Branched bur-reed is an aquatic emergent plant that grows rooted in the mud at the margins of waterbodies (4). The narrow, smooth and keeled leaves are erect and triangular in cross-section (2). The globular flowers are produced on a branching spike hence the name ‘branched’ bur-reed. Flowers at the tip of the spike are male whereas those further down are female (4). The female flowers take on a bur-like appearance before breaking up into distinct fruits (5). The fruits are small, dry and spongy and contain 1-2 seeds (4).
Branched bur-reed is a perennial species that flowers from June to August (1). The leaves arise from rhizomes and die back at the end of each year (4). Although insects do visit the flowers, they are only attracted to male flowers, and so pollination by insects is not important. Pollination is mainly by wind, although self-fertilisation may occur. The fruits can float for a number of months, which aids in their dispersal. They germinate under water, but seedling survival is poor. The plants can also spread (by vegetative reproduction) from the rhizomes (6).
This native bur-reed is widespread throughout Britain, reaching altitudes of 425 m (3). It is absent from Shetland (2). It is also found in most northern temperate areas of the world (2), but is absent from eastern North America (3).
Typically found growing in a narrow band at the margins of lakes, rivers, streams, ditches and canals. Occasionally, large clumps of branched bur-reed may occur in swampy habitats. Cattle graze on this species, and so it is unusual to find branched bur-reed on banks where livestock graze (3).
Plants that live for at least three seasons; after an initial period they produce flowers once a year.
Rhizomes are thickened, branching, creeping storage stems. Although most rhizomes grow laterally just along or slightly below the soil's surface, some grow several inches deep. Roots grow from the underside of the rhizome, and during the growing season new growth sprouts from buds along the top. A familiar rhizome is the ginger used in cooking.
Vegetative reproduction (or propagation)
Type of asexual reproduction (reproduction without recombination of genetic material) that results in the propagation of plants using only the vegetative tissues such as leaves or stems. The resulting plant is genetically identical to the original plant. A well-known example of this is the reproduction of strawberry plants from ‘runners’.
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