Hydrolea uniflora, commonly known as the oneflower false fiddleleaf, is a species of flowering plant in the family Hydroleaceae. It is endemic to the central and southeastern United States, where it occurs primarily in wetland habitats.
Description Hydrolea uniflora is a subshrub characterized by axillary cymes and typically glabrous to minutely puberulent stems and calyces. Leaves are variable in size depending on environmental conditions, with submersed leaves often much smaller than emersed leaves. The species produces blue to violet flowers typical of the genus Hydrolea.
Distribution and habitat Hydrolea uniflora is endemic to the central and eastern-central United States, including Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, Oklahoma, Tennessee, and Texas. Its distribution is centered in the Mississippi River Alluvial Plain, extending west to eastern Texas and east to Alabama, Tennessee, and Kentucky. It inhabits wetland environments such as swamp forests, sloughs, marshes, and other low-lying moist areas. Occurrence records indicate that the species is well documented across its range, with over 1,200 recorded observations in biodiversity databases.
Ecology Hydrolea uniflora is an obligate wetland species (OBL), meaning it almost always occurs in wetlands under natural conditions. It is adapted to hydric environments and exhibits morphological plasticity in response to water conditions, particularly in differences between submerged and emergent leaf forms.
Phenology Flowering occurs from June through September.
Conservation status Hydrolea uniflora is ranked as G5 (secure) globally by NatureServe, indicating that it is widespread and not at risk of extinction across its range. Despite its global security, the species is considered rare in parts of its range. It is ranked as S1 (critically imperiled) in Kentucky and S2 (imperiled) in Illinois, while remaining unranked or not assessed (SNR) in most other states. The species depends on wetland habitats, which may be impacted by drainage, land conversion, and hydrological alteration.
Taxonomy The species was first described by C. S. Rafinesque in 1840. The holotype specimen of Hydrolea uniflora was collected in the United States and is preserved at the Louisiana State University Herbarium. Synonyms include Hydrolea affinis, Hydrolea leptocaulis, and Nama affinis.
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