What is the meaning of Pondweed?

Any of several plants that grow in ponds or similar aquatic conditions:

1. Potamogeton, a diverse and worldwide genus
2. Elodea, found in North America
3. Azolla, of cosmopolitan distribution
4. Aponogeton, in Africa, Asia and Australasia
5. opposite-leaved pondweed, Groenlandia densa, only plant of its genus, found chiefly in the Mediterranean region.

Potamogeton, a diverse and worldwide genus

Elodea, found in North America

Azolla, of cosmopolitan distribution

Aponogeton, in Africa, Asia and Australasia

opposite-leaved pondweed, Groenlandia densa, only plant of its genus, found chiefly in the Mediterranean region.

Charales, an order of green algae

Source: wiktionary.org