Azolla pinnata

Azolla pinnata R. Br.
(Latin: pinnatus, feathered, winged, plumed, in reference to the pinnately arranged branches)

Local names: feathered mosquito fern, water velvet

This is a widespread Old World native that is listed as a U.S. federal noxious weed (USDA Natural Resources Conservation Service 2010), and as such is prohibited in the U.S. by federal law. There is concern it could be invasive. Yatskievych and Windham (2008a) noted that it “appears sporadically as a contaminant in commercially grown aquatic plants imported from other regions.” This species, currently unknown from TX, can be distinguished from all TX species by its 9 megaspore floats (vs. 3 in all TX species). It also has pubescent stems with obviously pinnately arranged branches, the longer basal ones giving the pant a decidedly triangular appearance (vs. glabrous stems at least somewhat dichotomously branched and the plant much less triangular in all TX species). Given the large number of other invasive exotic aquatics that have been introduced into TX, this specie sis included here as a note to alert collectors and others to be aware of it as a possibility. In southeastern Asia it has been used for centuries as a natural fertilizer in the cultivation of rice (Lumpkin 1993).

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