Alexa

Taxonomy

Alexa C.H.B.A. Moquin-Tandon In Alph. de Candolle, Prodr. 13(2): 168. 5 Mai 1849.

Subfamily: Faboideae.
Phylogenetic Number: 3.2.12A.
Tribe: Sophoreae.
Group: Angylocalyx.
Species Studied - Species in Genus: 5 studied; 9 in genus.

Description

Fruit: A legume; unilocular; 11–40 cm long; 2.2–7.5 cm wide; 2–5 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical; linear; not inflated; compressed to terete; without beak; short tapered at apex to rounded at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; long tapered at base, or 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, or nonstipitate; with the stipe 5–20 mm long; 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; monochrome, or 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; tomentose to velutinous; with pubescence brown; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; ribbed; not exfoliating, or exfoliating in part; with cracks, or without cracks; cracking oblique to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thick; surface not veined; 2-layered; without balsamic vesicles; without fibers; without reniform canals; with solid layer over solid layer; ligneous. Endocarp present; visible; dull; opaque; monochrome, or mottled; brown, or tan, or yellow; with mottling over seed chambers; with brown overlay; pithy, or scurfy; without adhering pieces of testa; septate; with septa thin (tissue paper-like), flexible, or thicker than paper, firm; with septa eglandular; chartaceous, or pulpy; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) (1–)3–16; length oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus ca. 5 mm long; thick; triangular. Aril present; fleshy; when fleshy irregularly marginal hilar; crenate; covering less than 1/2 of seed; dark brown to black.

Seed: 20–38 mm long; 12–38 mm wide; 10.5–16 mm thick; not overgrown; not angular; symmetrical; circular, or oblong, or ovate; compressed to 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; brown to dark brown; glabrous; not smooth; with elevated features; wrinkled; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent, or present; transverse. Rim absent. Wing(s) absent. Raphe visible, or not visible; from hilum through lens and terminating before base of seed; not bifurcating; color of testa, or darker than testa; brown; flush, or raised. Hilum present; partially concealed, or fully concealed; concealed by funicular remnant, or aril; without faboid split; larger than punctiform; 3–9 mm long; with curved outline, or angular outline; oval; triangular; apical at apex of radicle tip, or subapical to radicle tip; flush; within rim, or not within corona, halo, or rim; rim color lighter than testa. Lens not discernible. Endosperm absent. Cotyledons not smooth; slightly wrinkled; both outer faces convex; both the same thickness, or one thicker than the other; 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; without lobes; with the interface division terminating at base of radicle; with margin(s) recessed; with 1 margin recessed; recessed on same side as hilum (terminal radicle); white to tan; inner face flat, or with central ridge on 1 and central groove on other, or wavy; 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; bulbose; lobe tip straight, or curved; straight with embryonic axis; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Tropical South America.

New World; South America; Brazil and Ecuador.

Generic Notes

Ramfrez (1995) revised the genus. The cotyledons are of distinctly different sizes.

Tribal Notes

Tribe Sophoreae

Polhill (1981b) stated that the Sophoreae s.l. is a tribe of convenience between the Caesalpinioideae and the bulk of the Papilionoideae, sharply defined from neither. He transferred four genera from Sophoreae into the Swartzieae (1), Amburana (3.1.15), Ateleia (3.1.13), Cyathostegia (3.1.14), and Holocalyx (3.1.12), following Herendeen's (1995) cladistic analyses. Herendeen performed cladistic analyses for all Swartzieae genera, sensu Cowan (1981), 19 Sophoreae genera, and three Caesalpinioideae genera. He concluded that Swartzieae is polyphyletic and that it should be disbanded and its genera transferred to Sophoreae. Preliminary rbcL data (Doyle et al. 1997) supported his conclusions.