Alisma

Alisma lanceolatum

Family: Alismataceae.

Form: Water plant

Origin: Native of Europe, western Asia and northern Africa.

Flowers/Seedhead: Numerous with sepals about 2 mm long and petals about 4 mm long. Flowers summer.

Description: Erect aquatic perennial herb to 1 m high. Leaves variable, submerged leaves strap-like; emergent leaves with up to 7 prominent parallel veins and on a stalk to 80 cm long that is flat on one side and with small wings at the base. Aggregate fruit triangular in outline, individual 1-seeded fruit 2–2.5 mm long and falling singly.

Distinguishing features: Distinguished by emergent lanceolate leaf blades to 20 (rarely to 21) cm long and to 4 (rarely to 5) cm wide, tapering to base; large open inflorescence to 50 cm long and 30 cm wide and held higher than leaves; flowers bisexual, about 1 cm wide with 3 acute-tipped white or pink petals and 3 smaller green sepals, stamens 6 and style curved towards base; aggregate fruit with 18–20 individual fruit rounded at the end furthest from the point of attachment and these fruit in one plane.

Dispersal: Spread by seed and movement of tubers.

Confused With: Alisma plantago-aquatica which has broader leaves and Sagittariaspecies that have narrower inflorescences with flowers in whorls around the inflorescence axis.