Cattail and Swamp plant

Cattail noun - Tall erect herbs with sword-shaped leaves; cosmopolitan in fresh and salt marshes.

Swamp plant and cattail are semantically related. In some cases you can use "Swamp plant" instead a noun "Cattail".

Swamp plant noun - A semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath.

Cattail and swamp plant are semantically related. Sometimes you can replace term "Cattail" with "Swamp plant", this terms are similar.