Wolffia columbiana H. Karsten, . Wolffia columbiana — COLUMBIA WOLFFIA, COMMON WATER–MEAL Short–lived aquatic herb, clonal via fragmentation forming dense, floating colonies, lacking roots, not rosetted, unit = a mother frond and mostly with daughter frond in line (alternate distichous) arising from basal pouch, the daughter frond breaking free to become new mother frond; frond = minute stem (basal portion) + leaf, highly modified, terminal pouch defined by circular rim and containing a deep–seated shoot tip to produce a daughter frond (exceedingly rarely an inflorescence), buoyant at water surface but mostly submersed, surface wettable, glabrous.
Stem (stipe) connecting daughter frond from pouch at base of mother frond, inconspicuous.
Frond scarcely above water, at maturity spheric to subspheroid, in range as individual frond 0.35—1 × 0.35—0.9 mm, green senescing colorless, rounded at tip, after daughter frond released initially depressed at that end with narrow rim, exposed surface minutely textured (epidermal cell outlines), lacking papillae or central point.
Inflorescence not observed in range.
A. C. Gibson