tape grass vs water plant

tape grass and water plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
tape grass	Yes	No	No	No
water plant	Yes	No	No	No

As nouns, water plant is a hypernym of tape grass; that is, water plant is a word with a broader meaning than tape grass:

tape grass: submerged aquatic plant with ribbonlike leaves; Old World and Australia
water plant: 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

Other hypernyms of tape grass include aquatic plant, hydrophyte, hydrophytic plant.

tape grass (noun)	water plant (noun)
submerged aquatic plant with ribbonlike leaves; Old World and Australia	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