Sesbania Species Research Articles

Insects feeding on Sesbania species in natural stands and agroforestry systems in southern Malawi

Pest and disease interactions in agroforestry systemsis a little studied area.Surveys were conducted in the Mangochi and Zomba districts of southern Malawi between December 1997 and February 1998 to identify insects feeding on Sesbania species in natural stands and in agroforestry systems at the research station and on farms, and the host range of the insects. Out of a total of 30 insect species recorded in natural stands, Brachyplatys testudonigro, Mesoplatys ochroptera, Exosoma sp. and Ootheca sp. were the most commonly found insects feeding on S. sesban. Afrius figuratus, Glypsus conspicuus, Macrorhaphis acuta, Mecosoma mensor, Rhinocoris segmentarius and Cyaneodinodes faciger were recorded for the first time as natural enemies of Mesoplatys ochroptera in Malawi. The defoliating beetles, M. ochroptera, Exosoma sp. and Ootheca sp., were the most frequently found insects infesting S. sesban on farms. M. ochroptera attacked only Sesbania species, and usually higher populations of this beetle were recorded on annual Sesbania species (S. tetraptera, S. bispinosa, S. leptocarpa and S. sericea) than on perennial types. Although the sap-sucking bug, B. testudonigro, was relatively less common on sesbania on farms, it has been found to infest a number of other legumes of the genera Aeschynomene, Crotalaria, Desmodium, Indigofera, Mucuna, Phaseolus, Tephrosia and Vigna. Given the wide variety of plant species it attacks, B. testudonigro may become a potential pest of many agroforestry tree species. The insects Anoplocnemis curvipes, Aphis fabae, Hilda patruelis, Megaleurothrips sjostedti, Mylabris dicincta, Nezara viridula and Ootheca sp. also have the potential to become pests of agroforestry systems, as they can damage many agroforestry trees, including Sesbania, and crops. There is a need to study the biology and ecology of potential insect pests of S. sesban to plan for their integrated management in agroforestry.

Morphological and agronomical characterization and estimates of genetic parameters of sesbania Scop. (Leguminosae) accessions

Twenty-two accessions of seven Sesbania (Leguminosae) species: S. emerus, S. rostrata, S. tetraptera, S. exasperata (annuals), S. grandiflora, S. sesban and S. virgata (perennials), used for ruminant fodder, firewood, wood products, soil improvement, and human food, were investigated, with the aim of characterizing both inter- and intraspecific genetic variability, estimating genetic parameters for the characters evaluated and appraising the forage potential of the accessions. These were planted at the Instituto de Zootecnia, Nova Odessa, SP, Brazil, in a randomized complete block design with 22 treatments and four replications. Seventeen morphological and 17 agronomic characters were evaluated. Genetic parameters coefficient of intraspecific genetic diversity (bi) and coefficient of intraspecific genetic variation (CVgi) were obtained for the species represented by more than one accession. Highly significant differences were observed among as well as within species for most characters, showing considerable genetic variability. S. exasperata showed intraspecific genetic variability for the largest number of morphological characters. The same was observed for S. sesban for the agronomic characters. Most of the characters gave high bi values, above 0.80, indicating the possibility of selecting superior genotypes. The CVgi values, on the other hand, which indicate the magnitude of the existing genetic variability relative to the character mean, varied according to the species and character evaluated. Differences between annual and perennial species were observed, with higher biomass yields presented by the annuals at the first cut and by the perennials after the second cut, reaching the highest yield at the third cut. The annual species had higher seed production. Accession NO 934 of S. sesban gave the highest biomass yields and regrowth vigor, showing promise as a forage legume plant.

Longitudinal differentiation in chromosomes of someSesbaniaScop, species (Fabaceae)

Abstract Three different techniques were applied to analyze the patterns of longitudinal chromosome differentiation in five Sesbania species (S. exasperata, S. punicea, S. sesban, S. tetraptera, and two different geographical populations of S. virgata). For all the species investigated, the prophase chromosome condensation was always proximal. After staining with the fluorochromes chromomycin A, and DAPI, each karyotype revealed two or four CM AY DAPI∼ heterochromatic blocks, apparently corresponding to the nucleolus organizing regions. However, in S. virgata two or four CMA+ bands were observed, depending on the population studied. No DAPI+ bands were observed. C-banding showed the most diversified patterns, being a more useful technique to distinguish karyorypes of Sesbania species. The largest amount of heterochromatin was observed in S. virgata (subgenus Daubentonia) whereas the smallest was found in S. sesban (subgenus Sesbania).

