Amorpha

Taxonomy

Amorpha C. Linnaeus Sp. Pl. 713. 1 Mai 1753.

Subfamily: Faboideae.
Phylogenetic Number: 3.6.04.
Tribe: Amorpheae.
Species Studied - Species in Genus: 15 studied; 15 in genus.

Description

Fruit: A legume; unilocular; 0.4–1.05 cm long; 0.15–0.45 cm wide; 0.14–0.18 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx equal in length to fruit, or shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight to curved (to slightly curved); not plicate; not twisted; asymmetrical; falcate, or oblong; with 1 straight and 1 curved suture, or both sutures parallelly curved, or both sutures unequally curved; widest near middle or D-shaped, or widest near apex; not inflated; compressed; without beak, or with beak; with solid beak the same color and texture as fruit; rounded at apex; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous, or fragile, thinner than chartaceous, like Trifolium; seed chambers externally visible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; substipitate, or nonstipitate; indehiscent. Replum invisible. Epicarp dull; monochrome (sometimes with conspicuously darker colored glandular dots); brown, or tan; with surface texture uniform, or not uniform, with patches of different texture not restricted to the base and apex; glabrous, or glabrate, or pubescent and indurate; with hairs erect; with 1 type of pubescence; puberulent; with pubescence gray; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; glandular, or eglandular; with glandular dots; without spines; not smooth; with elevated features, or recessed features; not veined; not tuberculate; faintly wrinkled; punctate (because of empty glandular dots); not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; glassy beads (reddish to dark-brown); coriaceous. Endocarp present; visible; dull to glossy; opaque; monochrome; reddish brown, or tan; smooth, or vitriol (because of glandular exudates); without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1; length parallel with fruit length. Funiculus filiform, or thick; straight. Aril present, or absent; dry; when dry rim-aril; entire; light tan.

Seed: 2.5–5 mm long; 1.6–3 mm wide; 1.1–1.3 mm thick; not overgrown; not angular; asymmetrical; D-shaped, or elliptic, or oblong (all with radicular beak); compressed; with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy (because of glandular exudate), or dull; not modified by a bloom; colored; monochrome; brown (reddish to orange to olive), or tan, or black; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Raphe visible; from hilum to lens, or hilum to near base of seed and terminating; not bifurcating; darker than testa; tan, or brown (dark to light); flush. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; between cotyledon and radicle lobe; recessed; within rim; rim color of testa (essentially). Lens discernible, or not discernible; with margins curved; circular, or elliptic; not in groove of raphe; adjacent to hilum; 1.5 mm from hilum; barely mounded; dissimilar color from testa; darker than testa; dark brown; not within corona, halo, or rim. Endosperm present; thick; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to testa, or embryo. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle (barely); split over radicle; with lobes; with lobes not touching; with the interface division terminating at base of radicle; without margins recessed; green, or tan; inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip curved; deflexed and parallel to cotyledon width; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary to moderately developed; glabrous.

Distribution

United States and Canada.

New World; Canada to United States to Mexico.

Generic Notes

Palmer (1931) monographed Amorpha and illustrated its fruits, and Wilbur (1975) described the fruits and seeds in his revision of the genus. We followed the latter revision.

Tribal Notes

Tribe Amorpheae
Traditionally this tribe has been called Amorpheae. Reveal (1997) reported that the name Daleeae was published before the name Amorpheae. Following the International Code of Botanical Nomenclature (Greuter et al., 1994), the oldest name for a taxon must be used, so Reveal suggested that this tribe should called Daleeae. In 1999 Reveal (1999) reversed himself, so that the tribe remains the Amorpheae.