Scientific name: Potamogeton obtusifolius Mert. & W.D.J. Koch
Common name: Blunt-leaved Pondweed
Description
Habit: Aquatic perennials. Stem only slightly compressed. Rhizome absent; winter buds terminating lateral branches, leafy. Hybrids are rather frequent in this genus.
Leaves: Leaves mostly alternate, some opposite, submerged, subtending inflorescences, all with membranous sheath or stipules; submerged leaves broadly linear, 2.5-3.5mm wide, obtuse, stalkless, often somewhat crowded near the tip of the stem; the lateral veins faint, the midrib with or without a narrow border of lacunae; stipules open, convolute, membranous, 1-3cm long.
Flowers: In spikes or heads; spikes 5-10mm long, peduncles twice as long, 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, 2.6-4mm, with a sharp dorsal keel, with thick pericarp, soft on outside but with bony inner layer.
Habitat: Ditches, pools and bog-drains.
Distribution: Occasional.
Native status: Native
Of conservation interest: No