Curled Pondweed

crispus: with a wavy or curled margin

Herb 50-150 cm high, from a rhizome; stems 4-angled. Stipular sheaths 10-20 mm, convolute, early deciduous. Leaves 30-90 × 8-15 mm, linear-lanceolate, sessile, all submerged, shining, translucent; apex obtuse, apiculate; margin finely serrate, markedly undulate when mature. Spikes 5-10-flowered, somewhat lax. Drupe 2-4 mm, ovoid-acuminate, laterally flattened; beak nearly as long as fruit, falcate, tapered.

North Africa, Sudan, Ethiopia, Botswana, Malawi, Mozambique, Zambia, Zimbabwe and South Africa. Also in Europe, Asia and Australia. Introduced from Canada to Argentina and in New Zealand.