Sesbania herbacea (Miller) McVaugh, coffee bean, colorado river–hemp, sesbane, bequilla. Robust annual, taprooted in permanently wet substrate, 1–stemmed at base, with spreading–ascending lateral branches often with terminal inflorescence, erect, 50—400 cm tall; shoots with only cauline leaves, leaflets having sleep movements, glabrous and glaucous, not gland–dotted, having a somewhat unlikable odor when wounded.
Stems cylindric, to 40 mm diameter at base, axes ± straight, internodes 10—40 mm long, with persistent leaf bases ca. 2 mm long, grayish green nearly to plant base or with some periderm formation, old stems woody and with tough fibers in outer stem (phloem fibers).
Leaves helically alternate, even–1–pinnately compound with to 107 lateral leaflets mostly in pairs (extremely long leaves with alternate leaflets below pairs and alternate leaflets above pairs), petiolate with pulvinus, with stipules; stipules 2, attached to projecting leaf base below pulvinus, ascending to spreading, long–acuminate to linear–lanceolate, 7—12 × 1 mm, gray–green and glaucous, early–deciduous; petiole having pulvinus at base, ca. 5 mm long, yellow–green; commonly with leaflets arising at base of rachis directly above pulvinus on upper side of rachis; rachis to 460 mm long, strongly 2–ridged and channeled, pairs + 7 mm apart, with short extension beyond the uppermost pair of leaflets; stipels 2 attached to base of petiolule, clawlike, 0.7—0.9 mm long (—2 mm long on the lowest pair), yellow–green; petiolule with pulvinus cylindric, ± 1 mm long; blade oblong to oblanceolate, 150—465 mm long; blades of leaflets ⊥ rachis, symmetric, oblong to oblanceolate, 18—35(—50) × 2.2—9.3 mm, ± rounded at base, entire, ± rounded with point to 0.5 mm long at tip, pinnately veined with midrib raised on lower surface.
Inflorescence raceme, axillary, 2—6–flowered, bracteate, glabrous; peduncle at anthesis to 10 mm long increasing 2—3× in fruit; bractlet subtending pedicel, awl–shaped flared at bersistent base, 5—6 × 1 mm, partially sheathing; pedicels to 3.5 mm long increasing 2× in fruit, with 2 opposite bracteoles at top subtending flower, bracteoles awl–shaped ca. 3 × 0.4 mm, abscising before anthesis leaving persistent bases in fruit.
Flower bisexual, bilateral, modified pealike (papilionaceous), ca. 8 mm across and tall; calyx 5–lobed, somewhat glaucous; tube asymmetrically bell–shaped, ca. 5 × 6 mm; lobes ± deltate (in bud narrowly triangular), ca. 2 mm, light green, short–tomentose on inner surface of lobes and on margins; petals 5, clawed; banner claw about 3 mm long, greenish; limb somewhat heart–shaped notched at top and tapered at base, ca. 12 × 16 mm, faded light yellow with darker spreading veins; wings 2, claws linear, ± 4 mm long, yellowish, limbs obovate, ca. 12 × 5 mm, ca. 2.2 mm wide at base above short lobe, light yellow; keel of 2 petals fused ca. 4 mm on outer edge approaching tip, claws ca. 6 mm long, limbs broadly crescent–shaped, 7 × 4 mm, faded light yellow tinged purplish above midpoint, sharply bent, with dentate tooth on upper side, tops free; nectary surrounding stalk and base of ovary, vase–shaped, 1.5 × 1.5 mm, green, fleshy, 5–lobed on inner side, producing some nectar in bud; stamens 10, diadelphous (9 fused and 1 free), included (not visible); filaments strongly bent a. 135° appearing 12 mm long, sheet ± 9 mm long and free portions equal alternating 5 and 6 mm long, white; anthers dorsifixed, dithecal, 1—1.3 mm long, pale yellow, longitudinally dehiscent; pollen whitish, sticky; pistil 1, 18—19 mm long, short–stalked (stipe) < 1 mm long; ovary superior, ± cylindric with sides somewhat flattened, green, glabrous, 1–chambered with 30+ ovules attached to upper side; style curving from end of ovary and bent 90 °, pale green; stigma terminal.
Fruit pod (legume), dry, dehiscent along both sides, typically 30—35–seeded, ± drooping, slender and ± cylindric straight or slightly curved upward, 150—210+ × 3.3—3.8 × 2—2.3 mm, with seeds regularly spaced and slightly bulging, brown with darker streaks, with beak < 10 mm long, glabrous; on stalk < 4 mm long.
Seed± broadly ellipsoid to oblong compressed side–to–side with truncate to rounded ends, 2.6—4.2 × 1.7—2.4 × 1.2—1.5 mm, dull brown mottled with black spots, smooth, with indented, circular hilum slightly off center.
A. C. Gibson