Homalomena prolixa S. Y. Wong & P. C. Boyce

Herbs lithophytic, perennial, erect, to c.  20  cm tall, vegetative tissues strongly aromatic of celery. Stem pleionanthic, erect, highly congested, internodes to 0.5 cm long × c. 1 cm in diam. Modules subtended by a recurved 2-keeled prophyll c. 5 cm long × 1 cm wide. Leaves up to 15 together, spreading; petiole 10 – 12 cm long × c. 3 mm in diam. (terete portion of petiole distal to petiolar sheath), semi-glossy green with irregular darker streaks, basal dorsal portion (equivalent to ventral lowermost part of sheathing portion) of petiole slightly serrate-carinate; petiolar sheath wings spreading almost flat, 5 – 6.5 cm long × c. 1 cm wide, c. 1/2 length of petiole, wings long-persistent, rather membranous, slightly unequal, pale green with darker green veins; leaf blade broadly elliptic to somewhat ovate, 10 – 15 cm long × 5 – 6.5 cm wide, somewhat coriaceous, pale green abaxially, semi-matt dark green adaxially, base cuneate, apex acuminate and mucronate for c. 2 mm; midrib rounded-raised abaxially, particularly in portion of blade proximal to petiole, adaxially ± flush with blade, up to 3 mm wide; primary lateral veins c. 4 on each side, diverging at 35° from midrib, abaxially flush with and slightly darker than blade, adaxially flush with blade and scarcely differentiated; interprimary veins c. ½ width of primary lateral veins, irregularly interspersed between primaries, abaxially somewhat darker-pellucid and broken, adaxially flush with blade; secondary venation striate, almost invisible on both surfaces of blade; tertiary venation invisible; all veins running into a slightly thickened intramarginal vein. Inflorescences up to 6 together in a simple synflorescence, each subtended by a small narrowly triangular 2-keeled prophyll, erect at anthesis, later declinate; peduncle to c. 5 cm long × c. 3 mm in diam., expanding at insertion of spathe and there c. 5 mm wide, medium green. Spathe thinly stiff, with a distinct constriction between lower portion and spreading limb, tightly furled prior to anthesis, 6 – 7.5 cm long × c. 2 cm wide at anthesis, semi-glossy pale green externally, internally glossy greenish white; lower spathe broadly ovoid, c. 2.5 cm long × c. 2 cm in diam.; limb narrowly elliptic, somewhat hooded at anthesis, 4 – 5.5 cm long with a reflexed terminal mucro c. 10 mm long; lower spathe inflating and spathe limb gaping at pistillate anthesis, spathe limb opening wide at staminate anthesis and spadix extending and flexing at interstice to protrude from spathe; spathe later closing to re-enclose spadix. Spadix 5.5 – 6 cm long × c. 7 mm in diam., stipitate; stipe c. 2 mm long, pale green; pistillate flower zone weakly fusiform, c. 1/4 length of spadix, c. 2 cm long; pistils of lower 3/4 of zone quite crowded, upper 1/4 with spirals separated by flexing/extension of interstice, upper two spirals with pistils alternating with stout staminodes, pistils globose, c. 1.5 mm tall × c. 1 mm in diam., pale green, stigma capitate, wider than pistil, c. 1 mm tall × 1.5 mm in diam., semi-translucent, glossy greenish; interpistillar staminodes irregularly globose, on a slender stalk with an expanded top, ivory; sterile interstice c. 2.5 mm long post-extension, mostly naked, pale green, with c. 2 whorls of staminodes, those of lowermost whorl of similar structure to, but larger than (c.  2  mm in diam.), those associated with uppermost pistils, staminodes of uppermost whorl resembling staminate flowers, c. 2 mm in diam., ivory; staminate flower zone narrowly fusiform-cylindric, c. 3/4 length of spadix, exserted from lower spathe chamber, 3.5 – 5 cm long × 5 – 7 mm in diam., apex bluntly acute, yellowish ivory; staminate flowers mostly densely arranged, but lowermost 3 whorls slightly lax, trapezoid to sub-hexagonal in plan view, each flower consisting of 4 stamens. Infructescence with spathe remaining green. Fruits not observed.