Sesbania
riverhemp
ascending, young growth pubescent or glabrous, hairs simple, long, close-pressed to spreading, pith solid, spongy, or partitioned.
alternate, even-pinnate;
stipules present, caducous, narrowly triangular;
rachis canaliculate;
petiolate, petiole base with stipitate, multicellular glands;
stipels usually present, often persistent, glandular;
leaflets 10–96+, opposite, folding closed at night, blade margins entire, surfaces glabrous or pubescent.
1–18+-flowered, axillary, racemes or panicles, spreading;
bracts and bracteoles present, early deciduous.
papilionaceous;
calyx zygomorphic or actinomorphic, campanulate, undulate-truncate, rim of tube glabrous or hairy, stalked glands sometimes present between lobes, lobes 5 (except sometimes 0 in S. grandiflora), 1/4–1/3 as long as tube;
corolla white, pale yellow to orange or red, with or without purple spots on outer surface of banner, glabrous;
banner usually with a pair of thickened calluses along claw, rarely calluses absent or reduced;
stamens 10, diadelphous;
anthers dorsifixed;
pistil glabrous or style with spreading hairs;
stigma capitate or slightly elongate, at same position as anthers.
legumes, stipitate, bladdery-inflated or long-slender, terete, elliptic, or 4-angled, with or without wings, indehiscent or dehiscent, glabrous, with spongy mesocarp.
1–40(–51), reniform, reniform-orbicular, globose, or columnar;
hilum recessed.
= 6, 7, 12.
Sesbania
Species ca. 70 (7 in the flora).
Darwinia Rafinesque 1817 (not Rudge 1815) and Emerus Kuntze 1891 (not Miller 1754) are illegitimate names that pertain here.
Introduced species of Sesbania are commonly found in agricultural areas within tropical to temperate regions throughout the world.
Sesbania is distinctive among legumes and combines morphologies that are atypical among papilionoids. The most unusual morphology of Sesbania is the even- or odd-pinnate leaf in which the strictly opposite leaflets fold forward during night-time (nyctinasty), similar to the mimosoid clade of Caesalpinioideae (for example, the sensitive Mimosa). Root nodules of Sesbania are variable (produced on roots and laterally on stems) and differ from other legume groups, which generally have uniform nodule morphology (for example, dalbergioids, M. Lavin et al. 2001). Finally, Sesbania fruits are distinctive from other legume groups. They have a well-developed, often spongy, mesocarp having four different variations: tardily dehiscent, linear, and many-seeded (for example, sect. Sesbania); tardily dehiscent, bladdery-inflated, and 2-seeded [sect. Glottidium (Desvaux) Lavin]; indehiscent, 4-winged, and several-seeded [sect. Daubentonia (de Candolle) Bentham & Hooker f.]; and indehiscent, torulose, and several-seeded [Mexican sect. Daubentoniopsis (Rydberg) Lavin]. These divergent fruit morphologies were used traditionally to separate the genus into these four sections, in addition to two others from Africa and the South Pacific.
Species of Sesbania are widely cultivated for multiple agronomic and ecological uses, especially for soil improvement as a green manure (D. O. Evans 1990). Sesbania is used also for shade, as windbreaks, cover crops, ornamentals, fish poisons (isoflavones), fiber sources, construction materials, and food for humans and livestock and for heavy-metal bioremediation (J. B. Gillett 1963; R. Barlow et al. 2000; R. H. Qureshi et al. 2002; Yang B. et al. 2003). However, several species are considered agricultural pests and, in the case of S. punicea, may become noxious weeds in natural wetland and riparian areas.
Unlike the related Loteae and Robinieae, most Sesbania species occupy either riparian or wetland habitats. Many Sesbania are well adapted to fluctuations in soil moisture and are tolerant of both drought and waterlogged conditions, forming floating roots and producing a surrounding layer of spongy aerenchyma to protect stems, roots, and root nodules.
Specimens collected from chrome-ore piles in Maryland and Virginia in the late 1950s by C. F. Reed (1964) were identified as Sesbania exaltata. These collections are actually immature S. bispinosa (Jacquin) W. Wight, which has not been collected in the flora area since. Sesbania bispinosa most closely resembles S. herbacea and S. sericea from which it can easily be distinguished by floral characters. The keel apex of S. bispinosa is reduced and the rectangular blade has a long, downward curved tooth, the banner claw calluses are winglike ridges with rounded apices, and both the peduncle and the leaf rachis are armed with prickles, and the leaflet blades are glabrous abaxially.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Legumes narrow-elongate or flattened; seeds (3–)12–40(–51); keel blades with basal tooth; banners with calluses as ridges or winglike along claw; seeds columnar or reniform-orbicular [sect. Sesbania]. | → 2 |
2. Trees; flowers (5.1–)6.3–7(–7.9) cm; corollas white or red-crimson; banners without purple-maroon spots on outer surface, calluses as shallow ridges along claw; calyx zygomorphic, lobes 0 or 5 and rounded or obsolete; legumes rectangular in cross section, (35.1–)38.7–43.8(–49.7) cm; seeds reniform-orbicular. | S. grandiflora |
2. Herbs; flowers (0.7–)0.8–1.5(–1.9) cm; corollas yellow-orange; banners often with purple-maroon spots on outer surface, calluses as ridges or winglike along claw; calyx actinomorphic, lobes 5, deltate- or subulate-acuminate; legumes ± terete to elliptic in cross section, (1.7–)8.3–19.4(–23.5) cm; seeds columnar. | → 3 |
3. Leaflet blades golden tan-sericeous abaxially; keel apex truncate, curved toward calyx, yellow-orange throughout; seeds without mottling. | S. sericea |
3. Leaflet blades glabrous abaxially; keel apex rounded-acute, curved toward banner, yellow with purple or maroon at apex; seeds often with purple-black mottling. | S. herbacea |
1. Legumes flattened-inflated or 4-angled (sometimes winged); seeds 1–7(–10); keel blades without basal tooth; banners with calluses absent or as small ridges or teeth at claw base; seeds reniform, reniform-orbicular, or globose. | → 4 |
4. Herbs, often woody at base; legumes flattened-inflated, flat to elliptic in cross section; seeds 1 or 2(or 3); peduncles (3.7–)6.4–7.4(–12.2) cm; wings with basal tooth; banner yellow-orange with bright yellow spot at base, wings and keel darker [sect. Glottidium]. | S. vesicaria |
4. Trees, shrubs, or subshrubs, woody; legumes 4-angled (sometimes with wings), square in cross section; seeds (1–)3–7(–10); peduncles (0.6–)0.9–2.4(–4.1) cm; wings without basal tooth; banner pale yellow, yellow, or orange-grenadine-red, sometimes with darker venation, wings and keel ± same color throughout [sect. Daubentonia]. | → 5 |
5. Legumes indehiscent, angles not winged; corollas yellow, banner venation sometimes darker; stems with close-pressed hairs (in age). | S. virgata |
5. Legumes indehiscent or tardily dehiscent, angles winged; corollas yellow or orange-grenadine-red, banner venation not darker; stems glabrous (in age). | → 6 |
6. Corollas orange-grenadine-red; legumes with pronounced, spreading wings, slightly torulose or not, stipes (0.8–)1.1–1.2(–1.6) cm. | S. punicea |
6. Corollas pale yellow; legumes with pronounced torulose wings, stipes (1.1–)1.6(–2) cm. | S. drummondii |
CA
WildflowerSearch
iNaturalist
USDA Plants Database
