Seeds of Papilionoideae (Leguminosae) species lose water after dispersal, increasing the proportion of water-impermeable seeds (physical dormancy, PY). However, changes in testa structure during this process remain unknown. The present study investigated how variation in relative humidity (RH) during the post-dispersion period affects the proportion of seeds of Erythrina speciosa with PY. Seeds from two populations were stored in drier (40% RH) and wetter (80% RH) environments and periodically subjected to physiological analysis (seed water content, imbibition and germination) and structural analysis of the testa (light and scanning electron microscopy). Drier storage resulted in seed dehydration, increasing the proportion of water-impermeable seeds and closure of cracks in the mucilaginous stratum. In contrast, wetter storage led to an increase in seed water content, a decrease in the proportion of seeds with PY, and the formation of cracks. As a result of variation in environmental humidity, we conclude that changes occur in the mucilaginous stratum of seeds, altering water loss and, consequently, the proportion of seeds with PY. Environments with low humidity cause a decrease in seed water content, the closing of cracks in the mucilaginous stratum, and, consequently, an increase in the proportion of water-impermeable seeds. On the other hand, a high RH environment increases the seed water content and the formation of superficial cracks, through which water enters during imbibition, causing a decrease in the proportion of seeds with PY.

Catclaw mimosa, an exotic member of the Leguminosae, occurs in three areas of Florida. Propagation is by seed only. Seeds collected from Florida were used for germination, growth, and herbicide evaluation studies. Seeds germinated at 75 to 94% but were not influenced by different environmental conditions under which they were stored. Greenhouse-grown plants cut or burned off at ground level failed to regrow. However, plants cut at 2 cm or more above ground level regrew from lateral shoots. Sixteen herbicides were evaluated to determine their effects on 6- to 8-wk-old plants grown in the greenhouse. Catclaw mimosa was killed by picloram, tebuthiuron, hexazinone and sulfometuron at 0.4, 0.07, 0.14, and 0.56 kg ha-1, respectively. Dicamba at 1.12, triclopyr at 1.12 (Garlon 3A and 4), linuron at 4.48, and glyphosate at 8.96 kg ha-1 were also effective. Chlorsulfuron and metsulfuron killed 9 out of 10 plants at the highest rates tested. Four herbicides, imazapyr, thifensulfuron, DPX-L5300, and atrazine killed 50% or less of the plants at the highest rates of each compound tested. Fosamine did not kill catclaw mimosa at the rates tested.

The Pleistocene Arc Theory (PAT) suggests that present-day disjunct fragments of dry forests in central tropical South America give evidence of a previously more continuous distribution during the Pleistocene that has been disrupted by dry-cold vs. humid-warm climatic cycles. This Arc extends from NE Brazil to NE Argentina and eastern Paraguay, through the Chiquitanía to NW Argentina and SW Bolivia and into the dry inter-Andean valleys in Peru and Ecuador, with intrusions into the Great Chaco. Seasonally Dry Tropical Forests (SDTFs) are floristically and physiognomically dominated by woody legumes, mostly deciduous in the dry season. In the last two decades field collection and research on legume taxa has greatly increased, with a significant number of taxonomic revisions and molecular phylogenetic studies, together with some paleoclimatic modelling studies. The evidence accumulated in the last 23 years has confirmed the integrity of the Chaco and Caatingas phytogeographical provinces, with an impressive and increasing level of botanical endemism discovered. The PAT pattern has also been supported, specifically through the mapping of five selected woody Leguminosae species (Anadenanthera colubrina, Enterolobium contortisiliquum, Pterogyne nitens, Amburana cearensis and Piptadenia viridiflora). The pre-existing nuclei of South American SDTF (Caatingas, Misiones and Piedmont) are now increased to four with the postulation of the Chiquitanía Nucleus in south-eastern Bolivia and bordering Paraguay. Some new endemisms are compiled from recent literature and mapped for the Misiones and Chiquitanía nuclei. The need for more botanical collections and further taxonomic, phylogenetic and demographic studies of South American legumes is emphasised.

Life table studies were conducted on the flowers, pods and seeds of the tree Pithecellobium pallens to assess the extent of damage by the seed predators Stator limbatus and Merobruchus insolitus (Coleoptera: Bruchidae). Brachyacma palpigera (Lepidoptera: Gelechiidae) was also found to feed on the seeds of this tree. Seed predation and herbivore damage destroyed 41% of the seeds. Pods were taken to the laboratory and seed predators within were reared and identified. B. palpigera and M. insolitus were major causes of mortality, whereas damage by S. limbatus was slight. The growth ratio of pods to seeds did not indicate a rapid development of seeds as an evasive strategy against bruchid attack. Experiments showed no successful attack by bruchids on seeds exposed on the ground after dispersal from the tree.

