372 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1940 



men and for nearly 200 years had supplied the food wants of many 

 European adventurers. 



This grass, indigenous to North America, is found from Lake Win- 

 nipeg to the Gulf of Mexico and eastward from the Rocky Moun- 

 tains to the Atlantic coast. Throughout these latitudes, and in 

 this area where conditions are favorable, it is conspicuous among the 

 aquatic plants growing in shallow lakes and in slow-moving streams. 

 In the extreme northern and eastern limits of this region it often 

 covers several hundred acres. Within its natural range the species 

 often occupies the small bays of the large lakes, covers the mud flats 

 on tidal rivers of the Atlantic Coastal Plain, fills the lakelike ex- 

 pansions of rivers near their source, and grows luxuriantly in the quiet 

 bends of sluggish streams. It is seldom found in the inland lakes with 

 no outlets. It grows well on a variety of soils under fresh-water 

 streams and lakes. Its best growth, however, is made wherever the 

 plants can anchor themselves in a thick layer of mud, regardless of 

 the kind of soil. 



Zizania aquatica is an aquatic, annual, self -sowing grass having tall, 

 erect, cylindrical, and hollow stems, which bear the inflorescence and 

 four to six long leaves with flat blades, conspicuously marked by a 

 very thick midrib (pi. 4). The slender stems have a comparatively 

 thin wall, and when seen by transmitted light, they show thm, trans- 

 verse partitions, dividing the internodal space into compartments, 

 which gives the stems a light banded appearance. 



The stems vary in height from 5 to 10 feet and in diameter from 

 one-fourth to five-eighths of an inch. The taller plants are char- 

 acteristic of the tidal flats and the shorter plants of the northern 

 lakes and streams. Plants with stalks as thick as 2 inches near the 

 crown are not unusual in southern marshes. In thin stands and 

 among isolated plants a single plant may have many stems, some aris- 

 ing from the base of the mother stem, though frequently as branches 

 from the first and second nodes. 



The principal roots are slender, fibrous, and numerous and do not 

 penetrate deeply into the soil. 



The first leaves to appear are long and narrow. In the later and 

 permanent leaves the basal part known as the sheath is thick and 

 spongy in structure and completely wraps the stem, thereby adding 

 much to its rigidity. The sheaths vary in length from 9 to 25 inches. 



The blade is the free end of the leaf. In the terminal leaves it may 

 be 2 to 4 feet long and from less than an inch to 1 inch or more wide. 



The inflorescence (pi. 5) is borne on the last node of the stem. 

 It consists of two parts — an upper, with slender straight branches 

 bearing the female or seed-producing flowers, and a lower, with 

 drooping branches bearing the male flowers. 



