Cojoba

Taxonomy

Cojoba N.L. Britton & J.N. Rose N. Amer. Fl. 23: 29. 11 Feb 1928.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.5.22.
Tribe: Ingeae.
Species Studied - Species in Genus: 7 studied; 12 in genus.

Description

Fruit: A legume; unilocular; 2–22 cm long; 0.6–3.8 cm wide; 0.6–3.8 cm thick; 2–9 times longer than wide, or more than 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; 0.5-coiled to 1-coiled, or straight to curved; not plicate; twisted, or not twisted; symmetrical, or asymmetrical; oblong, or falcate to C-shaped (appearing moniliform); with both sutures parallelly curved; not inflated; terete; without beak; rounded at apex to short tapered at apex; aligned with longitudinal axis of fruit; short tapered at base, or rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous, or fleshy (when young), or leathery (when mature); seed chambers externally visible, or invisible; margin constricted, or not constricted; margin constricted along both margins, or slightly constricted along both margins; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 10 mm long, or 25–45 mm long; with all layers dehiscing, or with epicarp and mesocarp dehiscing and endocarp not dehiscing (tardily, after falling from tree, Obolinga); splitting along suture(s). Dehiscence of valves along 1 suture (ventrally), or both sutures; medial and up and down, or apical and down; active, or passive (valves shrinking back and spilling the seeds in Obolinga); with valves twisting (remaining attached to sutures). Replum invisible. Epicarp dull; monochrome; grayish to reddish brown; with surface texture uniform; pubescent and indurate to glabrous, or pubescent but soon deciduous to glabrate; with hairs erect; velutinous; with simple hairs; eglandular; without spines; not smooth, or smooth (sometimes when exfoliating revealing a smooth surface); with elevated features; not veined, or veined (sometimes when exfoliating revealing reticulate veination); reticulately veined; not tuberculate; prominently or not wrinkled; not exfoliating to exfoliating (if exfoliating revealing blackish to reddish smooth to reticulate surface); without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; glossy, or dull; opaque; monochrome; dark brown to tan, or red; smooth to fibrous; without adhering pieces of testa; septate, or nonseptate; coriaceous; not exfoliating; entire. Seed(s) 8–12, or 20–28; length parallel with fruit length, or transverse to fruit length; neither overlapping nor touching, or touching (in sects. Ophidinga and Obolinga); in 1 series, or 2 or more series. Funiculus 1.5 mm long, or 3–4 mm long; of 2 different lengths, or 1 length only; thick, or partially filiform and partially thick (obliquely ovate or lanceolate); straight, or curved. Aril absent.

Seed: 7.7–28 mm long; 5.5–12 mm wide, or 20–28 mm wide; 4–12 mm thick; not overgrown; not angular; symmetrical; oblong to circular; terete (or nearly so), or quadrangular (intermediate seeds discoid in Obolinga, often thinner at one edge or sometimes wedgelike), or mounded on 1 side and straight on other side (seed (2) at each end of Obolinga fruit hemispherical or plumply half-ellipsoid); with surface smooth; without visible 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; not modified by a bloom; colored; monochrome; bluish black to black, or brown (dark); glabrous; not smooth, or smooth; with elevated features and recessed features; rugose, or wrinkled (coarsely); pitted with small separate pits; coriaceous, or chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible, or not visible; from lens to base of seed and terminating; not bifurcating. Hilum present; visible, or fully concealed; concealed by funicular remnant; without faboid split; larger than punctiform, or punctiform; with angular outline, or curved outline; circular; irregular; subapical to radicle tip, or apical at apex of radicle tip; recessed (or nearly so), or flush; not within corona, halo, or rim. Lens not discernible, or discernible; ca. 30 mm long; with margins straight; linear; not in groove of raphe; mounded; same color as testa; brown; not within corona, halo, or rim. Endosperm absent. Cotyledons smooth; both outer faces flat; both the same thickness (in Obolinga each with one broad flattened outer and one thinner inner margin); both more or less of equal length; not folded; margin entire 180 degrees from base of radicle, or not entire 180 degrees from base of radicle; similar at apex; completely concealing radicle, or partially concealing radicle; with lobes; with lobes overlapping; with basal groin formed by lobes; with the interface division terminating at base of radicle; without margins recessed; ivory white, or green (prior to germination); inner face flat, or concave; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; straight with embryonic axis; centered between cotyledons. Plumule well developed; glabrous.

Distribution

Generic Notes

The fruits of Cojoba spp. change in shape, size, and surface topography before and after dehiscence. When seeds are present, the fruits are moniliform and turgid (D), and when seeds are no longer in the fruit, the fruits lose their shape and turgidity (C). Polhill accepted Obolinga (2.5.23) as a good genus. But, Barneby and Grimes (1997) synonmized it under Cojoba, and we are following their placement. The species count and distribution follow Barneby and Grimes.