Rapid deployment of allelochemicals in exudates of germinating seeds of Sesbania (Fabaceae): roles of seed anatomy and histolocalization of polyphenolic compounds in anti-pathogen defense of seedlings

We determined the localization of phenolic compounds in dormant seeds of two American species of Sesbania (Fabaceae) by a combination of histochemical and biochemical methods. Phenolics are located in different layers of the seed coat and in the subhilar parenchyma. We then investigated the release of these compounds by imbibing seeds of both species. The annual S. vesicaria releases the flavonoid luteolin, with minor amounts of proanthocyanidins, whereas the perennial S. drummondii releases mostly proanthocyanidins. Types and amount of allelochemicals exuded seem related to ecology and life history traits of each species. We then showed mobilisation of these allelochemicals by histochemical sections in imbibing seeds of both species. Histological structure is similar in both species. A number of characters (lens, subhilar parenchyma, tracheid bar) appear to function together to facilitate the exudation of compounds that protect young seedlings. Furthermore, the spatial organization of these organs with interlocking function allows retrieval of defensive substances stored in the seed, and their redeployment is beneficial for seedling survival. We hypothesize that optimisation of the chemical defences allocated to the seed by the maternal parent confers a significant advantage to the seedling, whose energy is mainly committed to growth.

Sesbania melanocaulis, sp. nov. (Leguminosae subfam. Papilionoideae) from SW. Ethiopia

Sesbania melanocaulis Bidgood & Friis sp. nov., is described from a mosaic of humid montane forest, forest margins, evergreen bushland and farmland in the Kefa and Welega Regions of SW. Ethiopia. The new species is a very distinctive small tree which is also widely used as a hedge plant throughout SW. Ethiopia. It belongs to subgen. Sesbania and resembles the widespread Sesbania sesban from which it differs most conspicuously in the dark purplish brown to almost black bark of the stems which are pilose to pubescent when young, the large pale tomentose stipules and the uniformly yellow flowers (dark dotted in S. sesban). The importance of SW. Ethiopia as a local centre of endemism has been confirmed by several recent studies, including preparatory work for the Flora of Ethiopia and Eritrea. The new species of Sesbania is only one of several leguminous trees which have been taken into domestication in Ethiopia.

Mineralization of N, P, K, Ca and Mg from Sesbania and Leucaena leaves varying in chemical composition

The N, P, K, Ca and Mg release patterns of the leaves of four accessions of Sesbania species and two accessions of Leucaena species were evaluated in a 5-week laboratory incubation. Leaves of these leguminous trees, applied at an equivalent rate of 3 t dm ha −1, were significant sources of N, K and Mg, but insignificant sources of P and Ca relative to the soil (control). Nitrogen in sesbania leaves was mineralized more rapidly than that in leucaena leaves; one sesbania accession released as much N as that released from urea fertilizer applied at an equivalent rate of 60 kg N ha −1. Mineralizable N ranged from 15 to 53% of leaf N and it was negatively correlated with hemicellulose content and hemicellulose-to-N ratio. The results indicate that additional N and P may be required if these leaves are used as sources of nutrients for crops. In acid soils low in Ca, additional Ca may also be required.

Karyological Studies in Some African Species of the Genus Sesbania (Fabaceae).

Karyological criteria of 15 African species of Sesbania, including five new records, are presented. A diploid number of 2n =12 (x=6) has been found in 12 species, 2n =14 (x=7) in onespecies and a tetraploid number of 2n =4x=24 was recorded in S. formosa and S. grandiflora. The karyotype in the examined species is symmetric. However, considerable variation exists in chromo-some size among the species studied.The result of the present study confirm that x=6 may be considered the basic number in the genus. Our observations further indicate that Sesbania is a primitive genus in its tribe Robinieae from which other genera may have evolved through aneuploid and polyploid changes.

