Potamogeton distinctus A.Benn.

Habit

Perennial aquatic herb

Family Description

Perennail aquatic herbs, usually with creeping rhizomes in substrate, and erect, flexible, leafy shoots in water; accasionally semi-terrestrial. Leaves alternate, the upper sometimes opposite, subtended at base by membranous stipules, bases sometimes sheathing, submerged leaves usually narrow, floating leaves with expanded blades sometimes also present. Flowers whorled, in cylindric spikes on axillary peduncles; 4-merous, bisexual, ebracteate, with 4 greenish claw-shaped tepals; stamens 4; carpels 1-4 developing into druplets containing a single curved embryo.

Genus Description

Perennail aquatic herbs, usually with creeping rhizomes in substrate, and erect, flexible, leafy shoots in water; accasionally semi-terrestrial. Leaves alternate, the upper sometimes opposite, subtended at base by membranous stipules, bases sometimes sheathing, submerged leaves usually narrow, floating leaves with expanded blades sometimes also present. Flowers whorled, in cylindric spikes on axillary peduncles; 4-merous, bisexual, ebracteate, with 4 greenish claw-shaped tepals; stamens 4; carpels 1-4 developing into druplets containing a single curved embryo.

Species description

Overwintering as condensed sympodial rhizome system with slender, acute, lateral buds. Stem to 30cm, simple. Leaves all floating, upper usually opposite, variable in shape, elliptic or narrowly elliptic, obtuse to acute, base truncate (to cuneate), 3-5.7(-8.5) x (1-)1.5-3.1cm, shorter or longer than petiole, with 11-19 longitudinal veins and many fine cross-veins visible against light, coriaceous. Stipules mostly decayed at flowering, acute, to 3cm. Peduncle tapering very slightly upwards, 3.8-7cm. Spike dense. Carpels 1-2 per flower. Drupelets 3-4mm long, usually with tubercle only at base, ventral face curved, dorsal face semicircular, beak less than 0.5mm.