Peter Taylor lists it as either an "aquatic-epiphyte", a subaquatic or a terrestrial species.

U. humboldtii is endemic to South America, where it is found in Brazil, Guyana, and Venezuela.

It is usually found growing in the water-filled leaf axils of some species of bromeliad, including Brocchinia micrantha, B. tatei, and B. reducta and also plants in the genus Orectanthe.

It also grows as an epiphyte on tree trunks or as a subaquatic or terrestrial species in shallow water or wet soil in open savanna.

As it usually lives within the water-filled leaf axils of bromeliads, it occasionally needs to search for new pools of water, so it sends out upright stolons that find nearby bromeliads, descend into the water, and grow into a new plant.