Gymnocladus

Taxonomy

Gymnocladus J.B.A.P. de M. de Lamarck Encycl. Meth., Bot. 1: 733. 1 Aug 1785.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.1.01.
Tribe: Caesalpinieae.
Group: Gleditsia.
Species Studied - Species in Genus: 3 studied; 5 in genus.

Description

Fruit: A legume; unilocular; 7–25 cm long; 3–5 cm wide; 1–2 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 to curved; not plicate; not twisted; symmetrical, or asymmetrical; ovate, or elliptic to oblong, or falcate; with both sutures parallelly curved; not inflated; compressed; without beak; tapered at apex; aligned with longitudinal axis of fruit; long tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; ligneous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; stipitate to substipitate; with the stipe 0.1–10 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along 1 suture (ventral); passive. Replum invisible. Epicarp dull to glossy, or glaucous; monochrome; dark reddish brown; with surface texture uniform; glabrous; eglandular; without spines; smooth, or not smooth; with elevated features; veined, or not veined; longitudinally veined relative to fruit length; not tuberculate; rugose; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; ligneous. Endocarp present; visible; dull; opaque; monochrome; white; without adhering pieces of testa; septate to nonseptate; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 1–8; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.1–10 mm long; of 1 length only; thick; S-curved to curved. Aril absent.

Seed: 15–20 mm long; 12–20 mm wide; 6–12 mm thick; not overgrown; not angular; symmetrical, or asymmetrical; ovate to circular; 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; dull; not modified by a bloom; colored; mottled; patches of brown and black; glabrous; smooth, or not smooth; with elevated features; rugose; osseous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present; concentric and reticulate. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by funicular remnant; without faboid split; larger than punctiform; 0.1–2 mm long; with curved outline; elliptic to circular; apical at apex of radicle tip; flush to recessed; not within corona, halo, or rim. Lens discernible; 0.1–10 mm long; with margins curved; elliptic; not in groove of raphe; mounded; dissimilar color from testa; black and tan (at center); not within corona, halo, or rim. Endosperm present; thick; not pluglike and not resembling tip of radicle; 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; partially concealing radicle; with lobes; with lobes not touching; with the interface division terminating at base of radicle; without margins recessed; inner face 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; centered between cotyledons. Plumule moderately developed; glabrous.

Distribution

Generic Notes

Lee (1976) monographed the one eastern North American and three (of four) eastern and southeastern Asian species. The funiculus often remains attached to the dehisced seeds. The thick cuticle sloughing off in large pieces during imbibition is unlike most other studied seed in the Fabaceae. The apex of the radicle is broad and blunt because the cotyledons join the embryonic axis at the apex of the radicle as in Moullava (1.26). In other studied caesalpinioid seeds, the cotyledons join the embryonic axis at the mesocotyl. The fruits of Gymnocladus dioicus (L.) K. Koch have been described as 'anachronistic' because they supposedly evolved for dispersal by Pleistocene megafauna that are now extinct (Barlow 2000).