3i8 REPORT OF XE\\' JERSEY STATIC MUSEUM. 



l-aniily LEMNACE^. Duckweeds. 



Minute floating aquatic plants, consisting- of a disc-like or 

 globular thallus, often with thread-like roots below. Growth 

 mostly by lateral branching, the branches soon separating and 

 forming new plants. Flowers rare, consisting of either a single 

 stamen or single pistil, appearing on the upper surface of the 

 thallus. The smallest flowering plants known. Apparently 

 absent from the Pine Barrens. 



Key to the Species. 



a. Frond disc-like, 2-8 mm. in diameter. 



b. Rootlets several, diameter of frond 3-8 mm. Spirodcla polyrhica, p. 318 

 bb. Rootlet single. 



c. Frond round oval, diameter 2-5 mm. Lentita iiiinor, p. 318 



cc. Frond pointed at one end, diameter 2-3 mm. 



Lemna perpusilla, p. 318 

 flff. Frond glo])uIar, 7-1.5 mm. in diameter. IVolMa columbiana, p. 319 



SPIRODELA Schleiden. 

 Spirodela polyrhiza (L.). Larger Duckweed. 



Limna polyrhiza Linnaeus, Sp. PI. 970. 1753 [Europe]. — Willis 59. — Britton 



255- 



Floating on the water in ponds, ditches, etc. Frecjuent in the 

 Northern, Middle and Cape May districts. 



Middle District.— Pish House, Delair, Medford (S), Mickleton (H). 

 Cape May. — Green Creek. 



LEMNA L. 

 Lemna minor L. Smaller Duckweed. 



Lemna minor Linnaeus, Sp. PL 970. 1753 [Europe]. — Willis 59. — Britton 254. 



Fref[uent in the same situations as the last and with the same 

 distribution. 



Middle /^/.y^ra-/.— Farmingdalc, Fish House, Delair, Blackwood (S). 

 Cape May. — Cape May. 



Lemna perpusilla Torr. 



Lemna purpusilla Torrey, Fl. N. Y. H. 245. 1843 [Pond on Staten Island]. 

 Willis 59. — Britton 254. 



Similar situations ; reported only from the Northern district 

 and from one locality within oiu^ range, i. e., "Atlantic City — 



