Global description
Sesbania bispinosa is a sub-woody upright plant, branched, reaching up to 2 to 3.5 m high. Young stems bear small sparsed spines. The leaves are alternate, paripinnately compound with numerous leaflets. The flowers are assembled in small axillary clusters. The fruit is a linear, curved pod, 15 to 28 cm long, containing numerous oblong seeds, ending in a sharp beak of 1 to 1.5 cm.
Cotyledons
Cotyledons are oblong, roughly kidney-shaped, briefly stalked.
First leaves
The first leaf is simple, shortly petiolate, with more or less elliptical leaf blade, margin entire. The following leaves are paripinnately compound and alternate, with 5 to more than 10 pairs of leaflets.
General habit
Large upright sub-woody grass, annual or perennial short lived, with branched stem, 1 to 3.5 m high.
Underground system
Taproot system.
Stem
The stem is cylindrical and solid, more or less lignified at the base, branched, carrying small sparsely dispersed spines. It is more or less pubescent on younger parts.
Leaf
The leaves are paripinnately compound, alternate, generally 10 to 30 cm long; petiole about 2 cm long and stipules very narrowly linear-ovate, 6 to 10 mm long, deciduous; the leaflets are generally 20 to 50 pairs, linear-oblong, 8 to 20 by 1.5 to 4 mm. Young leaves are pubescent, but quickly becoming glabrescent.
Inflorescence
The inflorescences are racemes, 2 to 18 cm long, with 3 to 12 flowers in the axils of leaves; pedicels 5 to 10 mm long.
Flower
The calyx is cup shaped, 3 to 4 mm long, glabrous except on the margin. The papilionaceous type corolla, consists of a pale yellow or cream standard, mottled with brown or purple, lamina 9-15 mm by 8-14 mm; lateral petals (wings) of yellow color and more or less as long as the keel (9 to 13 mm).
Fruit
The fruit is a linear, curved pod, 15 to 28 cm long and about 3 mm wide, containing 28-45 seeds; rostrum 1 to 1.5 cm long; the pod is marked by bottlenecks at the bulkhead separating the loculus.
Seed
Seeds are oblong, elliptical cross-section, 3-3.5 mm x 1.5 mm x 1.2 mm, brown to olive green or greenish black in colour.