Indigastrum

Taxonomy

Indigastrum H.F. Jaubert & É. Spach Ill. Pl. Orient. 5: 101. t. 492. Feb 1857.

Subfamily: Faboideae.
Phylogenetic Number: 3.9.05.
Tribe: Indigofereae.
Species Studied - Species in Genus: 3 studied; 9 in genus.

Description

Fruit: A legume; unilocular; 2–5 cm long; ca. 0.2 cm wide; ca. 0.2 cm thick; more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical; linear; not inflated; terete; without beak; tapered at apex; oblique with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; nonstipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; passive. Replum invisible. Epicarp dull; monochrome; brown to tan; with surface texture uniform; pubescent and indurate; with hairs appressed; with 1 type of pubescence; sericeous; with pubescence hyaline; with pubescence uniformly distributed; with complex hairs; with T-shaped hairs; stiff; with hair bases plain; eglandular; without spines; smooth; not veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; glossy; translucent; monochrome; hyaline; smooth; without adhering pieces of testa; subseptate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 11–14; length parallel with fruit length; touching; in 1 series. Funiculus ca. 0.2 mm long; of 1 length only; flattened; triangular. Aril absent.

Seed: 1.5–1.6 mm long; 1.1–1.6 mm wide; 0.8–0.9 mm thick; not overgrown; angular; symmetrical; quadrangular to rectangular, or irregular; compressed; with surface smooth; without visible radicle and cotyledon lobes; with shallow 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; dull; not modified by a bloom; colored; streaked and mottled, or mottled (with very tiny spots); with frequent mottles; with frequent streaks; olive; with brown overlay, or purple overlay; glabrous; smooth; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform (0.1–0.2 mm); flush; not within corona, halo, or rim. Lens discernible; 0.2–0.3 mm long; with margins curved; elliptic; not in groove of raphe; confluent with hilum; flush; dissimilar color from testa; darker than testa; brown; not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; restricted to region of embryo; adnate to testa. 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; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; light rusty brown; inner face flat; glabrous on inner face. Embryonic axis oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip straight; oblique to cotyledons; not centered between cotyledons (radicle outside 1 cotyledon and inside other, therefore junctions for each cotyledon different); 1/2 to nearly length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Southern and eastern Africa.

Old World; southern and eastern Africa.

Generic Notes

Schrire (1992, 1995) carried out cladistic analyses using morphical characters and chromosome numbers. Two of his conclusions were that Indigastrum and Microcharis (3.9.04) should separated from Indigofera (3.9.07) as good genera. Polhill (1994a, 1994b) agreed with his conclusions.

Tribal Notes

Tribe Indigofereae

Schrire (1995) carried out extensive cladistic anaylses with Indigofereae genera and infrageneric taxa of Indigofera (9.07).