Bedrock Stream Bottom
Bedrock stream bottom communities are found in stream sections where sedimentary, metamorphic, or igneous bedrock is generally permanently inundated by water. In such riverine communities, vegetation is absent to very sparse. Some aquatic species, like riverweed (Podostemum ceratophyllum) is capable of using holdfasts to attach directly to rock surfaces without the need for roots. Rooted aquatic vascular plants are rare and limited to sand-filled joints or crevices in bedrock (e.g. Sagittaria secundifolia). Otherwise, these communities may support aquatic bryophytes, algae, and cyanobacteria.