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

Medium-sized obligate clumping rheophytes 15 – 25 cm tall. Stem condensed, suberect, later to c. 10 cm long × c. 1.5 cm in diam. with copious strong roots. Leaves up to 15 together, petioles suberect with blades arching; petiole 5 – 14 cm long, laterally somewhat compressed, c. 2 mm wide × c. 3 mm high, distally weakly dorsally channelled, with the edges slightly raised and rounded, sheathing at the extreme base, medium green; petiolar sheath with wings extended into a narrowly triangular ligular portion 5 – 8 cm long, ligule persistent; blade softly coriaceous, elliptic, 14 – 16.5 cm long × 5 – 5.5 cm wide, base cuneate, apex acute to slightly acuminate, apiculate for c. 5 mm, adaxially semi glossy medium to dark green, slightly paler abaxially; midrib abaxially prominent until c. halfway along the blade, adaxially slightly sunken with the halves of the leaf blade arising at c. 10°, with 4 or 5 adaxially prominent primary lateral veins on each side, these diverging at c. 30°; interprimary veins roughly equalling the primaries in appearance; secondary venation adaxially invisible, abaxially forming a slightly darker reticulum. Inflorescence solitary, subtended by a 8 – 11 cm long, very narrowly triangular somewhat leathery cataphyll; peduncle very slender, arching with the inflorescence pendent, exceeding the petioles, 9 – 15 cm long, 2 – 2.3 mm in diam., terete, pale glaucous green, inserted ventral-obliquely on the spathe; spathe broadly ovate, not constricted, barely opening at pistillate anthesis, 6 – 7 cm long, lower part narrowly campanuliform at anthesis, weakly gibbous ventrally, pale glaucous-green, ultimately persistent through fruiting, limb glistening white, apiculate for up to 7 mm, apicule distally green; limb loosening at pistillate anthesis, 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 – 4 cm long × c. 6 mm in diam. (widest part); pistillate flower zone slender cylindric, markedly thinner than the rest of the spadix, comprising c. ¼ of the spadix, slightly obliquely inserted on peduncle, zone c. 3.5 mm in diam., ventral side 6 – 9 mm long, dorsal side 4 – 6 mm long, with an single row of c. 1.5 mm long clavate-vermiform glossy white staminodes at the base; pistils trapezoid-subglobose, truncate, c. 1.1 mm in diam., ivory; stigma sessile, slightly impressed, discoid, papillose, only slightly less wide than ovary, cream; sterile interstice slender cylindric, abruptly truncate with the top of the pistillate zone, c. 2 mm long, with several dense whorls of staminodes; interstice staminodes well-developed, clavate with a horseshoe-shaped head, with the arms of the horseshoe directed towards the base of the spadix, c. 1.5 mm wide, initially interpistillar zone equalling the staminate zone in width, later (at staminate anthesis) staminodes expanding laterally by extension of the filament until zone c. 6.5 mm wide and blocking access to the pistils; staminate flower zone c. 1/4 of total spadix length, 7 – 9 mm long × c. 5.5 mm wide, cylindrical, basally merging with the interstice and apically merging with the appendix; staminate flowers each comprised of a single stamen, ivory, ± horseshoe-shaped in plan view, with a conspicuous deep narrow suture between the thecae, c. 1.5 × 1.5 mm, connective with the inner part slightly channelled, smooth, and the distal margins (with respect to spadix axis) verruculose; thecae ellipsoid, imperceptibly embedded in the ends of the ‘arms’ of the horseshoe-shaped connective, each c. 0.3 mm long, displaced to the proximal (with respect to the spadix axis) side of the stamen with distal-pointing horns; thecae horns c. 0.5 mm long, stiff, translucent except for the base, directed upwards; appendix 10 – 16 mm long, usually comprising slightly more than ½ of the entire spadix, cylindrical, obtuse; appendix staminodes mostly comprised of very densely-packed circular and partially coherent verruculose brain-like staminodes, lowermost staminodes closely reminiscent of staminate flowers but lacking thecae horns, terminal-most few more laxly arranged, medium yellow. Infructescences pendulous. Fruiting spathe narrowly campanuliform, c. 3 cm long × c. 1.5 cm wide, pale slightly glaucous-green with a ragged scar along the rim; persistent staminodes initially glossy white, later becoming green; immature fruits prismaticglobose, c. 2 mm tall and in diam.; stigmatic remains sunken; ripe fruits and seeds not seen.