[3] Many species are found in a very small geographic area, often even just a single river or waterfall.

[5][6] Riverweeds adhere to hard surfaces (generally rock) in rapids and waterfalls of rivers.

They are submerged when water levels are high, but during the dry season they live a terrestrial existence, flowering at this time.

[7] In many rivers, Podostemaceae are an important food source for a wide range of animals.

For example, the tadpoles of the African goliath frog (world's largest frog) feed only on Dicraeia warmingii,[8] and in South America several serrasalmid fish (Mylesinus, Ossubtus, Tometes and Utiaritichthys) mainly feed on Podostemaceae.