This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Thallus thin, unsymmetrical, rootless, curved in the form of a segment of a band, punctate on both surfaces with numerous brown pigment-cells. Pouch opening as a cleft in the basal margin of the thallus, a stipe attached to its margins. Flowers and fruit unknown. [Diminutive of Wolffia.]
1880. Wolffia floridana J. D. Smith; Hegelm. Engler's Bot. Jahrb. 21:
Wolffiella floridana Thompson, Ann. Rep. Mo. Bot. Card. 9: 17-
Thalli solitary, or commonly coherent for several generations forming densely interwoven masses, strap-shaped, scythe-shaped, or doubly curved, tapering from the rounded oblique base to a long-attenuate apex, 21/2"-5" long, 14-21 times as long as wide; basal portion of the long stipe persistent, the pouch elongated-triangular, or the upper angle rounded.
Georgia and Florida to Missouri, Arkansas and Texas.