Aquatic and Wetland Vascular Plants of the Northern Great Plains

6. Salviniaceae, the Water Fern Family

1. Azolla Lam. -- Mosquito fern

1. Azolla mexicana Presl

Small, annual, free-floating plants up to 3 cm across, often forming mats, sometimes stranded on mud; plant body comprised of dichotomously branched stems clothed with tiny, alternate, overlapping leaves in 2 rows, green or often strongly red; roots few, unbranched. Leaves 2-lobed, the upper lobe emersed, rhombic-ovate to obovate, 0.7-1.3 mm long, the lower lobe submersed and larger than the upper, mostly achlorophyllous. Sporangia heterosporous, the micro- and megasporangia contained in separate sporocarps which are usually paired on the submersed lobes of some of the leaves. Jul--Oct. Quiet water of marshes, ponds, streams and ditches; scattered in NE; (WI to NE and B.C., s to TX, CA and into Mex. and S.Amer.).


Azolla mexicana, greatly enlarged.

Return to Family -- Salviniaceae - The Water Fern Family