Compilation
Physotrichia arenaria

Robust perennial herb 30–200 cm. high; rootstock a hard woody rhizome; plants glabrous to somewhat glaucous, except for the petals and fruit. Stem terete, rigid, solid and with numerous rather fine grooves, sparsely branched above and sometimes tinged purple below. Leaves 5–40 cm. long, broadly triangular in outline, 2–3-pinnate; ultimate segments 2–15 mm. long, linear to filiform. Petioles very short to obsolete; the first pair of leaflets arising immediately above the large sheathing bases, which may be up to 5 cm. long with a narrow membranous margin. Leaves gradually reduced upwards, until only the sheathing base with a short 3-fid lamina is present. Inflorescence of terminal and lateral compound umbels. Bracts conspicuous, greenish to creamy white, linear with an acute apex (sometimes eroded and presenting a truncate appearance). Rays 5–16, 1.5–11 cm. long, robust. Bracteoles numerous, similar to the bracts. Partial umbels with numerous flowers on fine wiry pedicels 5–10 mm. long. Petals white, hairy on the outer surface; calyx teeth absent; stylopodium conical, with a slightly undulate base; styles spreading, later deflexed in the fruiting condition. Fruit up to 6 × 2.5 mm., cylindrical at maturity, very densely covered with white to yellowish spreading hairs which completely obscure the ribs. Endosperm curved and concave towards the commissure. Vittae 1 in each interval and 2 in the commissural face. Carpophore 2-cleft or entire, rather delicate and not persisting long after the mericarps are shed.