Mucuna oligoplax Niyomdham & Wilmot-Dear

International Legume Database and Information Service

Morphology General Habit

Perennial, Climbing, Shrub

Wilmot-Dear, C.M. et al. (2019). Notes on Mucuna (Leguminosae: Papilionoideae) in Thailand: fruits of M. oligoplax re-assessed, and a revised key to species with lamellate fruits. Kew Bulletin 74: 55. https://doi.org/10.1007/s12225-019-9839-9

Type

Thailand (peninsula), Songkhla Province, Na Thawe, S of Chana, Khao Nam Khang National Park, 06°45'N, 100°43'E, 100 – 150 m, fl. & old fr., 20 Oct. 1991, Larsen et al. 42455 (holotype K! (consisting of 2 sheets: K000894897, K000894898); isotypes AAU, BKF — image! (20294), MO — image! (MO-04594911), PSU!).

Distribution

Thailand, Southern Region (Songkhla, Satun and Trang Provinces).

Ecology

Clearings and disturbed areas in evergreen dry forest, rainforest or scrub forest and along stream-sides; 60 – 200 m altitude.

Morphology General

This species is distinctive in its dark red indumentum, slightly lengthened brachyblasts, shallow simple lamellae running only from the midline of the fruit to the edges, not or scarcely oblique, and wing along the adaxial margin of fruit of markedly irregular width

Note

Mucuna oligoplax was previously known only from the type collection (Song Khla, Nathawee, Khao Nan Kaung Nat. Park, Larsen et al. 42455). M. gigantea resembles M. oligoplax in fruit shape and inflorescence architecture, differing in a much more markedly "pseudumbellate" inflorescence with more slender main axis, no purple in the corolla and a complete absence of lamellae on the fruit. M. monosperma resembles M. oligoplax in having red brown pubescence on its stems and leaves, a short main inflorescence axis, purple flowers and lamellate fruit; it differs in uniformly dark purple petals, numerous and well-developed fruit-lamellae, and often smaller leaflets (the terminal one 7 – 14 rather than 12 – 14 cm long). Mucuna monosperma DC. ex Wight (N Thailand) is the most closely similar species with red-brown indumentum, a similarly short inflorescence and fruit lamellae interrupted but due to its fruit shape (a 1-seeded, much shorter, almost ellipsoid fruit, nearly as wide as long) the lamellae all converge towards the middle of the pod; it also has shorter pedicels and corolla, shorter and broader calyx lobes, and dark (rather than pale) purple petals. Mucuna championii Benth. (China) also has reddish (but more orange-red) indumentum, and a longer 3 – 4-seeded pod (length 3 – 4 × width) with markedly oblique lamellae not or rarely interrupted. The long pedicels and slightly lengthened brachyblasts are similar to (although shorter than) those of the widespread M. gigantea which is easily distinguished by pubescence on vegetative parts pale or absent, inflorescence distinctly pseudumbellate, flowers greenish-white with shorter calyx lobes, pedicels and wing petals, no lamellae on the fruits and seeds not mottled.

Morphology Reproductive morphology Flowers

Flowers in the type collection were said to be "white tinged purple or green", but a second collection and more detailed label data for the type clarifies this as standard pale greenish or brownish purple, wing purple with darker veins and keel "whitish purple"

Morphology Reproductive morphology Flowers Pedicel

Pedicels are less uniform than previously stated, giving the inflorescence an indistinctly "pseudumbellate" appearance; in gross morphology it is thus intermediate between M. gigantea and M. monosperma which both also have oblong few-seeded fruits. Both species differ from M. oligoplax in their shorter flower-parts with flowering pedicels respectively < 2 cm and c. 1 cm long (rather than mostly 2.5 – 3.5 cm), wing-petals respectively ≤ 4 cm and ≤ 4.5 cm long (rather than c. 5 cm) and lowest calyx lobes 2 – 3 mm long (rather than 6 – 8 mm).

Conservation

Apparently rare, known so far only from two collections in Trang and Songkhla provinces in disturbed areas in evergreen rainforest. Vulnerable (VU); possibly endangered (EN).