Arisaema pattaniense Gagnep.

Evergreen herb to 0.85 m tall. Subterranean stem a rhizome, 3–5 ×1.5–2 cm, light brown outside. Cataphylls sheathing separately petiole and peduncle, green with faint pink mottling; petiole 45–85 ×1–2 cm, olive-green with pink mottling and dark carmine stripes; leaf blade pedate; leaflets 5, elliptic, to 25 × 9 cm, margins entire, apex acuminate, ending in an arista to 3 cm long; central leaflet base cuneate, with a petiolule to 4 cm long; lateral leaflets asymmetrical, decreasing a little in size outwards, base convex, shortly petiolulate, glossy green with barely impressed veins above, underside paler. Inflorescence more or less held at foliage level; peduncle to 0.75 m long, thin, green with dark green stripes; spathe tube slightly funnel-shaped, 6–7 × ca 1 cm at the base, pale green outside and white inside, white at the base; spathe mouth margins with broad, yellow-green auricles, ca 2 cm wide; spathe limb ovate, 8–9 × 3–4 cm in the middle, glossy yellow-green, acuminate, ending in a filiform tip to 2 cm long; spadix appendix slightly exserted from the tube, erect, subcylindrical, white-green, with a rounded, even or slightly rugose apex, ca 4 cm long × 3.5 mm wide, sessile, often with a few, short carmine or green bristles above the fertile part; fertile zone staminate or bisexual, ca 4 cm long; staminate flowers 3–4 androus, subsessile, anthers cream, carmine at the top; thecae dehiscing by an oblong pore; pistillate flowers densely arranged; ovaries ovoid, pale green; stigma subsessile, capitate. Infructescence unknown.