Phylloxylon

Taxonomy

Phylloxylon H.E. Baillon Adansonia 2: 54. Oct 1861.

Subfamily: Faboideae.
Phylogenetic Number: 3.9.01.
Tribe: Indigofereae.
Species Studied - Species in Genus: 2 studied; 7 in genus.

Description

Fruit: A legume; unilocular; 2.7–6.5 cm long; 1.2–2.1 cm wide; 0.7–1.5 cm thick; length less than twice as long as width, or 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx, or deciduous calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight, or curved (slightly); not plicate; not twisted; asymmetrical, or symmetrical; oblanceolate, or ovate; with both sutures parallelly curved, or both sutures nearly straight; not inflated; compressed, or terete; without beak, or with beak; straight; with solid beak the same color and texture as fruit; long tapered at apex; aligned with longitudinal axis of fruit; short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin constricted, or not constricted; margin slightly constricted along both margins; margin without sulcus; margin plain; wing(s) absent; nonstipitate; indehiscent, or with all layers dehiscing (very tardily (Du Puy, 2002)); splitting along suture(s). Replum invisible. Epicarp dull; monochrome; reddish brown; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; veined; reticulately veined; not tuberculate; slightly wrinkled; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; tan; smooth (but shredding); without adhering pieces of testa; nonseptate; chartaceous; not exfoliating (but in shreds and margins fibrous); remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1(–2) (Du Puy, 2002); length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; thick; straight. Aril absent.

Seed: 12–18 mm long; 10–13 mm wide; 10–13 mm thick; overgrown, 1 seed filling entire fruit cavity (or 2); not angular; asymmetrical; circular, or oblong; terete; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; with 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; not modified by a bloom; colored; monochrome; reddish brown; glabrous; not smooth; with elevated features; wrinkled; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible; from hilum to near base of seed and terminating; not bifurcating; slightly lighter than testa; recessed. Hilum present; fully concealed; concealed by funicular remnant; without faboid split; larger than punctiform; 0.3–2 mm long; with curved outline; circular, or elliptic; subapical to radicle tip; flush; not within corona, halo, or rim. Lens not discernible. Endosperm absent. Cotyledons completely fused forming a single, indivisible mass; not smooth; wrinkled; both outer faces convex; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; tan, or brown; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; truncate; lobe tip straight; deflexed and parallel to cotyledon width; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Madagascar.

Old World; Madagascar.

Generic Notes

Du Puy, Labat, and Schrire (1995) revised the genus Phylloxylon. They changed the name of the commonest, most wide spread species from P. decipiens H.E. Baillon, also type of the genus, to P. xylophylloides, and used P. decipiens for a very narrow Madagascaran endemic. Peltier (1970) studied the seeds and sprouts of P. xylophylloides. He concluded, after examining more than 200 seeds from different localities, that the cotyledons were completely fused without a trace of the line of fusion. Our observations agreed with Peltier's.

Tribal Notes

Tribe Indigofereae

Schrire (1995) carried out extensive cladistic anaylses with Indigofereae genera and infrageneric taxa of Indigofera (9.07).