Scientific name: Potamogeton alpinus Balb.
Common name: Red Pondweed
Description
Habit: Aquatic perennials. Plant often tinged with red. Hybrids are rather frequent in this genus.
Leaves: Leaves mostly alternate, some opposite, submerged or floating (rarely aerial on marshy ground), subtending inflorescences, all with membranous sheath or stipules; submerged leaves lanceolate to narrowly elliptic, up to 22 x 3.3cm, obtuse at apex, all except the upper ones sessile; floating leaves, if present, more or less translucent, elliptic to rather narrowly so, up to 9 x 2.5cm, stalked, somewhat leathery; stipules large and conspicuous, 2-4cm long.
Flowers: In spikes or heads; spike dense, 20-35mm long; peduncle 2-4 times as long, not swollen below the spike; usually borne above the water-surface; perianth of 4 free, greenish segments; carpels usually 4, free; stamens 4, anthers stalkless, attached to the base of the adjoining perianth-segment.
Fruits: Drupes or achenes, 1 or more present, 2.5-3.7mm, reddish-brown, with a sharp dorsal keel, with thick pericarp, soft on outside but with bony inner layer.
Habitat: Lakes and slow rivers, usually in fairly shallow water.
Distribution: Occasional in the North half, rather rare in the South.
Native status: Native
Of conservation interest: No