Melolobium

Taxonomy

Melolobium C.F. Ecklon & J.M. Zeyher Enum. 188. Jan-Feb 1836.

Subfamily: Faboideae.
Phylogenetic Number: 3.30.01.
Tribe: Genisteae.
Species Studied - Species in Genus: 8 studied; ca. 20 in genus.

Description

Fruit: A legume; unilocular; 0.8–2 cm long; 0.3–0.5 cm wide; 0.08–0.2 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight, or curved; not plicate; not twisted; asymmetrical, or symmetrical; linear, or ovate to oblong (narrowly); with both sutures nearly straight; not inflated; compressed; without beak; short tapered at apex; aligned with longitudinal axis of fruit; short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; seed chambers with the raised seed chambers torulose; margin constricted; margin slightly constricted along both margins; margin without sulcus; margin plain; wing(s) absent; substipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves slightly twisting. Replum invisible. Epicarp dull; monochrome, or multicolored; mottled; brown, or tan; with reddish brown overlay; mottling color combination constant; with mottling over seed chambers; with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence; tomentose; with pubescence golden, or gray; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; warty; 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; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; brown (reddish); smooth; without adhering pieces of testa; subseptate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1–8; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; flattened; straight. Aril present, or absent (so tiny that it can be missed); dry; when dry tiny tongue-aril; entire; white.

Seed: 2–2.5 mm long; 2–2.5 mm wide; 1.5 mm thick; not overgrown; not angular; asymmetrical; ovate to circular (sub); compressed; without visible radicle and cotyledon lobes; 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; monochrome, or mottled; with frequent mottles; reddish to dark reddish brown; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed; concealed by aril; 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, or lighter than testa, or darker than testa. Lens discernible; with margins straight, or curved; irregular; irregular, or key-hole shaped; not in groove of raphe; adjacent to hilum; 0.1–0.2 mm from hilum; mounded; dissimilar color from testa; darker than testa; black (at least center); not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to 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; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; yellow, or green; 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; linear; deflexed and parallel to cotyledon length; centered between cotyledons; 1/2 to nearly length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Southern Africa.

Old World; Africa (southern).

Generic Notes

Polhill (1981q) and Van Wyk (1991) had Melolobium in Crotalarieae, but later transferred it to the beginning of the Genisteae (32; Polhill, 1994a, 1994b; Van Wyk and Schutte 1995a).

Tribal Notes

Tribe Genisteae

Traditionally this tribe has been called Genisteae. Reveal (1997) reported that the name Cytiseae was published before the name Genisteae. 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 be called Cytiseae. In 1999 Reveal (1999) reversed himself, so that this tribe remains the Genisteae. Bisby (1981) summarized tribe Genisteae, following the excellent study by Polhill (1976). Bisby correctly noted that "many species have been moved from one genus to another several times and the Cytisus-Genista complex has gained a reputation as a critical group." He continued with an indepth analysis of the tribe. Polhill (1994a, 1994b) and Van Wyk and Schutte (1995a), using chemical and morphological characters, transferred five genera from Crotalarieae (27) to Genisteae: Anarthrophyllum (30.06), Argyrolobium (30.03), Dichilus (30.02), Melolobium, and Sellocharis (30.07). Cristofolini (1997) carried out a cladistic study of the tribe's biogeography, and discussed its early evolutionary history. López et al. (2000) studied the species of this tribe occurring in southwestern Spain and presented detailed descriptions for and a key to them.