Lemnaceae, the Duckweed Family
Minute leafless plants floating on quiet water; flowers exceedingly small and seldom seen.
| 1a. Plant thick, ovoid, less than 2 mm. long; roots none. Two species are reported from Michigan | Wolffia spp. |
| 1b. Plant flattened, with short roots — 2. | |
| 2a. Roots several from each rounded plant | Duckweed, Spirodela polyrhiza. |
| 2b. Root single from each rounded plant | Duckweed, Lemna spp. |
| Three species are reported from Michigan, of which the commonest is Lemna minor. |