Suitability of the North American Weeds Sesbania exaltata and S. drummondii (Leguminosae) as Hosts for Neodiplogrammus quadrivittatus and Trichapion lativentre (Coleoptera: Curculionidae) in Argentina

Neodiplogrammus quadrivittatus (Oliver) and Trichapion lativentre (Beguin-Billecocq) are 2 South American weevils successfully used for the biological control of Sesbania punicea (Cavanille) Benth. in South Africa. The potential of these insects as control agents for the weeds Sesbania exaltata (Raf.) Rydb. and S. drummondii (Rydb.) Cory in the United States was studied in Argentina. Estimation of adult consumption, the food preference of adult insects on 5 species of Sesbania (3 native hosts and the 2 weeds mentioned above), the capacity of the insects to complete their life cycle on the weeds, and the weed infestation by wild populations in the laboratory garden were studied. The consumption of N. quadrivitattus on both north American weeds did not differ from that on native hosts. Similar consumption was observed for T. lativentre feeding on S. drummondii. S. exaltata showed the lowest consumption. The feeding preference of N. quadrivittatus was similar to that of its natural host plants. In the case of T. lativentre, results on only S. drummondii were comparable to that of its natural hosts. Both insects were able to complete their life cycles on the weeds. In the garden, there was a marked preference by the weevils for S. drummondii. S. exaltata was not attacked by T. lativentre and no test was carried out with N. quadrivittatus. We concluded that both insects are good biocontrol candidates for S. drummondii, whereas only N. quadrivittatus is a promising control agent for S. exaltata.

The Sesbania Root Symbionts Sinorhizobium saheli and S. teranga bv. sesbaniae Can Form Stem Nodules on Sesbania rostrata, although They Are Less Adapted to Stem Nodulation than Azorhizobium caulinodans

Sesbania species can establish symbiotic interactions with rhizobia from two taxonomically distant genera, including the Sesbania rostrata stem-nodulating Azorhizobium sp. and Azorhizobium caulinodans and the newly described Sinorhizobium saheli and Sinorhizobium teranga bv. sesbaniae, isolated from the roots of various Sesbania species. A collection of strains from both groups were analyzed for their symbiotic properties with different Sesbania species. S. saheli and S. teranga bv. sesbaniae strains were found to effectively stem nodulate Sesbania rostrata, showing that stem nodulation is not restricted to Azorhizobium. Sinorhizobia and azorhizobia, however, exhibited clear differences in other aspects of symbiosis. Unlike Azorhizobium, S. teranga bv. sesbaniae and S. saheli did not induce effective stem nodules on plants previously inoculated on the roots, although stem nodulation was arrested at different stages. For Sesbania rostrata root nodulation, Sinorhizobium appeared more sensitive than Azorhizobium to the presence of combined nitrogen. S. saheli and S. teranga bv. sesbaniae were effective symbionts with all Sesbania species tested, while Azorhizobium strains fixed nitrogen only in symbiosis with Sesbania rostrata. In a simple screening test, S. saheli and S. teranga bv. sesbaniae were incapable of asymbiotic nitrogenase activity. Thus, Azorhizobium can easily be distinguished from Sinorhizobium among Sesbania symbionts on the basis of symbiotic and free-living nitrogen fixation. The ability of Azorhizobium to overcome the systemic plant control appears to be a stem adaptation function. This last property, together with its host-specific symbiotic nitrogen fixation, makes Azorhizobium highly specialized for stem nodulation of the aquatic legume Sesbania rostrata.

Sesbania species as potential hosts to root-knot nematode (Meloidogyne javanica) in Tanzania

In two glasshouse studiesSesbania accessions were compared with a susceptible tomato cultivar as hosts toMeloidogyne javanica. Inoculating the growth medium with either infective juveniles or egg masses resulted in significant differences in root galling and egg mass production. The accessions could be grouped into moderate and poor hosts. Growth of roots was also depressed by the infestation. In a field study on a nematode infested site, significant variation in root galling was observed. Infestation was lower in plants growing on ridges than those on flat land. The studies indicate that continued cultivation ofSesbania may lead to a build up in soil root-knot nematode populations.

Nitrogen fixation response of stem- and root-nodulating Sesbania species to flooding and mineral nitrogen

