THAI FOREST BULLETIN (BOTANY) 36
those on the stem, sparse above, abundant beneath especially on veins; stipels 4–5 mm. Inflorescences axillary, ca 17 cm long, main axis unbranched with ultimate branchlets knob- like, rather few, only 3–5, all crowded in upper third of axis; pedicels only ca 8 mm long with short (ca 0.4 mm) dense adpressed, silvery, silky pubescence, main axis similarly hairy towards apex but pubescence more like the stem towards base; bracts and bracteoles small relative to flower size, 10 by 4 mm, narrowly ovate, acute. Calyx with dense silky hairs like the pedicels and fine brownish bristles, tube ca 8 by 12 mm, lobes long, lowest ca 8 mm, laterals ca 6 mm long, all 2–3 mm wide, triangular, acute; upper lip well marked, exceeding lateral lobes. Corolla long and narrow, 2-coloured, standard and wings dark bluish-purple, keel white; standard 3 cm long, wings 6–6.3 by 1.5 cm equalling keel. Fruit unknown.
Thailand.— NORTHERN: Lamphun [Me Kaw, init 1541 (holotype K!)]. Distribution.— Endemic to Northern Thailand. Ecology.— Forest, 250 m alt.
Notes.— This distinctive species is only known from one collection and is presumed to be very rare and local. The full range of variation in leaves and flowers may not be completely apparent from the only collection known of this species. Its fruit and seed are unknown but assumed to conform to M. subgenus Stizolobium, since vegetatively M. gracilipes is almost identical to M. pruriens and M. bracteata in its rhombic-ovate leaves with lateral veins running into the margin. It differs markedly in that its petals are much larger (wings twice as long) with different relative proportions and clearly two coloured, the keel being white rather than light purple and not longer than wing.
Mucuna pruriens (L.) DC., Prodr, 2: 405. 1825; Gagnep. in H.Lecomte, Fl. Indo-Chine 2:
1916; Craib, Fl .Siam 1: 444. 1928; Van Thuan, Fl. Camb. Laos Vietnam 17: 31. 1979;
Pinratana, Flowers in Thailand 9: 47 & Fig. 1981. Type: Indonesia, Amboina [Rumphius, Herb.Amb. 3 t. 142. 1750].
Slender climber often up to several metres long. Leaves and leaflets very variable in size; terminal leaflet 3–16 cm long, elliptic to rhombic-ovate, lateral veins 5–8, (straight or) gently curved throughout length and running clearly into margin; lateral leaflets with base of abaxial half usually truncate; stipels conspicuous 4–5 mm long, filiform or robust. Inflorescence usually long, up to 40 cm, main axis slender, unbranched with (few–)10–20 knob-like ultimate branches in upper S– of axis; lower part of axis without either bracts or scars. Calyx with dense adpressed, silvery or brownish pubescence and often also irritant red bristles, tube 5–10 mm long, upper lip usually exceeding lateral lobes. Corolla dark purple (rarely white); wings broadly rounded, usually shorter than keel. Fruit narrowly linear-oblong, 3–6-seeded, often curved into “S-shape”, 5–9 by 0.8–1(–2) cm, slightly laterally flattened ca 0.5 cm thick; surface with dense irritant bristles or silky hairs, sometimes ornamented with partial longitudinal ridges. Seed ellipsoid, small, 1–1.7 (–2) by 0.7–1.3 cm, hilum occupying ca 1/8 of circumference.
M. pruriens is similar to M. bracteata in its rhombic-ovate leaves with lateral veins running into margin, inflorescence axis with flowers all in upper S–[ of axis, small flowers and small linear oblong fleshy fruit usually with irritant hairs. It differs in its thin-textured leaves with slender, less conspicuous lateral veins, slender inflorescence axis without