Coefficient of Conservatism:
Coefficient of Wetness:
B. S. Slaughter
A circumpolar and usually calciphile species, its range extending in some places, like that of U. intermedia and U. vulgaris, north of the Arctic Circle. Fens (sometimes in sphagnum), sedge mats, swales and marshes; wet open thickets and peaty lake margins; often in ruts and animal trails in such habitats.
In shape, the leaves resemble very miniature flat fronds of staghorn fern. This species and U. gibba are both very slender and small-flowered, the corolla not over 9 mm long, and they often grow intermixed. The more flattened leaf segments of U. minor are nearly always easily seen under a lens. Small shoots (e.g., from turions) of U. intermedia may resemble U. minor but can be distinguished by the complete absence of bladders and the presence of marginal spicules on the leaf segments. The flowers of U. minor, being a rather pale dirty yellow, are not as conspicuous as the equally small but bright yellow ones of U. gibba and U. geminiscapa, apart from the more chubby and less linear shape of these two. Some fragmentary specimens that otherwise appear to be U. minor have unusually narrow, elongate, flat ultimate leaf segments with a few marginal spicules; they may be derived from expanded turions.