Root-climbing, herbaceous liana, flowering shoot not forming a leaf rosette. Internodes 4 - 9 x 0.8 - 0.9 cm, greyish and glossy in life and when dried. LEAVES: prophyll c. 22 cm long x 0.85 cm diam. in lower half, not persistent, pale green with paler striations; petiole 13 - 27 x 0.3 - 0.5 cm, green with paler striations, striations more prominent distally causing the petiole apex to be slightly rugose (the rugosities not tinged with purple as in P. ornatum), adaxial surface convex with rounded margins, abaxial surface rounded, extrafloral nectaries sparse; leaf blade ovate in outline, apex acuminate, base cordate, adaxial surface dull dark green with paler midrib, in juvenile leaves bearing greyish to silvery patches between the primary lateral veins which become inconspicuous and irregularly distributed in adult leaves, abaxial surface glossy green with distinct linear resin canals; anterior division 28 - 34 x 17.0 - 19.5 cm, primary lateral veins 8 - 9 on each side, paler than blade, with interprimary veins occurring in lower half of division; posterior divisions each 3 - 4 x 8 - 10 cm, rounded and somewhat asymmetric, primary acroscopic veins 2, primary basiscopic vein 1. INFLORESCENCE: solitary, peduncle 1.0 - 4.4 x 0.4 - 0.8 cm, slightly thicker near the spathe; spathe 13.0 - 16.5 cm long, slightly constricted, insertion long-decurrent; tube 5 - 8 cm long x 1.5 - 2.9 cm diam., externally rose-coloured with paler striations, internally greenish-cream; blade 7 - 8 x 1.2 - 1.3 cm, externally pale green with reddish extrafloral nectaries, internally greenish cream; spadix 11.3 cm long, subsessile; female zone 4.4 x 1.0 cm, subcylindric; intermediate sterile male zone 1.9 x 0.8 cm, thicker basally, fertile male zone 5.0 x 1.0 cm, cylindric, apex obtuse. Flowers: stamens 3 - 5 per flower, 2.0 x 1.25 mm; staminodes 1.75 x 1.5 mm; gynoecium 2.0 - 2.5 mm long, narrowing towards the base; ovary 1.5 x 1.25 mm, locules 3 - 4, lacking mucilaginous contents; ovules c. 15 per locule, 0.8 mm long, hemianatropous, funicle with trichomes; placentation axile but with the lowermost ovules forming a whorl; style 0.5 x 1.25 mm; stigma 0.8 - 1.0 mm wide, discoid. INFRUCTESCENCE: c. 8.3 cm long; berry 0.5 - 0.55 x 0.2 - 0.3 cm, cream-coloured; seed 1.0 x 0.5 mm.