47© BOTANICAL GAZETTE [December 



creeping rootstocks to a height of 6 dm. to a meter or more, often 

 forming dense stands over small areas. 



6. Sparganium eurycarpum Engelm. (bur- reed) inhabits water 

 4-6 dm. in depth on the borders of ponds, lakes, and rivers, rising 

 to a height of 8-15 dm. The leaves are linear, mostly flat. While 

 propagation is provided vegetatively by perennial, creeping root- 

 stocks, solid stands of any considerable area are exceptional, 

 growth in small groups being usual. 



7. Typha latifolia L. (common cat- tail) inhabits the marshy 

 banks and shallow water of marshes, lakes, and rivers. The 

 leaves are linear, flat, sheathing at the base, commonly growing 

 to a height of 1-2 m. . The plants usually stand in close clumps 

 and sometimes predominate over a considerable area. Stoma ta 

 are abundant on both sides of the leaves. Propagation is by 

 perennial, creeping rootstocks. 



8. Cast alia odorata (Ait.) Woodville and Wood (sweet-scented 

 water lily) inhabits water of varying depths, covering large areas 

 in shallow ponds and the still water of lakes and slow streams, or 



■ 



mingling freely with open-growing forms of water plants, even 

 occupying the deeper water to the exclusion of other plants when 

 crowded out by competition. The large rootstocks creep through 

 the soft mud, sending up large leaves at the end of long petioles 

 and large, showy, white flowers. The leaves are 0.5-2 dm. wide, 

 orbicular, and float on the surface of the water, frequently partly 

 covering one another in the struggle for space. Stomata occur 

 on the upper side only, but here they are very numerous and their 

 openings are relatively wide. The stomata are kept free from 

 water in the following manner. Kerner (8) states that the leaves 

 - are slightly raised where they join the petiole and the margins are 

 somewhat undulating up and down, so that any water which may 

 find itself thereon will roll down from the center of the leaf to 

 the edge on the slightest rocking movement, where it coalesces 

 with the water on which the leaves float. The under side of the 

 leaves is often colored purple by anthocyanin, by virtue of which 

 the temperature of the leaves is said to be raised somewhat 

 above that of the water, tending to increase the transpiration 

 therefrom. 



