Bucephalandra yengiae P. C. Boyce

Small obligate rheophytic herbs to c. 10 cm tall. Stem creeping with active portion sub-erect, c. 4 mm in diam. Leaves up to 13 together; petiole 3 - 4 cm long × c. 1.5 mm in diam., adaxially narrowly canaliculate, redbrown, sheathing at extreme base, wings extended into a very narrowly triangular ligular portion to 2 cm long; blade ovate to broadly elliptic, 7 - 9.5 cm long × 3 - 4.5 cm wide, rather softly coriaceous, glossy medium green adaxially, paler yellowish greenish red abaxially, base broadly cuneate, apex acute and apiculate for c. 1.5 mm, margin usually straight; midrib abaxially and adaxially prominent, reddish abaxially; primary lateral veins c. 4 on each side, diverging at c. 45° and running to a marginal vein; interprimary veins almost invisible; secondary venation adaxially ± obscure. Inflorescence solitary; peduncle exceeding petioles, 5 - 9 cm long, conspicuously longitudinally sulcate, reddish stained. Spathe elliptic ovate, not constricted, c. 3  cm long; lower spathe funnel-form, yellow-green, shading to red at peduncle insertion, persistent; limb inflating at pistillate anthesis, then gaping to produce a slit approximately at junction of limb and lower spathe, caducous at staminate anthesis, white, acuminate, and apiculate for c. 4 mm, apiculum green. Spadix c. 1.5 cm long; pistillate zone cylindrical, c. 5 mm long × c. 3 mm in diam., with c. 4 spirals of pistils; pistils rhombic-globose, c. 0.5 mm in diam., pale green; stigma sessile, polygonal umbonate, c. ½ diameter of ovary, papillate at anthesis, pinkish; pistillodes 1 or 2 at base of pistillate zone, squat fusiform, sub-equalling pistil, white; interstice with 1 row of scale-like staminodes, these c. 1.5 mm long × c. 2 mm wide, margins reflexed, initially erect, then spreading, white, later (postanthesis) becoming green and persisting to cover developing fruit; staminate zone c. 3 mm long × c. 3 mm in diam., consisting of c. 3 rows of flowers; staminate flowers ascending, cream; stamen c. 1 mm across × c. 1.5 mm long; filament short, slender; connective slender strap-shaped; thecae inserted ventrally, completely obscuring filament, ellipsoid, c. 1 mm long × c. 0.5 mm wide, smooth; thecae horns c. ½ length of associated theca, setaceous, upwarddirected; appendix cylindrical, c. 6 mm long × c. 4 mm in diam., cream; appendix staminodes columnar, irregularly pentagonal or polygonal, 0.3 - 0.5 mm in diam., tops echinate, glossy. Fruiting spathe funnel-form, c. 1 cm in diam., with shield-shaped staminodes persistent, turning green, spent distal part of spadix falling; fruits and seeds not seen.