A robust herb, about 3 ft. high
Stem and branches succulent, fistular, narrowly sulcate and ribbed.
Fruit broadly ovoid, ± 2 × 1.25 mm., glabrous, primary ribs pale and prominent; vitta solitary in each vallecula and 2 on the commissural face; stylopodia shortly conical, not or scarcely exceeded by the rather rigid, divergent, ± 0.5–0.7 mm. styles.
Coarse erect, rhizomatous perennial, rooting at the lower nodes, ± 0.6–1.5 m., moderately branched from the base upwards.
Sepals small but obvious, subulate.
Petals white to pale- or greenish-yellow, glabrous, ± 1 mm.
Leaves simply pinnate; lowest leaves with the lamina broadly lanceolate-oblong in oudine, up to ± 50 × 25 cm.; leaflets in mostly 10–15 pairs, narrowly lanceolate to lanceolate, ± 6–13 × 0.8–4 cm., acute to rather blunt at the apex, occasionally with a small lobule on the basal antical margin, the margins regularly and neatly denticulate, each tooth with a white mucro which is incurved and frequendy overlapping the base of the next tooth above; sheath oblong, abrupdy narrowed and auriculate on each side above, striate, membranous-margined, ± 4–11 cm. long; leaves all sessile on the sheaths; upper leaves rapidly much reducing with fewer and narrower leaflets, as finely denticulate as the lower.
Umbels on 2–9 cm. peduncles; rays ± (10–)15–50, unequal, 0.8–6 cm.; involucre conspicuous, of ± 8–12 linear and entire to ternate or pinnate ± 0.8–2 cm., pale-margined bracts; partial umbels ± 12–40-flowered, pedicels 2–6(–8) mm.; involucel similar to the involucre, of 8–12 simple or occasionally bi- or trifid bracteoles 3–5 mm. long.
Stems terete, hollow, strongly grooved, sometimes tinged with red.
Stem leaves up to 30 cm. long, simply pinnate with narrowly oblong-lanceolate leaflets up to 10 × 2 cm.; leaf-bases with well-developed auriculate membranous sheaths; petiole and rhachis terete, hollow except at the point of attachment of the leaflets; apices acute, with a short cartilaginous mucro; margins with regular serrations, cartilaginous, the fine points incurved over the base of the next tooth.
A coarse, glabrous perennial herb up to 1·5 m., with a creeping rhizome.
Vittae 1 in each interval and 2 in the commissural face; seed conforming to the shape of the fruit.
Fruit c. 2 × 1 mm., ovate-oblong, truncate below the stylopodium, reddish-brown when ripe, slightly laterally compressed; calyx teeth minute. Stylopodium conical; styles 0·5 mm. long, stiff and divergent, stigmatic surfaces slightly enlarged. Carpophore stiff, undivided or slightly 2-fid. Primary ribs filiform, secondary not developed.
Flowers all hermaphrodite, 20–30 in each partial umbel, on irregular rays 2–8 mm. long.