The demographic history of a flower-cohort of the tropical tree Dicymbe altsonii (Caesalpiniaceae) was studied by collecting litter from flowers, fruits and seeds, and by monitoring seedling survival. Flower production was estimated at 137 to 172 m−2 in a plot of 1 ha. Four percent of the flowers yielded a pod, which contained an average of 2.0 seeds. Post-dispersal mortality over 3 mo was 39% of the initial number of dispersed seeds. Most flowers and fruits were aborted. Insect and vertebrate predation in the tree and on the ground was very low. Reproductive litter production of this species was estimated to be equal to leaf litter production. The amount of phosphorus lost in litter from fruits and flowers was much larger than in leaf litter. This implies that the impact of the biennial flowering events on the nutrient dynamics of the trees and of the ecosystem may be large. It is argued that the reproductive cycle and the pre-dispersal demography of Dicymbe seem to be determined by a scarcity of nutrient resources, and possibly by pollinator limitation.

The new species Baphia megaphylla Breteler (Leguminosae – Papilionoideae) from Gabon is described and illustrated. It is most closely related to Baphia maxima Baker. The differences between the two species are summarised in a key.

Biological N fixation by symbiotic micro-organisms plays a key role in making atmospheric N largely available to other organisms and nodule formation by rhizobia in roots of many legume species represents a very important pathway (Postgate 1998). Estimates of the contribution of symbiotic fixation to total N content in soils range from 44 to 200 Tg y−1 (Bøckman 1997).

Some physiological characteristics of ACC-Nmalonyltransferase (ACC-N-MTase) have been studied in the seeds of chick-pea (Cicer arietinum L.). This enzymatic activity was detectable during all periods of zygotic embryogenesis; however, the highest values were found in the dry seed. In dry seeds, the enzymatic activity was greater in the embryonic axis than in the cotyledons. During the onset of germination, activity increased more strongly in the cotyledons than in the embryonic axis, reaching its highest values in the storage organs coinciding with radicle emergence (18 to 24 h). Removal of the cotyledons strongly diminished enzymatic activity in the embryonic axis. Low concentrations of ethrel (50 µM) stimulated the axis ACC-N-MTase. The highest specific activity was found in the apical meristem of the embryonic axis, declining over the length of the organ. The role of ACC-N-MTase activity in the germinative process is discussed, together with the regulatory effect of ethylene on this ACCconjugating enzyme.

A recombinant protein (approximately 38 kDa by SDS/PAGE), induced by expression in Escherichia coli of a cDNA encoding a 1-aminocyclopropane-1-carboxylate oxidase (ACO) isolated from embryonic axes of Cicer arietinum, was recognized by an antibody raised against an apple ACO. A monoclonal antibody, obtained from recombinant ACO of chick-peas, was used for immunolocalization experiments in the embryonic axes of chick-pea seeds. The results indicate that most of the ACO was present in the apoplast of the cell wall. No evidence of this protein in the vacuole was detected. During germination of C. arietinum seeds, the production of ethylene was induced in the embryonic axis; its highest value was reached when radicle emergence occurred. At this moment there was an accumulation of 1-aminocyclopropane-1-carboxylate (ACC), transcription of ACO mRNA, as well as maximal ACO activity. In the post-germinative period the activity of the last step of ethylene biosynthesis decreased. This decrease was eliminated by indole-3-acetic acid (IAA), which caused significant transcription of ACO mRNA. It is suggested that gene expression of ACO may be induced by auxins and spermine (Spm) and inhibited by abscisic acid (ABA).

Berlinia Sol. ex Hook.f. (Leguminosae – Caesalpinioideae) is under investigation with two main goals: (i) to delimit and describe the species, and (ii) to elucidate their relationships. Delimitation and description is now largely completed and is presented in this synopsis. The genus Berlinia is assessed as comprising 18 species. Keys to the species are presented and for each species a brief description, selected synonymy and specimen citations are given. A monograph of Berlinia including a full taxonomic treatment and the results of the phylogenetic investigation will be published later by the senior author.

Two new species of Ormosia (Leguminosae – Papilionoideae, Sophoreae) are described: Ormosia carinata N.Zamora and Ormosia intermedia N.Zamora.

Locus-specific primers were designed to amplify the homologues LEGCYC1A and LEGCYC1B of the snapdragon (Antirrhinum majus) floral symmetry gene CYCLOIDEA in the genistoid legumes Lupinus nanus and Cadia purpurea. These primers were tested successfully in a range of genistoid taxa. Sequence comparison between L. nanus and L. angustifolius revealed that these CYCLOIDEA-like genes provide up to four times as many variable characters as the ribosomal internal transcribed spacers (ITS) at this taxonomic level. These genes are therefore potentially useful for studying evolutionary relationships between closely related species within the genistoid clade of legumes, which contains many large and diverse genera. Comparisons between L. nanus, Cadia purpurea and Calpurnia aurea LEGCYC sequences show that these genes may also be useful for phylogenetic studies between genera in this large clade of 1800 species.

