LEMNACE2G. 



781 



surface into the water, and multiplying by similar fronds growing out 

 of their edges. Flowers very rare, appearing from a fissure in the 

 edge of the frond, and consisting of a minute membranous bract or 

 spatlia, enclosing 2 stamens (or 1 only in an exotic species) and a 

 single 1-celled ovary, with one or more ovules, a short style, and no 

 perianth. 



A small genus, widely distributed over Europe, northern Asia, and 

 North America, but rare in the tropics. 



Boots in clusters. Fronds above 3 lines diameter ... 4. Greater D. 

 Roots solitary. 



Fronds very thin, oblong or narrowed at one end (the 

 young ones usually projecting on each side at right 



angles) 1. Ivy-leaved D. 



Fronds broadly ovate, under 3 lines diameter. 



Fronds rather thick, slightly convex underneath . . 2. Lesser D. 

 Fronds very thick and convex underneath 3. Gibbous D. 



1. Ivy-leaved Duckweed. Lemna trisulca, Linn. (Fig. 938.) 

 (Eng. Bot. t. 926.) 



Fronds very differently shaped from 

 those of the other species, and much 

 thinner. They are usually near 6 lines 

 long and about half that breadth, thin, 

 narrow and minutely toothed at one end, 

 and ending in a little stalk at the other, 

 with 2 young ones usually growing from 

 opposite sides near the base, and a single 

 root from underneath. Flowers of the 

 lesser D. 



On ponds and still waters. One of the common species on the Con- 

 tinent, but less so in Britain, especially in the north. Fl. summer, but 

 very rarely. 



Fig. 938. 



2. Lesser Duckweed. Lemna minor, Linn 

 (Eng. Bot. t. 1095.) 



Fronds usually about 2 lines long, 

 broadly ovate or orbicular, cohering 3 

 or 4 together, with 1 root under each 

 but without any stalk, quite entire, and 

 of a rather thick consistence. Ovary 

 with a single ovule. 



On ponds and still waters, throughout 

 the range of the genus, and generally 



(Fig. 939.) 