The flood adapted green manure legumes Sesbania cannabina and S. rostrata differ in their nodulation, the former nodulating on root only but the latter on both root and aerial stem. In the early wet season pre-rice niche in lowlands, these legumes are exposed to varying soil aeration and N status with NO3- as the main N source in aerobic and NH4+ in flooded soil. To better use these legumes, the influence of soil aeration status and the resulting differences in soil N supply on N assimilation characteristics and biological nitrogen fixation (BNF) must be understood. We examined the interactions among soil aeration status, supply and form of mineral N, and BNF (estimated by 15N dilution) by growing S. rostrata and S. cannabina for 40 days in aerobic or flooded potted soil (3 kg) with zero to 3000 mg applied N. Both NH4+ and NO3- were used in aerobic soil but only NH4+ in flooded soil. In aerobic soil, N accumulation potential of S. rostrata and S. cannabina were similar with NO3-, NH4+, or BNF as the major N source. Soil flooding increased N accumulation, but consistently more by S. rostrata than by S. cannabina. The maximum N accumulation of 275 mg plant-1 by S. rostrata was 20% greater than the maximum N accumulation by S. cannabina, in flooded soil, and 80% greater than maximum N accumulation by both legumes in aerobic soil. Regardless of soil aeration status and nodule location, mineral N increasingly substituted for biologically fixed N until total replacement occurred at non-limiting N supply. Reduction in the amount of BNF due to applied mineral N was greater in aerobic soil (with NO3- as the N source) than in flooded soil (with NH4+ as the N source) for both legumes. Compared to root nodules, stem nodule BNF activity was less sensitive to NH4+ in flooded soils and resulted in more BNF-N in S. rostrata. Higher N requirement, stem-nodulation, and probably an ammoniphyllic character, allow S. rostrata to accumulate more N than S. cannabina in flooded soils.

Differential acidity tolerance of tropical legumes grown for green manure in acid sulfate soils

The growth of four tropical legumes (Cajanus cajan, Sesbania aculeata, S. rostrata, and S. speciosa) used as green manures in the tropics was studied in a glasshouse experiment. Two acid sulfate soils (Typic Sulfaquept, Bang Pakong Series; and Sulfic Tropaquept, Rangsit Series) were adjusted to four pH levels: 3.8 or 4.0 (original soil pH), 4.5, 5.5, and 6.5 (amended with lime). Dry weight was determined 49 days after sowing. Concentrations of N, P, K, Ca, Mg, Fe, Mn, and Al were also determined in aerial plant parts at harvest. The legumes responded differently to soil acidity and liming, but not to soil type. Cajanus cajan had the highest biomass production, followed by S. aculeata, S. rostrata and S. speciosa, in this order. The N concentration closely paralleled biomass production, suggesting that the growth of symbiotic rhizobia and nodulation were perhaps more susceptible to soil acidity than were the host plants. Liming to pH 5.5–6.0 was recommended for the legumes' growth based on the quadratic relationships between dry-matter yield and soil pH. In the unlimed soils, the Ca concentration in C. cajan and S. aculeata (0.32%) was twice as high as that in the two low-yielding legumes (0.15%). Furthermore, plant Ca increased exponentially (or quadratically in case of S. speciosa) as lime additions increased. It was estimated that for adequate growth, the Ca requirement in the shoot dry matter was approximately: C. cajan 1.2% Ca, S. aculeata 0.8%, S. rostrata 0.6%, and S. speciosa 0.4%. In contrast with Ca, the concentration of Fe, and to a lesser extent Mn, was significantly lower in C. cajan and S. aculeata than in S. rostrata and S. speciosa. The ratio of Ca to Al in plant tops was used to characterize plant tolerance to soil acidity, and to quantify the critical Al concentration in the plants. It appears that ≥ 90% maximum growth was attained only when Ca/Al was ≥ 150 for C. cajan and S. speciosa, ≥ 200 for S. rostrata, and ≥ 300 for S. aculeata. Cajanus cajan tolerated up to 80 mg Al kg-1 in the shoot dry matter, whereas significant growth reduction occurred in the Sesbania species at levels > 30 mg Al kg-1.

The relationships between gas production and chemical composition of 23 browses of the genus Sesbania

AbstractThis study evaluated the differences in the gas produced by Sesbania accessions and related gas production to macro‐constituents and tannin content of the browse species. Fresh samples were incubated in triplicate (about 200 mg per syringe) in a medium prepared from sieved rumen liquor harvested from two rumen‐fistuiated cows fed native pasture hay ad libitum and 2.0 kg cottonseed cake per head per day. Sesbania species had similar rates of gas production but differed (P < 0.001) in the volume of gas produced. The ranking order for gas production was S grandiflora > S sesban > S keniensis > S goetzei. There was little variation in the gas production parameters within S grandiflora and S goetzei. But the variation was large within S sesban. Regression analysis showed that the rate of gas production was negatively affected (P < 0.025) by the lignin content of the browses, but the volume of gas produced was negatively related to the neutral detergent fibre, hemicellulose, lignin and insoluble proanthocyanidins content of browses. Ouster analysis showed a broad agreement between gas production constants, macro‐constituents and tannin contents in classifying accessions into high or low nutritive value groups.

