THAI FOREST BULLETIN (BOTANY) 36
Calyx with shorter, finer hairs than axis and abundant irritant bristles, tube only ca 7 by 10 mm, lobes short and wide, lowest ca 4.5 by 1.5–4 mm, laterals ca 2 by 2 mm. Corolla dark purple, standard ca 2.5 cm, wings 4–4.5 by 0.6 cm with narrowly rounded apex, keel ± equalling wing. Fruit leathery, 1–(in literature rarely 2)-seeded, asymmetrically oblong to elliptic in outline with very convex margins and often wider than long, 4.5–7.5 by 3.5–5 cm, laterally flattened around the large seed, to 2 cm thick, with hairs like the stem and abundant irritant bristles, surface with 5–6 lamellae of irregular height up to 5 mm in parts, running obliquely transversely from both margins, converging and often interrupted in centre of pod face; both margins with a pair of somewhat undulating wings ± 5 mm wide, some lamellae extending into wings. Seed red-brown, ca 2.8 by 2.4 cm, hilum black.
Thailand.— NORTHERN: Tak [to Pang Ma Kham Pom, Rock 1005 (US); ibid, to Mesawt [Mae Sot], Rock 676 & 1081(US)]; Kamphaeng Phet, [Kerr 2993 (BM, E, K)]; SOUTHWESTERN: Uthai Thani [Ban Rai District, Maxwell 76–51(AAU)]; PENINSULAR: Krabi [Niyomdham 2857 (AAU, BKF)].
Distribution.— Indian subcontinent, Sri Lanka, Burma. Ecology.— Thickets, disturbed forest and clearings; ca 300 m alt
Notes.— Many collections of M. monosperma exist from the Indian subcontinent but only six collections (all cited above) have been seen from Thailand, five from a small part of the N and SW regions (adjacent to its few known localities in Burma) and one from much further south. It is presumed to be uncommon but this scattering of records suggests that it is also under-collected. It differs from the six other Thai species with lamellate fruit in its lamellae converging towards the centre of the pod rather than ± parallel obliquely across the pod face. It is also distinguished from most Thai species in often having conspicuous red-brown indumentum on stems and leaves, otherwise seen only in M. oligoplax (which is distinguished by fruit lamellae few and scarcely developed, pedicels, calyx lobes and flowers longer and corolla paler) and sometimes in M. macrocarpa (which is distinguished by narrower ± truncate lateral leaflets, stipels absent, long inflorescences from old wood, flowers with a pubescent apical border and long narrow woody pod). When this indumentum is absent, flowering material of M. monosperma is easily confused with M. biplicata (Peninsular Malaysia, not recorded from Thailand) which has markedly different bifurcated fruit lamellae (“T-shaped” in cross-section rather than simple) but very similar broad leaves and short inflorescence axes, short calyx lobes and short purple corolla, although calyx lobes of M. biplicata are often very indistinct, the lowest only 1.5–4 cm rather than ca 4.5 cm and laterals often < 0.5 mm.
6. Mucuna stenoplax Wilmot-Dear, Kew Bull. 47: 218 & Fig 4. 1992. Type: Peninsular Malaysia, Perlis, [Chan in FRI 19916 (holotype K!; isotype KEP)]. Figs. 1 H–J, 2 G.
Climber; stems and petioles with sparse fine, adpressed pale hairs. Leaves with terminal leaflet 9–11 by 5–7 cm, elliptic, apex gradually or abruptly short-acuminate, base broad-cuneate, lateral veins 4–5 pairs, gently curved; lateral leaflets with width ratio of abaxial to adaxial halves 1.5:1, base of abaxial half ± truncate; thin-chartaceous, with abundant but rather inconspicuous hairs like the stem beneath and sometimes above; stipels slender, 4–5 mm. Inflorescences only 2–7 cm long, main axis unbranched, ultimate branchlets