Myriophyllum amphibium

Perennial marsh, semi-aquatic or emergent herb; stems mat-forming, rooting at the nodes, tips erect, to 7 cm tall, c. 1 mm diam. Leaves opposite, broad-lanceolate to obovate, with a terminal gland, 5–25 mm long, subfleshy, margins entire or rarely with 1 or 2 lobes or teeth. Bracteoles usually linear to lanceolate, 0.7–0.8 mm long; flowers solitary. Male flowers sessile or shortly pedicellate; sepals 4, lanceolate to oblanceolate or ovate to obovate, 0.8–1 mm long; petals 4, 1.8–2.5 mm long, red; stamens 8. Female flowers sessile; sepals triangular, c. 0.4 mm long; petals absent; ovary 4-celled, styles cylindric, becoming reflexed, stigmas red, fading to white. Fruit cylindric, purplish-black; mericarps more or less tear-drop-shaped, 1.1–1.2 mm long including style, sparsely warty-papillose. Flowers Nov.–Mar.