Myrospermum

Taxonomy

Myrospermum N. von Jacquin Enum. Pl. Carib. 4, 20. 15 Mai 1760.

Subfamily: Faboideae.
Phylogenetic Number: 3.2.06.
Tribe: Sophoreae.
Group: Myroxylon.
Species Studied - Species in Genus: 1 studied; 1 in genus, or 2 in genus.

Description

Fruit: A legume; unilocular; 7–12 cm long; 1.7–2.5 cm wide; 0.7–1 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla, or persistent corolla (rarely); with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; asymmetrical; samaroid; with both sutures unequally curved; not inflated; compressed; with beak, or without beak; declined; with papery fragile beak up to 1 cm long; rounded at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; tapered at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; margin not constricted; margin without sulcus; margin plain, or embellished; margin with thickened sutural areas (slightly), or wing(s); wing(s) present; wing(s) 1; wing(s) 45–65 mm wide; wing(s) samaroid; wing(s) basal; substipitate, or stipitate (rarely); with the stipe 1–12 mm long; indehiscent. Epicarp dull; monochrome, or multicolored; mottled; tan; with brown overlay; mottling color combination variable; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; veined; longitudinally veined relative to fruit length (with some reticulate veins); not tuberculate; irregularly papillose; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; 1-layered; with balsamic vesicles; without fibers; without reniform canals; mealy; coriaceous. Endocarp present; visible; dull; opaque; monochrome; tan; rugose; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; with wing(s) extending into epicarp; entire. Seed(s) 1(–3); length parallel with fruit length. Funiculus ca. 1 mm long; thick; convoluted. Aril absent.

Seed: (10–)15–17 mm long; (4–)5.6–7.2 mm wide; 4.5–5.5 mm thick; not overgrown; not angular; asymmetrical; reniform; 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; with frequent mottles; brown; with tan overlay; minutely pubescent (only along hilum); not smooth; with elevated features; rugose; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible; from hilum through lens to base of seed and terminating; not bifurcating; color of testa; flush. Hilum present; fully concealed; concealed by funicular remnant; larger than punctiform; 0.7–1.5 mm long; with curved outline; oval; apical according to radicle tip but marginal according to seed length; raised; not within corona, halo, or rim. Lens discernible; 0.5–1.5 mm long; with margins straight; linear, or triangular; not in groove of raphe; confluent with hilum; flush; similar color as testa; darker than testa; brown; not within corona, halo, or rim. Endosperm absent. Cotyledons not smooth; rugose; 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; notched at radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; tan; inner face flat; glabrous on inner face. Embryonic axis oblique, or parallel; oblique to length of seed, or perpendicular to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip straight; with 180 degree turn; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary to moderately developed; glabrous.

Distribution

Southern Texas to northern South America.

New World; Mexico, West Indies, Central America, and South America; Brazil.

Generic Notes

Delgado Salinas and Johnston (1984) definitively added a second species, M. sousanum A. Delgado Salinas & M.C. Johnston, to genus which extended its range into southern Texas.

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.