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MUCUNA ADANS. (LEGUMINOSAE) IN THAILAND (C.M. WILMOT-DEAR)

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wing petals is diagnostic and shape of the wings (somewhat narrowed towards the apex versus widened and rounded towards the apex) is sometimes diagnostic. Fruit texture (woody, leathery or fleshy), size and shape separates various groups of taxa. Ornamentation of fruit is important: dorsal and ventral sutures may be ornamented with a pair of wings and the lateral faces may be ornamented with transverse lamellae of uniform or irregular width; these lamellae are either simple raised flaps or are bifurcated distally to give “T-shape” in cross-section, and may be continuous across the whole pod width, all interrupted along its midline or irregularly interrupted.

MUCUNA

Adans., Fam. Pl. 2:325. 1763; Prain, J.Asiat. Soc. Bengal 66: 404. 1897, nom. cons.

Herbaceous or woody climbers. Leaves trifoliolate, lateral leaflets ± asymmetrical, stipules and often stipels caducous. Inflorescences axillary on leafy shoots or on old branches, mostly a pseudo-raceme through reduction of ultimate branchlets (secondary axes) or sometimes subumbellate; bracts and bracteoles caducous. Flowers conspicuous, purple, red, greenish, yellow or white. Calyx 4–5-lobed, 2-lipped, upper pair of lobes connate to form entire or bifid lip. Standard petal rounded with median claw and pair of inflexed lateral auricles at base, much shorter than other petals; wing and keel petals narrowed proximally into basal claw with small dorsal auricle; keel petals partly connate along lower margin, horny and usually pale and hooked at apex. Vexillary stamen free; 5 longer sub- basifixed anthers alternating with 5 shorter versatile or dorsifixed often barbate anthers on apically swollen filaments. Ovary with few to many ovules; style long, filiform, sometimes pubescent but not bearded, bent; stigma small, terminal. Fruit ovoid, ellipsoid, oblong, linear or torulose, often markedly dorsiventrally flattened; valves thick and often ribbed or ornamented with raised lamellae and frequently bearing irritant bristles, septate between seeds, mostly dehiscent; margins often winged. Seeds globose or oblong with short or linear hilum and conspicuous rim-aril or discoid to oblong with elongated hilum occupying over ½ circumference and no aril.

Approximately 100 species in the tropics and subtropics. 13 species native to Thailand.

KEY TO THE SPECIES IN THAILAND, INDOCHINA, PENINSULAR MALAYSIA AND SINGAPORE

A. Flowering material

  • 1.

    Lateral veins of leaflets gently curved throughout most of their length but near margin more sharply curved and (in Thailand) never clearly running into margin but always becoming indistinct or running parallel to margin; terminal leaflet elliptic or ovate; wing petals narrowing near apex (A. Subgenus Mucuna)

    • 2.

      Stems and leaves with conspicuous red-brown indumentum.

    • 3.

      Leaflets without persistent stipels, abaxial half of lateral leaflets truncate at base; distal part of margin of standard and wings with border of short but distinct pubescence; ultimate branchlets

always reduced and knob-like

1. M. macrocarpa

3. Leaflets with persistent stipels, lateral leaflets rounded at base; petals glabrous except in basal (claw) region; ultimate branchlets of inflorescence often slightly lengthened (2–4 mm).

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