Which type of aquatic plants can have their vegetative tissue all or mostly below the water surface?

Submersed plants are characterized by having their vegetative tissues primarily or entirely below the water surface. This adaptation allows them to thrive in aquatic environments, as they are fully submerged, with leaves and stems often floating or growing underwater. These plants play a crucial role in aquatic ecosystems by providing habitat and food for various aquatic organisms, contributing to overall biodiversity.

In contrast, floating plants are those that have most of their vegetative tissue above water, allowing them to float on the surface. Emersed plants typically grow with their roots in the water but have majority of their stems and leaves above the surface. Vascular plants is a broader category that includes all types of plants with vascular tissues, such as trees, shrubs, and flowers, and does not specifically denote the location of their vegetative tissues in relation to water. Thus, submersed plants are the correct choice, as their defining feature is being mostly under water.