348 LEMNAGEA AND TYPHACEJE. 



Order 112. LEMNACEffi — Duckweed Family. 



Minute stemless plants, floating free, on the water, destitute of distinct stem and 

 foliage, but a flat frond, producing one or two monoecious flowers from a chink at 

 the edge or upper surface, and usually hanging roots from underneath. Fructifica- 

 tion much as in Araceae, of whicn these plants appear to be minute and gxeatW 

 reduced forms. 



LEMNA, Linn. Duckweed. 



The Greek name of uncertain meaning, 



Flowers 2 to 3, appearing from the margin cf a flat 

 frond, enclosed in a spathe, monoecious : the sterile consist- 

 ing of 1 to 2 stamens with long filaments; the fertile of a 

 1-cclled ovary, a short style and a simple stigma. Fruit a 

 utricle. — Floating annuals, consisting of a stem and leaf 

 confounded (frond) sending down from the under surface, 

 roots which hang loosely in the water, and producing the 

 spathaceous flowers from the margins, which are seldom found. 



1. L. MINOR, L. Lesser Duckweed. 



Fronds roundish-obovate, thiekisk, often grouped; root solitary ; ovule solitary.; 

 teed horizontal. 



Stagnant water, very common ; but not yet found in flower in this country. 

 Fronds X / A inch long, somewhat fleshy, increasing rapidly by gemma (young fronds') 

 so as often conipletely^te-eover the surface cf the water. 



2. L. trisulca, L. Star Duckweed. 



Fronds oblong-lanceolate, from a stalked base, thin, denticulate at the tip, pro- 

 liferous from the sides near the middle so as to form crosses; flowers very minute; 

 ovule solitary, half anatropous. 



Ditches and ponds ; rarely in flower. Fronds % inch or mere long . 



3. L. polyriiiza, L. Larger Duckweed. 



Fronds roundish-ovate, thickish, flat above, palmately veined, (J4 to \£ mc h long 1 ) 

 often dark purple beneath; rcot a bundle of 8 to 10 simple fibres in the middle of 

 the frond. 



Stagnant waters, rare. It is. said never to have been seen in flower in thi« 

 country. 



Order 113. TYPHACEJE.— Cat-tail Family. 



Marsh herbs, with nerved and linear sessile leaves, and monoecious flowers on a spa* 

 ■dix or in heads, destitute of proper floral envelopes. Ovary tapering into a slender 

 style, and usually an elongated tongue-shaped 1-sided stigma. Fruit nut-like when 

 ripe, 1-secded. Ssed suspended, anatropous. 



1. TYPHA, Tourn. Cat-tail Flag. 



Gr. typhos, a marsh; alluding to the plase of its growth. 



Flowers in long and very dense cylindrical spikes, termi- 



