Utricularia minutissima Species Profile

Utricularia minutissima Species Profile

Utricularia minutissima is a species of terrestrial bladderwort found in tropical regions of Australia and SE Asia. As its name suggests, the species can be tiny. This post describes the diminutive Darwin form, which might possibly be distinct from the larger form found across SE Asia.

There is considerable size differences in the species, with the plants I saw around Darwin producing flowers around 2 mm in length. Other populations are known to be much larger (relatively speaking). The species produces pink to purple blooms, The lower corolla lip is domed, and shallowly divided into three lobes at its extremity. The spur is longer than the lower corolla lip and thrust forwards at a horizontal axis, typically curving upwards at the end. The upper corolla lip is small. The peduncle is glabrous.

I observed U. minutissima growing in wet sandy substrates in seepages within the seasonally inundated floodplains near Darwin. The species was common although its diminuitive size meant that it was often overlooked. Although many flower buds were seen, the open flowers were rare (perhaps due to bad luck).

U. minutissima is recognisable by its domed flowers. The small form I observed can be distinguished from other domed species by its size alone, but unopened flower buds could be mistaken at a glance for U. simmonsii, which occurs at a similar size scale. Careful examination is enough to distinguish it. Larger forms are known to be confused U. geoffrayi which has almost identical blooms. U. minutissima can be distinguished by its glabrous peduncle (that of U. geoffrayi has sparse hispid indumenta) and plain palate (that of U. geoffrayi has two yellow dots on it).

Note the domed lower corolla lip, long spur and plain palate
A semi opened bloom
An unopened bud along with a misformed flower
A small grouping of plants growing in sand
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