Sea grass and Water plant

Water plant and sea grass are semantically related in algae topic. In some cases you can use "Water plant" instead a noun "Sea grass", when it comes to topics like kelp.

Water plant 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.

Sea grass and water plant are semantically related in algae topic. You can use "Sea grass" instead a noun phrase "Water plant", if it concerns topics such as kelp.