Calamus palustris Griff.

Moderate to robust clustering rattan. Stems climbing to 30 m long, without sheaths 0.3–3 cm diam., with sheaths 0.7–5 cm diam., internodes 15–30 cm long. Leaf cirrate; sheaths bright green, variably armed sparsely to densely with scattered, horizontal or slightly reflexed red-brown, yellow-based spines to 3 cm long, sometimes interspersed with much smaller broad-triangular dark spines, pale to reddish brown caducous indumentum usually abundant on newly emerged sheaths, sometimes distinctly striped; knee conspicuous, usually more sparsely armed than the rest of the sheath; ocrea very inconspicuous, unarmed, soon disintegrating; flagellum absent; petiole 5–30 cm long, semi-circular in cross section, the adaxial surface often armed with short erect spines; rachis to 2.5 m or more; cirrus 40–100 cm; leaflets 10–25 on each side of the rachis arranged in evenly spaced divergent pairs, a few leaflets near the base and the cirrus borne singly, the largest leaflets to 35 x 5.5 cm, rarely larger, tips somewhat cucullate, margins bristly, veins both adaxially and abaxially unarmed. Inflorescences male to 140 cm long, the female usually much shorter, to 50 cm long, lacking a terminal flagellum, the male branched to 3 orders, the female to 2 orders, partial inflorescences 8–12, close and not very well differentiated; male rachillae 2.5–5 x 0.3 cm long, female rachillae to 10 x 0.4 cm. Fruit rounded, the calyx explanate at fruit maturity so fruit appearing sessile, 0.7–1.2 x 0.7–1 cm, with a short rather triangular reddish beak to 0.15 x 0.15 cm, and covered in 17 vertical rows of white unchannelled scales. Seed c. 0.5–0.9 x 0.5–0.7 cm, ± rounded; endosperm homogeneous.