Strongylodon

Taxonomy

Strongylodon J.R.T. Vogel Linnaea 10: 585. 1836.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.02.
Tribe: Phaseoleae.
Subtribe: Erythrininae.
Species Studied - Species in Genus: 2 studied; 12 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 4–36 cm long; 2–6 cm wide; 1.2–4 cm thick; 2–9 times longer than wide, or length less than twice as long as width; 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; symmetrical, or asymmetrical; ovate (or nearly so), or oblong, or linear (Huang, 1991), or moniliform (Huang, 1991), or irregular; with both sutures parallelly curved, or both sutures unequally curved; inflated, or not inflated; terete; without beak, or with beak; straight, or coiled (Huang, 1991), or hooked; with solid beak the same color and texture as fruit; short tapered at apex, or rounded at apex (Huang, 1991); aligned with longitudinal axis of fruit, or right-angled with longitudinal axis of fruit (Huang 1991); tapered at base, or short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous to leathery, or fragile, thinner than chartaceous, like Trifolium; 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 (slightly); wing(s) absent; stipitate, or nonstipitate (Huang, 1991); with the stipe 2–15 mm long; with all layers dehiscing, or indehiscent; splitting along suture(s). Dehiscence of valves along both sutures; apical and down. Replum invisible. Epicarp dull; monochrome; tan to brown; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; rugose; exfoliating in part; with cracks, or without cracks; cracking irregular; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present, or absent; thin; 1-layered; without balsamic vesicles; without reniform canals; fibrous throughout; chartaceous. Endocarp present; visible; dull; opaque; monochrome; tan, or yellow (golden); smooth; without adhering pieces of testa; nonseptate, or subseptate (S. loheri S.-F. Huang); chartaceous; exfoliating; remaining fused to mesocarp and epicarp; separating from epicarp; without wings; entire. Seed(s) 1–12; length parallel with fruit length, or transverse to fruit length (Huang, 1991); neither overlapping nor touching; in 1 series. Funiculus 0.5–55 mm long; of assumed 1 length only; partially filiform and partially thick; straight, or triangular. Aril absent, or present (Strongylodon craveniae R. Baron & Baker and S. madagascariensis Baker (Du Puy et al., 2002)); fleshy; when fleshy marginal hilar; crenate; covering less than 1/2 of seed; white to cream.

Seed: 9–40 mm long; 9–34 mm wide; 10–33 mm thick; not overgrown; angular, or not angular; asymmetrical; nearly circular, or D-shaped (rounded), or irregular; terete (to wider than thick); with surface ridged, or 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, or partially adhering to endocarp; free from endocarp; dull, or glossy; not modified by a bloom; colored; monochrome; dark brown to black; glabrous; smooth, or not smooth; with recessed features; cracked; coriaceous, or chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent, or present; transverse. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by funicular remnant; without faboid split; larger than punctiform; (23–)45–57 mm long; with curved outline, or straight outline; circular; linear (around 3/4 of seed); marginal according to radicle tip; raised, or recessed; within rim, or not within corona, halo, or rim; rim color of testa. Lens discernible, or not discernible; 0.5–1.5 mm long; with margins straight; linear; not in groove of raphe; adjacent to hilum; recessed; same color as testa; brown; not within corona, halo, or rim. Endosperm present, or absent; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to embryo. Cotyledons smooth, or not smooth; sulcate; 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; split over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; tan; inner face flat to concave (slightly); glabrous on inner face. Embryonic axis oblique; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle slightly differentiated from cotyledon; linear, or triangular; lobe tip straight; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule moderately developed to well developed; glabrous.

Distribution

Madagascar to Polynesia.

Old World; Madagascar, Indian Ocean, India, Indonesia and the Philippines, New Guinea, Australia, Pacific, Fiji, and Hawaii.

Generic Notes

Strongylodon has 20 species according to Lackey (1981). Huang (1991) monographed the genus and recognized 12 species, and we used the latter count. The embryo is very unusual. The plumule is highly developed. The radicle points towards the center of the cotyledons, and the epicotyl points to the outside of the cotyledons. Consequently the plumule is exserted from the cotyledons, and the radicle is near the their center.

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.