Caltrop and Hydrophyte

Caltrop noun - A plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits.

Hydrophyte and caltrop are semantically related. In some cases you can use "Hydrophyte" instead a noun "Caltrop".

Hydrophyte noun - A plant that grows partly or wholly in water whether rooted in the mud, as a lotus, or floating without anchorage, as the water hyacinth.

Caltrop and hydrophyte are semantically related. Sometimes you can replace term "Caltrop" with "Hydrophyte", this nouns are similar.