WILD RICE — CHAMBLISS 373 



The female flower is very simple in structure, consisting of lemma 

 and palea that enclose a much-branched stigma and a comparatively 

 small ovary. The lemma bears a long awn or beard. In the male 

 flower, there are also a lemma and palea, which are much shorter than 

 in the female flower. They enclose six bright yellow stamens. 



The seed is long and slender and almost cylindrical (pi. Q, A, D). 

 A thin brown hull made up of the lemma and palea encloses the kernel 

 and bears a long, stiff, straight awn that is covered with numerous 

 barbs or bristly hairs. The surface of the hull itself is covered with 

 similar hairs. 



The kernel of the southern plants averages 20 mm. in length and 

 1.4 mm. in width (pi. 6, E). In the northern plants the kernel has an 

 average length of 12 mm. and a width of 2 mm. (pi. Q, B). There 

 is a shallow groove on the ventral surface of the kernel in which a long 

 embryo is concealed. When fully matured the kernel is purplish black 

 in color. 



Zizania aquatica has two rather distinct forms, and within each 

 there are many variants. The form having broad leaves and long 

 needlelike kernels grows along the tidal rivers emptying into the 

 Atlantic Ocean and is also found locally in the interior as far north as 

 southern Minnesota and Wisconsin. The form with narrow leaves 

 and short thick kernels grows in the upper Mississippi Valley and 

 eastward along the Canadian border. 



In ascending a tidal stream such as the Potomac River, which is 

 salty or brackish almost to the head of tidal water, the halophytic 

 vegetation begins to disappear with the appearance of Scirpus ameri- 

 canus, a fresh-water rush quite resistant to brackish conditions. As 

 the conditions become less saline, fresh-water plants begin to occupy 

 the marshes, and principal among them is Zizania aquatica. If the 

 Zizania marsh slopes gradually into a slow-running stream, several 

 distinct zones of plants will be present. The deeper water will be 

 inhabited by several species of PotaTnogeton^ Vallisneria spiralis, and 

 such free-swimming plants as Lemna and other duckweeds. In 

 water less than 5 feet in depth, the yellow pond lily may occur. 



The next zone is usually narrow and is populated with the pickerel 

 weed {PontedeHa cordata)., which grows in approximately 2 feet of 

 water. Having a very large root system, it is capable of holding its 

 place in a moderate current and serves as a protection to the adjoin- 

 ing zone containing Zizania aquatica., the plants of which are not 

 strongly anchored in the soil. Although such a marsh is inundated, 

 the depth of water covering it varies with the condition of the tides. 



The Zizania zone is broad and usually parallels the stream for 

 some distance (pi. 3). The luxuriant growth of Zizania aquatica 

 shades out most of its competitors, leaving it in possession of the 



