Flora of New Zealand Series

Stout perennial herb; stems to 30 cm tall, prostrate to erect. Lvs all whorled, slightly dimorphic. Submerged lvs often decaying early, in whorls of 5-7. Aerial lvs yellow-green to subglaucous, crowded towards tips of stems, spreading, in whorls of (4)-5-7, oblong, (15)-20-35 × (4)-6-10 mm, becoming smaller near water surface, pectinate, with 26-32 filiform to linear pinnae. Fertile aerial lvs similar to other lvs. Fls ⚥. Bracteoles ovate to orbicular, 0.7-0.8 × 0.7-0.8 mm. Sepals 4, ovate to deltoid, 0.6-0.8 × 0.5-0.6 mm; petals 4, weakly hooded, 2.5-3.4 × 1.1-1.2 mm. Frs globular to slightly obturbinate, 1.5-2 (excluding sepals) × 2-2.5 mm, with a few small tubercles on keel of mericarps.

N.: N. and S. Auckland, Hawke's Bay, Wellington; S.: West Coast, also 2 early records from Mt Arthur (Nelson) and Awatere (Marlborough).

Endemic.

Aquatic or terrestrial, mostly swamps and slow-flowing streams, now apparently much less common than formerly.