Piptadenia

Taxonomy

Piptadenia G. Bentham J. Bot. (Hooker) 2: 135. Apr 1840.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.3.22.
Tribe: Mimoseae.
Group: Piptadenia.
Species Studied - Species in Genus: 13 studied; ca. 15 in genus.

Description

Fruit: A legume; unilocular; 6–18 cm long; 0.7–4 cm wide; 0.3–0.8 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 to curved; not plicate; usually undulate and not twisted; symmetrical; oblong to linear, or moniliform; not inflated; flattened to compressed; without beak; rounded at apex; aligned with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous to coriaceous; seed chambers externally visible, or invisible; margin not constricted to constricted; margin constricted along both margins, or constricted only on 1 margin; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 10–15 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures, or 1 suture (along ventral margin (P. obliqua), remaining attached to sutures); apical and down; passive. Replum invisible. Epicarp dull; monochrome; brown (to grayish brown); with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features, or recessed features; not veined; not tuberculate; shagreen and scaly (on moniliform fruits); sometimes punctate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; glossy to dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; nonseptate to septate; not exfoliating; entire. Seed(s) 3–12; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus up to 7 mm long; of 1 length only; thick; plicate. Aril absent.

Seed: 6–20 mm long; 4–15 mm wide; 1–3 mm thick; not overgrown; not angular; symmetrical; elliptic to circular (sub); compressed; 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; dull to glossy; not modified by a bloom; colored; monochrome; blackish brown to tan, or black; glabrous; smooth, or not smooth; with elevated features; when raised rugose; osseous to chartaceous. Pleurogram present, or absent; 75 %. Pseudopleurogram absent. Fracture lines present, or absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; without faboid split; punctiform; apical at apex of radicle tip; flush; not within corona, halo, or rim. Lens discernible; 0.2–0.5 mm long; with margins straight, or curved; linear; elliptic; not in groove of raphe; flush (to nearly so); same color as testa, or similar color as testa, or dissimilar color from testa; lighter than testa, or darker than testa; tan; not within corona, halo, or rim. Endosperm present, or absent; when present thick; not pluglike and not resembling tip of radicle; adnate to testa. Cotyledons not smooth; rugose; both outer faces flat; 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, or not concealing radicle; notched at radicle; with lobes; with lobes touching (auriculate); without basal groin formed by lobes; with the interface division terminating at base of radicle; without margins recessed; inner face flat; 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 to rudimentary; glabrous.

Distribution

Tropical South America and southern Central America.

New World; southern Central America, West Indies, Mexico, and South America (tropical); Argentina, Peru, Brazil, Ecuador, and the Guianas.

Generic Notes

Piptadenia has two distinct fruit types, moniliform and oblong to linear, and two distinct seed types. Seeds are either pleurogrammatic, smooth, and endospermic or nonpleurogrammatic, rugose, and nonendospermic. Bravato (1974) opined that there may be more than one section in this genus. The illustrated and studied species may represent more than one genus. A monograph is needed.