Aridarum uncum P. C. Boyce & S. Y. Wong

Medium-sized obligate clumping to stoutly-creeping rheophytes 20 – 25 cm tall. Stem condensed, suberect, later to c. 35 cm long × c. 2.5 cm in diam. with copious strong roots and conspicuous triangular buds with an associated petiole scar. Leaves up to 6 together, petioles suberect with blades arching; petiole 6 – 8 cm long × c. 3 mm in diam., terete and distally weakly dorsally channelled, sheathing at the extreme base, medium green; petiolar sheath with wings extended into a narrowly triangular ligular portion 5 – 8 cm long, ligule persistent, eventually shed to leave incurved, folded margins of the sheath; blade softly coriaceous, elliptic to oblanceolate, 14 – 20 cm long × 7 – 9 cm wide, base cuneate or slightly decurrent, apex acuminate, apiculate for c. 3 mm, adaxially semi glossy dark green, slightly paler abaxially; midrib abaxially prominent until c. half way along the blade, adaxially slightly raised for the first third of the blade, thereafter sunken; primary lateral veins c. 6 on each side, barely discernible, diverging at c. 30°; interprimary veins slightly weaker than the primaries; secondary venation adaxially invisible, abaxially forming a slightly darker reticulum. Inflorescence solitary, subtended by a 9 – 13 cm long, very narrowly triangular somewhat leathery two-keeled cataphyll; peduncle very slender, arching with the inflorescence pendent, exceeding the petioles, 9 – 11 cm long × 2 – 2.3 mm in diam., terete, medium green; spathe broadly lanceolate, not constricted, 6 – 11 cm long, lower part narrowly campanuliform at anthesis, pale green, ultimately persistent through fruiting, limb glistening white, apiculate for up to 13 mm, apicule green; limb loosening at pistillate anthesis but hardly opening, prior to and during staminate anthesis deliquescent and crumbling from the junction of the spathe limb and the persistent lower part, limb tearing into jagged adherent strips that eventually fall to leave a brown slimy collar of decomposing tissue that this later rots and falls to leave the narrowly campanuliform persistent lower spathe, with a scarred irregular rim. Spadix subcylindric 3 – 6 cm long × 6 – 7 mm in diam. (widest part); pistillate flower zone slender cylindric. Markedly thinner than the rest of the spadix, comprising c. 1/4 of the spadix, obliquely inserted on peduncle, zone c. 3.5 mm in diam., ventral side 8 – 12 mm long, dorsal side 4 – 9 mm long, with an a few c. 1.5 mm long clavate-vermiform glossy white, yellow-tipped staminodes at the base; pistils compressed-globose, c. 1 mm in diam., pale green; stigma sessile, slightly impressed, discoid, papillose, slightly less wide than ovary, greyish; sterile interstice slender cylindric, abruptly truncate with the top of the pistillate zone, c. 3.5 mm long, with 3 or 4 dense whorls of staminodes; interstice staminodes well-developed, clavate with a cordate-triangular to horseshoe-shaped head, with the arms of the horseshoe directed towards the base of the spadix, c. 2.5 mm wide, initially equalling the staminate zone in width, later (at staminate anthesis) staminodes expanding laterally by extension of the filament until zone 5 – 7 mm wide; staminate flower zone c. 1/2 of total spadix length, 8 – 17 mm long × 4.5 – 6 mm wide, cylindrical, basally merging with the interstice and apically merging with the appendix; staminate flowers each comprised of a single stamen, ivory, ± horseshoeshaped in plan view, c. 1.5 × 1.5 mm, connective smooth, shiny; thecae ellipsoid, imperceptibly embedded in the ends of the ‘arms’ of the horseshoe-shaped connective, each c. 0.4 mm long, displaced to the proximal (with respect to the spadix axis) side of the stamen with distalpointing horns; thecae horns c. 1.3 mm long, stiff, white, directed upwards during pistillate anthesis, reflexing to point outwards or somewhat downwards at staminate anthesis, and then producing a droplet from the tip; appendix 10 – 13 mm long, usually comprising slightly more than 1/3 of the entire spadix, conic-cylindrical, obtuse; appendix staminodes mostly comprised of densely-packed free or partially coherent papillate-tipped cylindrical staminodes, lowermost staminodes closely reminiscent of staminate flowers but lacking thecae horns, terminalmost few more laxly arranged, ivory. Infructescences pendulous. Fruiting spathe narrowly campanuliform, c. 1.5 cm long × c. 1 cm wide, pale green with a scar along the rim; persistent staminodes initially white, later becoming green; fruits and seeds not seen.