5.8S sequence data reveals that species of Ateleia are often more genetically than morphologically divergent, and that species thought to be most closely related morphologically are distant relatives within the genus. Ateleia shows niche conservatism, with most species confined to seasonally dry tropical forest in Central America and the Caribbean, and fewer species in the same biome in South America. Four independent transitions to wet forests may have occurred in the genus. The estimated ages of Ateleia lineages spanning Central and South America are either older or younger than the estimated age of closure of the Isthmus of Panama. The older dates clearly suggest that over‐water dispersal is responsible for the distribution of Ateleia that includes the Caribbean Islands. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 39–53.     

Chromosomal Variation in Lotus alpinus (Fabaceae)

Abstract An accession of Lotus alpinus Schleich. (2n=2x=12) from Turkey in which B chromosomes have been found was studied morphologically and karyologically. Chromosome numbers were observed in 519 cells from nine plants which all exhibited mixoploidy (2n=11, 12, 12 + 1B, 12 + 2B and over 20). Keel tip color, stem pubescence, and inflorescence size differed from a collection of this species from Switzerland. While the percentage of total lengths of the chromosome complements and the relative chromosome lengths in the two accessions were very similar, the total complement lengths differed considerably (23.14μm Turkey vs. 29.46μm Switzerland). This karyological difference is not considered to be the result of the presence of B chromosomes, but probably the result of hybridization between different genotypes. Aborted seed pods were observed which lent credibility to this hypothesis. Plants of this accession may have arisen as a result of hybridization between Lotus corniculatus and/or L. alpinus as both diploid and tetraploid cytotypes are reported in the Turkey collection for these species. The data would lend support for their hybrid origin.     

Ephemeral and non-ephemeral structures during seed development in two Cytisus species (Papilionoideae,Leguminosae)

Abstract

Seed formation involves not only the embryo and endosperm development, but also the formation of a series of either ephemeral or non-ephemeral structures. In this article, we study several of those structures in Cytisus multiflorus and Cytisus striatus. The endosperm development is first nuclear and later cellular, except for the chalazal area, whose development is always nuclear. It generates, in the early developmental stages, a sac-like haustorium. As the seed develops, two structures seem to be closely related to nutrient mobilization to the embryo sac: on the one hand, a group of cells and a channel, located in the chalazal area and closely related between them and to the endosperm haustorium, which could be interpreted as a hypostase and on the other hand, an endothelium, derived from the inner integument, which later degenerates leaving no trace in the mature seed. All of these structures would be associated with the directionality of assimilates from ovule tissues to embryo sac. In mature seed and surrounding the embryo appears a unicellular layer of cells rich in proteins (aleurone layer), which is the origin of the outermost layer of the cellular endosperm. The seed coat is made up only of the outer integument.