Hornwort

[hɒ:nwә:t]

(noun.) liverworts with slender hornlike capsules.

(noun.) any aquatic plant of the genus Ceratophyllum; forms submerged masses in ponds and slow-flowing streams.

Checked by Dora--From WordNet

(n.) An aquatic plant (Ceratophyllum), with finely divided leaves.

Checked by Adrienne