This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
As a typical aquatic form this plant is found in Preglacial beds in Norfolk and Suffolk, Interglacial beds at West Wittering, Sussex, late Glacial and Neolithic beds. It is found to-day in the N. Temperate Zone in Europe, N. Asia, N. Africa, and N. America. It is commonly found in every part of Great Britain except in Cardigan, E. Sutherland, up to the Shetland Isles, and up to 1200 ft. in Derbyshire. It is found in Ireland and the Channel Islands.
Bur-reed is one of the features of aquatic vegetation. It grows in a continuous fringe with sedges, flags, and reeds along the sides of a river or stream. It forms beds in the shallow parts, helping to choke up the bed and to divert the course of a stream. It also grows widely in ponds, lakes, and pools, which again it assists in silting up, forming part of the reed swamp.
The rhizome or underground stem is strong, creeping, the roots fibrous. The culm is erect, glabrous or smooth, leafy, branched. The leaves are triangular at the base, the radical leaves twice as long as the stem, sheathing with hollowed margins, in two rows, keeled. There are four leaflike bracts.
The plants are monoecious, and the flowers are stalkless, the male olive-brown, falling, the lower ones female, 1-3, in spiked branched heads. The fruit is a drupe with a short beak, egg-shaped, stalkless, with linear stigma, angular below. The flower-stalk is branched.
Usually Branched Bur-reed is 18 in. to 2 ft. high. The flowers bloom in July and August. A herbaceous perennial, the plant is propagated by seeds.
Photo. B. Hanley - Bur-Reed (Sparganium ramosum (Curt.) = S. erectum)
The stigma ripens first, and self-pollination is avoided. The flowers are pollinated by the wind. The flowers are in spherical heads, the male above. There are 3-6 stamens, which are alternate with 3-6 perianth-scales, and the connective is scarcely produced. The stigma is linear. The anthers open laterally. The female flower consists of 1-2 carpels, 1 ovule, pendulous near the base of the ovary.
The fruits are drupes which fall when ripe to the earth or water, being thus dispersed. A few may be dispersed by birds.
Branched Bur-reed is aquatic, and a peat-loving plant growing in peat soil or in water half-submerged.
Several beetles, Telmatophilus sparganii, T. schonherri, Donacia vulgaris, D. cinerea, Lepidoptera, Gold Spot (P/usia festucae), Nonagria sparganii, Orthotaelia sparganella, and a fly, Simulia reptans, are found on it.
Sparganium, Dioscorides, is from the Greek sparganon, band, from the long narrow leaves, and erectum refers to the upright flower-heads.
Some names given to the plant are Bede-sedge, Bur-flag, Bur-reed, Reed Grass, Knop Sedge, Seg or Seggs, Seggin. The first name refers to the large beadlike fruits, as also does Bur-reed.
Essential Specific Characters:310. Sparganium erectum, L. - Stem erect, branched above, leaves triquetrous below, side concave, male flowers in heads, brown, sessile, upper heads barren.