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.
As described by Withering this species, regarded as a variety only of the common Water Plantain, has the leaves lance-shaped, narrowed below. The sepals are ovate, and the styles are as lor.g as the ovary. The capsule is 3-angled. The leaves are nearly strap-shaped, with no distinct leaf-stalk. The habitat is ditches, shallow water.
The habitat of this plant is lakes, and the plant is very rare. The stem is floating and rooting, slender, often very long, leafy, and gives rise to long-stalked, oblong, floating leaves, and 1-5 slender, erect, flowered, simple stalks, the upper sometimes in an umbel. The radical leaves are submerged, stalkless, membranous, linear, awl-like. The radical leaf-stalks are broadly awllike. The root petioles are in small tufts. The floating leaves are elliptic, stalked, oblong, blunt. The flowers are white, with a yellow spot or claw, large. The carpels are finely furrowed, and beaked. The plant is partly floating. It flowers in July and August, and is a herbaceous perennial.
Star Fruit or Thrum Wort(Damasoniumahsma, Mill. = D. stellatum, Pers. = Actinocarpus Dama-sonitim, Sm.). - The habitat of this plant is ponds and ditches, gravelly ditches, and pools. The leaves are numerous, radical, floating or submerged, long-stalked, heart-shaped below, elliptic, narrow to oblong, 5-veined, blunt. The leaf-stalk is stout. The scape is stout and bears 1-3 whorls of flowers, which are white, with petals that soon fall. The carpels are large, awl-like, flattened, opening longitudinally, star-shaped. The seeds are 2, stalked, one erect, the upper horizontal. The plant is 4-12 in. in height, flowering between May and July, and is a herbaceous perennial.