FAMILIES OF PLANTS 
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WATER PLANTAIN FAMILY (ALISMACEAE) 
A small family of water plants with scapelike stem and sheathing 
leaves. The Arrowhead (Sagittaria cuneata) grows in shallow water 
and gets its name from the arrowhead-shaped leaves which are all 
basal and form sheaths around the base of the flowering stem. Each 
flower has 3 green sepals, 3 white petals, many stamens and many 
pistils. 
Figure 17. —Arrowhead. White. Photograph hy A. R. Sweetser. 
GRASS FAMILY (POACEAE OR GRAMINEAE) 
This is the most important of all plant families from the standpoint 
of food both for man and for grazing animals. It contains all of the 
cereals, such as wheat, oats, rye, corn, and rice, without which we 
would scarcely know how to live. Grass flowers, however, are wind- 
pollinated and, therefore, they are not conspicuous and are not of any 
great interest to most people. For that reason the family will not be 
treated here in detail. 
The grass that is most frequently asked about by park visitors is 
Giant wild-rye (Elymus condensatus ). This is a large grass usually 