Performance of multipurpose tree and shrub species 28 months after planting at Chalimbana, Zambia

Sixteen multipurpose tree and shrub species (MPTs) for agroforestry were planted in a screening trial at Chalimbana near Lusaka, Zambia in December 1987. The trial was at 1280 m altitude on a sandy loam belonging to the luvisol-pharzem soil group, under unimodal rainfall (mean 880 mm). One year after planting all the 16 species except Sesbania grandiflora showed excellent survival. Sesbania sesban, Eucalyptus camaldulensis, Eucalyptus grandis, Leucaena leucocephala, Cassia siamea, Flemingia congesta and Acacia polyacantha var. compylacantha grew fast with high volume and biomass production. An assessment made 28 months after planting showed these species to be 3.5–6.8 m in height, 8.0–14.3 cm basal diameter, 10–57 m 3 ha −1 standing volume and 19.0–57.7 tons ha −1 above ground biomass (dry weight basis). Sesbania species had short life-spans (1 year for Sesbania macrantha and 2.5 years for Sesbania sesban) but had outstanding growth and biomass production. This makes them ideal candidate MPTs for improved fallows, enrichment of fodder banks and green manure production. L. leucocephala, Cassia siamea and F. congesta have potential for testing in alley cropping, rotational fallows and other technologies while Acacia polyacantha can be tested in mixed intercropping. Acacia albida, Acacia ataxacantha, Afzelia quanzensis, Sterculia africanum, Albizia adianthifolia, Casuarina cunninghamiana and Ventilago viminalis showed slow growth.

Screening of multipurpose tree and shrub species for agroforestry in the humid lowlands of Cameroon

A field screening trial of ten exotic multipurpose trees and shrubs was initiated in August 1987 in Yaounde, Cameroon. The objective of the study was to identify adaptable species with desirable traits that could be used for agroforestry systems recommended for the humid lowlands of Cameroon. The species included were Acacia auriculiformis, Acacia mangium, Calliandra calothyrus, Cassia javanica, Cassiaa siamea, Gliricidia sepium, Leucaena leucocephala, Paraserianthes falcataria, Sesbania grandiflora and Sesbania sesban. Results suggested that the two Sesbania species were poorly adapted to the region (based on survival rate). P. falcataria and Calliandra calothyrsus were among the fastest growing species and their foliage had high nutrient values, making them promising candidates for agroforestry technologies aimed at improving soil fertility. However, the coppicing ability of P. falcataria was below average. Primary growth of the Acacia species was relatively high, but they were poor coppicers. They could be useful as shade trees on cocoa or coffee farms, but are not suitable for hedgerow intercropping.

Karyotypes of Species of Sesbania Scop.(Fabaceae).

The karyotypes of five species of Sesbania were studied. All species had 2n=12 and there was agreement with x=6 for the genus. The majority of chromosomes were metacentric and their length varied from 2.12 to 6.99μm. Karyotype information is presented for the first time for three species. There are correlations between karyotypes and taxonomic arrangement at subgenus level. Some phylogenetic relationships were discussed. Comparisons of TF% index agreed with the proposals presented in literature.

Plant regeneration from callus and explants of Sesbania spp.

Root, hypocotyl and cotyledon explants of Sesbania bispinosa, Sesbania cannabina, Sesbania formosa, and Sesbania sesban were cultured on Murashige and Skoog medium with benzyladenine (BA; 2.22, 4.44, 8.88 μM) in combination with 2,4-dichlorophenoxyacetic acid (2,4-d; 2.26, 4.52, 9.05 μM), indolebutyric acid (IBA; 0.25, 0.49, 4.92 μM) or naphthaleneacetic acid (NAA; 2.69, 5.37, 10.74 μM). Although all explant types developed some callus, callus occurred earliest and continued to grow fastest with hypocotyls. Media including 2.4-d or NAA gave the fastest growing callus. Callus was subcultured up to 10 times at 20-day intervals and retained a rapid growth rate. Shoots regenerated readily from both hypocotyls or cotyledons but not from roots. Shoot organogenesis was most frequent with IBA (0.25–4.92 μM) in combination with BA (4.44–8.88 μM) and did not occur with 2,4-d. With each species at least one medium induced shoot differentiation from more than 50 percent of the callus pieces. With one exception, media containing IBA that induced shoot organogenesis on explants also did so in callus, but media containing NAA, even when effective with explants, did not cause differentiation of callus. Shoots that differentiated were excised and cultured on MS medium without growth regulators or with IBA (2.46, 4.92, 9.84 μM). Roots developed after 3–8 days on an appropriate rooting medium, often without IBA. Rooted plantlets were transplanted to pots in a greenhouse and developed into normal plants. Suitable media and protocols for initiating and subculturing callus and regenerating whole plants in vitro from callus and explants have thus been established for four species of Sesbania.

