Myriophyllum gracile var. lineare

Perennial aquatic or semi-aquatic herb, sometimes dioecious; stems slender, erect, 5–20 cm tall, mostly c. 1 mm diam., rooting mainly at the base. Leaves alternate, 5–8 mm long; lower leaves linear to narrow-lanceolate, often shortly toothed; upper leaves entire. Bracteoles linear to ovate, 0.3–0.6 mm long; flowers solitary, male and female flowers on same spike, or often, female flowers alone. Male flowers sessile; sepals 4, linear-lanceolate, 0.4–0.5 mm long, erose; petals 4, 2–2.5 mm long, creamy-yellow with red tip; stamens 8. Female flowers sessile or subsessile; sepals and petals absent; ovary 4-celled, styles elongating and reflexing, stigmas white. Fruit cubiform, yellow-brown to deep reddish-brown; mericarps cylindric, 0.5–0.7 mm long, smooth or papillose in lower half, often with an apical rim.  Flowers mainly in spring.