Myriophyllum Aquaticum

Perennial, Water Plant, Aquatic herb, either growing in water, with most of the upper leafy parts above the water-level, or sometimes on mud; stems 0.45–1.2 m. long, simple or sparsely branched, puberulous or glabrous, with up to 1/4 emerging, mostly several from a creeping rhizome.

Perennial

Grown for folage, Flowers unisexual, monoecious or mostly dioecious, solitary in the leaf-axils, the lower flowers ♀ and the upper ♂. Male flowers:bracteoles 2, linear, 1.5–3 mm. long, 0.1 mm. wide, white, very finely bifid or trifid; pedicel and calyx-tube together at first 1.3–2.5 mm. long, tenuous, later 3.5–5 mm. long, 2 mm. thick; lobes 4, oblong-lanceolate or narrowly triangular, 0.7–1.8 mm. long, 0.4 mm. wide, at first erect, later spreading, minutely serrate; petals 4, boat-shaped, 2.5–5 mm. long, 0.8–1.3 mm. wide, clawed; stamens 4–8, filaments 0.15–5 mm. long; anthers 1.9–3.5 mm. long, 0.4 mm. wide; sometimes minute rudiments of styles present. Female flowers:bracteoles 2, 0.7–1.2 mm. long, 0.15 mm. wide, acute, sub-membranous, toothed at the middle; pedicels 0.3–0.7 mm. long, thick; calyx-tube 0.5–1 mm. long, 0.5–0.6 mm. wide, 4-angled, 4-grooved, the 4 lobes linear, (0.3–)0.5–1 mm. long, later reflexed, entire, minutely serrulate or pinnately ± 5-lobed; petals and stamens lacking; stigmas 4, short, 0.45–0.7 mm. long, later decurved, capitate or claviform, shortly papillose.

Fruit ovoid, 1.8 mm. long, 1.2 mm. in diameter, papillose-punctate, eventually dividing into 4 parts.