Most species of Lemna, except for L. perpusilla, do not reproduce sexually very often, and the key is based on characters of sterile plants. It is necessary to examine the veins on a mature plant in order to identify the species, but pigments make it hard to see them. Freshly collected plants may be preserved in ethanol, which makes them transparent. If the plant is already dried, it can be boiled in ethanol and then placed in a 10 percent solution of sodium hypochlorite (NaOCl) to remove the pigments. Once the specimens are treated, put them on a microcope slide to permit light to pass through them while viewing.
This Genus’s Species in New England:
Visit this genus in the Dichotomous Key