Elodea canadensis Michx.

Vigorous dioecious perennial. Stems slender, branched, very brittle, to 6 m long, c. 1 mm diam. Leaves opposite below, crowded and in whorls of 3 above, 6–12 × c. 2 mm, oblong or ovate-oblong, subobtuse, translucent, margins minutely toothed. All N.Z. collections, with exception of 2 from Hawkes Bay, have been from female plants. Flowers 1 per spathe in axils of upper leaves; male flowers with broad green, purple-striped sepals and narrow petals; female flowers with small, green, purple-spotted sepals and white petals ± 2.5 mm long, on perianth-tube to 20 cm long. Capsules not present in N.Z.

[From: Healy and Edgar (1980) Flora of New Zealand. Volume 3.]

Flowering: Nov.–Jan.