ALJSMACE^J. 



793 



faint longitudinal nerves at some distance 

 from it. Peduncles usually bearing se- 

 veral clusters of 2 or 3 flowers, at some 

 distance from each other, forming a 

 slender interrupted spike, rarely reduced 

 to a single small terminal cluster. Nut 

 as in the slender P. 



In pools, ditches, and still waters, 

 fresh or salt, almost all over the world. 

 Generally distributed over Britain. FL 



Fig. 955. 



LXXVIII. THE ALISMA FAMILY. ALISMACE^E. 



Marsh or water plants, with radical leaves and leafless flower- 

 stems (except in Scheuchzeria) . 3?lower3 in terminal umbels, 

 panicles, or racemes. Perianth of 6 segments, either all similar, 

 or 3 outer small and sepal-like, and 3 inner ones larger and petal- 

 like. Stamens 6, 9, or indefinite. Ovary of 3, 6, or many carpels, 

 either distinct from the first or separable when in ripe fruit, each 

 with 1, 2, or many ovules. Seeds consisting, within the testa, of 

 a homogeneous mass, usually considered as an undivided em- 

 bryo without albumen. 



The genera are not numerous, but several of them dispersed over the 

 greater part of the world. 



Perianth-segments all nearly equal, large and coloured. 



Flower-stem tall, with a large terminal umbel ... 1. Butome. 

 Perianth-segments 3 small and herbaceous, 3 large and 

 coloured. Flowers opposite or whorled, in a termi- 

 nal raceme, umbel, or panicle. 

 Carpels and stamens numerous. Leaves sagittate . . 2. Akkowhead. 

 Carpels numerous. Stamens 6. Leaves ovate or narrow 3. Alisma. 

 Carpels 6. Stamens 6. Leaves ovate or oblong . . 4. Damasonium. 

 TOL. II. Z 