Canopy observations of the rain forest tree Parkia velutina (Leguminosae: Mimosoideae) in Amazonian Brazil indicate that it is pollinated by night-flying bees. The small red flowers are organized into spherical heads; they open in the late afternoon and attract Megalopta bees (Halictidae: Augochlorini) which forage for pollen after dark. In contrast to the numerous bat-pollinated species of Parkia, no nectar was detected. Nocturnal melittophily is proposed as a possible intermediate stage in the evolution of chiropterophily from diurnal entomophily in Parkia.

Hylodesmum H. Ohashi & R.R. Mill (Leguminosae or Fabaceae, tribe Desmodieae), based on Desmodium sect. Podocarpium Benth. (=D. subgen. Podocarpium (Benth.) H. Ohashi), is a replacement name proposed here for Podocarpium (Benth.) Y.C. Yang & P.H. Huang published in 1979 for Chinese species belonging to the genus. The name it replaces, Podocarpium (Benth.) Y.C. Yang & P.H. Huang, is a later homonym of two earlier names, Podocarpium A. Braun ex Stizenb. (fossil Leguminosae or Fabaceae) and Podocarpium Unger (fossil Podocarpaceae) and it is also inadmissible under Art. 20.2. New combinations in Hylodesmum are proposed for 14 species and nine infraspecific taxa. A description of the genus is given as well as brief notes on the distribution of each taxon. Shuteria longipes Franch. and Desmodium duclouxii Pamp. are newly regarded as conspecific; the correct name for these in Hylodesmum is H. longipes. Notes on typification are given for several names.

Dussia atropurpurea is a new species found in Costa Rica and Panamá. It differs from all other Dussia species in this region in its dark purple sarcotesta. The only other species of Dussia with a sarcotesta of this colour is the Amazonian D. tessmannii which is clearly distinct morphologically. Sarcotesta colour is an important character for species delimitation in Dussia, but is infrequently recorded.

Leafing, flowering and fruiting of the 24 most representative species of trees and shrubs in Sudanian savannas and fallows near Bondoukuy (Burkina Faso) were studied for 2 y (May 1992 to June 1994). The period of defoliation was generally brief, and leaf flushing, flowering and fruiting occurred mostly in the dry season. The phenological behaviour varied nonetheless across species and individuals. A classification taking into account synchrony/asynchrony and duration in foliation, flowering, fruit ripening and seed dispersal phases allowed comparison of species' phenological plasticity. Species were distributed along a scale of increasing plasticity, from trees to shrubs. Along this scale, species of the Leguminosae appeared to be separated from those of the Combretaceae, the latter being generally considered as characterising fallow farming systems. These results provide new evidence about the effect of phylogenetic constraints on the phenological behaviour of the woody species of the Sudanian savannas.

RÉSUMÉ. La feuillaison, la floraison et la fructification des 24 espèces d'arbres et d'arbustes les plus représentatives des jachères et savanes soudaniennes de la région de Bondoukuy (Burkina Faso), ont été étudiées pendant 2 ans (mai 1992 à juin 1994). La défeuillaison est généralement brève et l'émergence des feuilles, la floraison et la fructification se produisent principalement pendant la saison sèche. Les comportements phénologiques varient cependant entre les individus et entre les espèces. Une classification prenant en compte le degré de synchronisme ainsi que la durée de la feuillaison, de la floraison, de la maturation des fruits et de la dispersion des graines a permis de comparer la plasticité phénologique des espèces. Celles-ci sont distribuées selon un gradient de plasticité croissante des arbres aux arbustes. Sur ce gradient les Légumineuses se dissocient des Combrétacées, espèces qui sont par ailleurs généralement considérées comme caractéristiques des jachères. Ces résultats sont une nouvelle illustration de l'effet des contraintes phylogénétiques sur le comportement phénologique des espèces ligneuses des savanes soudaniennes.

A new 6a-hydroxylated pterocarpan, named hildecarpin, has been isolated from the healthy roots of Tephrosia hildebrandtii. It has been assigned the structure (−)-3, 6a-dihydroxy-2-methoxy-8, 9-methylenedioxypterocarpan on the basis of its spectroscopie data, optical rotation and chemical transformations. Hildecarpin has exhibited insect antifeedant activity against the legume pod-borer Maruca testulalis, an important pest of the cowpea (Vigna unguiculata), and antifungal activity against Cladosporium cucumerinum. This finding suggests that the pterocarpan phytoalexins formed as a result of microbial infection of the cowpea plant may constitute a basis for induced resistance in the plant against M. testulalis.