Rush
Juncus sp.
Growing in water about 5cm deep in a roadside ditch, Nairobi, Kenya. Dec 2015.
From Wikipedia: Rushes of the genus Juncus are herbaceous plants that superficially resemble grasses or sedges. They have historically received little attention from botanists. The form of the flower differentiates rushes from grasses or sedges. The small brown, often papery flowers of Juncus comprise five whorls of floral parts: three sepals, three petals (or, taken together, six tepals), two to six stamens (in two whorls) and a stigma with three lobes. The stems are round in cross-section, unlike those of sedges, which are typically somewhat triangular in cross-section. In some some of the most widespread and familiar species, the leaves are reduced to sheaths around the base of the stem and the bract subtending the inflorescence (clusters of flowers) closely resembles a continuation of the stem, giving the appearance that the inflorescence is lateral.