Utricularia simmonsii is a terrestrial bladderwort endemic to tropical Australia. The species produces the smallest known flowers of the genus, measuring around than 1 mm across. The wine-red blooms are fairly simply in structure, consisting of a small upper corolla lobe that forms a slight hood, and a lower corolla lobe that extends forwards like an extended tongue. The anthers and stamens are presented unobstructed at the middle of the flower. The entire bloom is elevated on a short peduncle around 3 mm tall. The leaves are threadlike and poke out of the substrate.
Utricularia simmonsii is known from the Darwin and Yalayalakamirra Creek regions of the Northern Territory and the Lockhart River region of Queensland. The species is likely more widely distributed but rarely observed due to its cryptic nature. I found the species in the Howard River Sand Plains, growing in a depression likely formed by an old sand extraction operation. A shallow seepage of water flowed over the area, percolating from the surrounding heathland on one side and draining into a wetland on the other side. The plants were growing in a mixture of fine-grained sand and white silt. In the wild the species grows as an annual, dessicating when its environment dries with the onset of the dry season.
The tiny blooms are completely unique within the genus and the species has been assigned to it’s own monotypic section Minutae. The only other species it could be confused with is Utricularia minutissima, whose tiny unopened flower buds can somewhat resemble U. simmonsii and are within a similar size scale. Close examination is enough to distinguish the two species as U. minutissima produces an obvious spur that is absent in U. simmonsii.