Scientific name: Potamogeton polygonifolius Pourr.
Common name: Bog Pondweed
Description
Habit: Aquatic perennials. 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, long-stalked, thinner and more membranous, sometimes absent; floating leaves as in P. natans, but somewhat narrower; stipules membranous with well-separated, slender veins, 2.5-3.5cm long.
Flowers: In spikes or heads, spike dense, 25-35mm long; peduncle much longer, slender; 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, 1.5-2.6mm, greenish, with thick pericarp, soft on outside but with bony inner layer.
Habitat: Bog-holes, drains, lakes and wet, peaty ground.
Distribution: Abundant except on limestone soils.
Native status: Native
Of conservation interest: No