Karyological Studies in the Genus Sesbania.

Detailed somatic karyotype analysis was carried out in 6 species of Sesbania. Of these, four species namely aculeata, rostrata, aegyptica and speciosa were diploid with 2n=12 chromosomes, while the species grandiflora was a tetraploid with 2n=24 chromosomes. The other species, sesban has both diploid (2n=12) and tetraploid (2n=24) cytotypes. Considerable differences were observed among the different species in terms of total chromatin length and volume with the values ranging from as high as 47.07μm and 31.98μm3 in S. qrandiflora to as low as 18.31μm and 8.98μm3 in the species S. aegyptica. All diploid cytotypes except aculeata, exhibited one pair of SAT-chromosomes each, usually the second longest in the complement. In tetraploid forms two pairs of chromosomes (chro. 1, 2) carried secondary constriction in their long arms. The karyotypes of all species except aculeata were found to be symmetric with predominanty metacentric chromosomes. S. aculeata, however, had an asymmetric karyotype with 2 pairs of sub-metacentric and 1 pair of sub-telocentric chromosomes in addition to 3 metacentric pairs. Relative lengths, S% and TF% estimations also support the above view. The occurence of diploid and tetraploid forms in S. aculeata and S. sesban suggests the possibility of the existence of tetraploid forms in other Sesbania species also.

Nitrogen fixation, biomass production, and nutrient uptake by annual Sesbania species in an alkaline soil

In three field trials conducted during the summer season of 1986, 1987 and 1989 in an alkaline soil, 17 accessions of annual Sesbania spp. were evaluated for nodulation, N2 fixation (acetylene reduction assay), dry weight of roots and shoots, woody biomass production, and nutrient uptake. At 50 days after sowing all the accessions were effectively nodulated (average 36.4 root nodules plant-1) with a high nodule score (3.4). There was a lot of variation in nodule volume and mass and in acetylene reduction activity but not in N content (5.2%). N uptake in shoots, roots and nodules averaged 639, 31, and 13 mg plant-1, respectively, and much of the fixed N remained in shoots. Accessions of ‘S. cannabina’ complex performed better than others. S. rostrata had poor root nodulation but exhibited excellent stem nodulation (300 nodules plant-1) even though not inoculated with Azorhizobium sp. Average concentrations of N, P, K, S, Ca, and Mg in the shoots were high, at 3.2, 0.28, 1.5, 0.28, 1.5, and 0.4% respectively, and Na was low (0.15%), reflecting the usefulness of Sesbania spp. as an integrated biofertilizer source. Green matter production was 26.0 Mg ha-1 (5.9 Mg dry matter) and N uptake was 158 kg ha-1, 54 days after sowing. Average woody biomass of six accessions at maturity, 200 days after sowing, was high (19.9 Mg ha-1), showing its potential for shortterm firewood production. Total nutrient uptake for production of woody biomass (200 days of growth) was no more demanding than growing the plant to the green-manuring stage of 50–60 days' growth.

The reproductive biology of three perennial Sesbania species (Leguminosae)

The reproductive biology of Sesbania sesban, S. goetzei and S. keniensis (Leguminosae; Papilionoideae) was studied. Fifty percent flowering was observed at 102 to 153 days after germination for S. sesban accessions; 96 to 146 days for S. goetzei and 131 to 176 days for S. keniensis accessions. Flowers opened in the afternoon and remained fresh for 2–3 days. Bee species including Xylocopa sp., Apis mellifera, Megachile bituberculata and Chalicodoma sp. visited the flowers. Hand pollination experiments showed that all three species were self and cross compatible. The percentage of fully developed seeds was greater in pods formed after cross pollination compared to self pollination. No evidence was found for stigmatic or stylar self incompatibility. Outcrossing is probably the common method of reproduction under natural conditions, although in isolated trees substantial seed set by selfing might occur. Pod production under natural conditions was 34% for S. sesban; 49% for S. goetzei and 39% for S. keniensis. Considerable variation was found in pod production under open pollination between accessions of the same species. Selective abortion was observed within pods, with more mature seeds formed at the distal end of the pod.