Oxyrhynchus

Taxonomy

Oxyrhynchus T.S. Brandegee Univ. Calif. Publ. Bot. 4: 270. 26 Jun 1912.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.68.
Tribe: Phaseoleae.
Subtribe: Phaseolinae.
Species Studied - Species in Genus: 3 studied; 4 in genus.

Description

Fruit: A legume; unilocular; 4–10 cm long; 1.8–3.6 cm wide; 1.5–2.5 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; not plicate; not twisted; asymmetrical, or symmetrical; fusiform; with 1 straight and 1 curved suture; widest near middle or D-shaped; not inflated; compressed, or terete; with beak; straight, or declined; with solid beak the same color and texture as fruit; short tapered at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; tapered at base, or rounded at base; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous, or coriaceous; seed chambers externally visible, or invisible; seed chambers with the raised seed chambers not torulose; margin not constricted; margin without sulcus; margin plain, or embellished; margin with thickened sutural areas; wing(s) absent; nonstipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves twisting. Replum invisible. Epicarp dull; multicolored; mottled; brown; with brown overlay; mottling color combination variable; with surface texture uniform; pubescent and indurate, or pubescent but soon deciduous; with hairs erect; with 1 type of pubescence; puberulent, or sericeous; with pubescence golden; with pubescence uniformly distributed; with simple hairs; pliable; 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 present; thick; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; chartaceous. Endocarp present; visible; dull; opaque; monochrome; white to tan; cobwebby, scurfy, smooth, and floury-filamentous; without adhering pieces of testa; subseptate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; exfoliating in part; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1–4; neither overlapping nor touching; in 1 series. Funiculus at least 4 mm long; of 1 length only; thick; anvil-shaped. Aril present, or absent; dry; when dry 2-lipped rim-aril; entire; without tongue (or flap) on lips of 2-lipped rim-aril; cream.

Seed: 13–20 mm long; 13–19 mm wide; 11–18 mm thick; not overgrown; not angular; symmetrical; circular, or elliptic (broadly); terete; 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 to dull; not modified by a bloom; colored; monochrome; black to brown; glabrous; smooth, or not smooth; with elevated features; wrinkled; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present, or absent; reticulate. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible, or partially concealed, or fully concealed; concealed by funicular remnant, or aril; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; 13–25 mm long; with straight outline; linear; marginal according to radicle tip; flush; within rim; rim color of testa. Lens discernible; 2–4 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; flush; same color as testa; brown; within rim; rim color of testa. Endosperm absent. Cotyledons smooth, or not smooth; wrinkled; both outer faces convex; both the same thickness; both more or less of equal length; with both folded, or not folded; sufficiently folded for inner face to touch itself; portions of inner folded face unequal; margin entire 180 degrees from base of radicle, or not entire 180 degrees from base of radicle; notched; similar at apex; partially concealing radicle; notched at radicle; without lobes; with the interface division terminating at base of radicle; with margin(s) recessed; with 1 margin recessed; recessed on same side as radicle; tan; inner face flat; glabrous on inner face. Embryonic axis oblique; 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; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Central America (3 spp.) and New Guinea (1 sp.).

New World, or Old World; West Indies, Mexico, Central America, and South America; Indonesia and the Philippines and New Guinea.

Generic Notes

Seed alignment relative to fruit length could not be determined for this genus because the available fruits all had the seeds detached from the funiculi.

Tribal Notes

Tribe Phaseoleae

Bruneau et al. (1995) carried out cladistic analyses of tribe Phaseoleae using chloroplast DNA restriction site data. Their results indicated that the tribe is not monophyletic and that the tribal delimitations between Phaseoleae and Desmodieae (11) and between Phaseoleae and Millettieae (7) are problematic.