This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Sparganium neglectum, Beeby( = S. erectum, L.). - The habitat of this plant is wet places. It has been regarded as a variety of 5. ramosum. The inflorescence is, however, less branched and spreading. The stem is branched above. The radical leaves are 3-angled below. The perianth-segments of the female flowers are narrow, 1-nerved, the tip enlarged. The stigma is linear to lance-shaped. The ripe fruit is oblong to inversely ovoid, with obscure angles narrowed gradually into a long tapering beak. The plant flowers from June to August, and is a herbaceous perennial.
The habitat of this plant is ditches and streams, ponds, river-banks. The plant is erect in habit or ascending. The stem is simple. The leaves are 3-angled at the base, keeled, erect, long, floating, with flat sides. The heads are numerous, racemose. The male heads are several, yellow, stalkless. The female are stalked, especially below. The stigma is linear, awl-like. The fruit is a drupe, shortly-stalked, more or less spindle-shaped, elliptic, narrowed both ends. The beak is long. The seeds are smooth. The plant is 1-3 ft. high, flowering in July and August, and is a herbaceous perennial.
The habitat of this plant is lakes, ditches, pools. The habit is as in the last. The stem is simple, limp, rather thick, sub-erect in flower, leafy, floating above. The leaves are floating, flat at the base, not keeled, long, linear, limp, the base swollen, sheathing, concave, grass-green. The heads are racemose, numerous, distant, stalked, the lower fertile ones, the male heads numerous, stalkless. The stigma is tongue-shaped, linear to lance-shaped. The fruit is a drupe, stalked, oblong, not longer than the beak, which is long, awl-like, spindle-shaped. The plant is 1-3 ft. long, flowering in July and August, and is a herbaceous perennial.
The habitat of this plant is lakes and ditches. The stem is simple, limp, slender. The leaves are linear, floating, blunt, not swollen below, pale, long, transparent.
The heads are few, racemose, or in spikes, distant. There is a solitary male head. The lower female heads are shortly-stalked. The stigma is short, oblong to lance-shaped. The fruit, a drupe, is stalkless, inversely ovoid, shortly-beaked. The plant flowers in July and August, and is a herbaceous perennial.
The habitat of this plant is ditches, ponds, stream-sides, lakes. The plant is erect in habit. The stem is slender. The leaves are linear, convex, channelled below, dark-green, narrow, longer than the inflorescence. The spikes are separated by 1/2-3/4 in., the males above, the female below, the female reddish-brown, interrupted, with bracts. The perianth-scales are enlarged towards the top. The style is longer than the bristles. The style is long and slender. The rachis is hairy. The fruits are stalked with silky hairs. The plant is 5-7 ft. in height, flowering in June and July, and is a herbaceous perennial.