Flora of New Zealand Series

swamp willow weed

Annual or short-lived perennial herb, glabrous or glabrate; stems prostrate or decumbent, rooting at the lower nodes, sparingly branched; roots rather slender. Lvs on main stems and branches similar; petioles short or lvs subsessile. Lamina to 15 × 4 cm, lanceolate, often with dark markings above, entire or minutely serrulate, glabrous or sometimes with appressed hairs on midrib above and below, copiously dotted with glands below; margins appressed-ciliate; base cuneate to rounded; apex acuminate. Ochreae c. 1.5 cm long, green or pinkish, obliquely truncate, not flared towards apex, long-ciliate. Fls 1-4 in whorls forming simple or few-branched, terminal or axillary racemes; racemes erect or slightly curved, 1.5-8 cm long, sometimes very slender and whorls distant, sometimes wider, cylindric, and densely flowered; peduncles slender, > upper lvs; pedicels enveloped or slightly exserted from bracts; bracts truncate, ciliate or glabrous. Perianth 2-2.5 mm long, deep pink to whitish, eglandular, accrescent; segments ± elliptic, imbricate. Nut 1.7-2.5 mm long, biconvex to almost plano-convex, blackish, ± glossy.

N.; S.: from near North Cape to Southland.

Also indigenous to Australia and Norfolk Id.

Swamps, lakesides, streamsides, and similar habitats with still or slow-moving water.

FL Nov-Apr.

Possibly poisonous (Connor 1977).

In N.Z. there are 2 main forms of P. salicifolium. The commonest and most widespread has very slender infls with at least the lower fls distant, whereas the other is restricted to northerly areas and has densely arranged fls on a shorter and stouter spike.

This sp. was treated by Allan (1961) as P. decipiens R. Br., although the earlier name, P. salicifolium, has priority.