Myriophyllum spicatum, an
introduced-from-abroad aquatic perennial herb, inhabits marshy
places. Stems extend long and branch, with four pinnatifid leaves,
2-3.5cm in length, each in whorls at nodes. Light yellow flowers set
themselves in 3-8cm-long racemes, having emerged from underwater;
male flowers position themselves on the upper parts and female
flowers on the lower portions. The flowers are 4-petaled on both
males and females. Bloom time: May-October.