76 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



dried, especially when the plants are stunted by drought. Cattle are 

 particularly susceptible. 



7. ALISMACEAE. Waterplantain family 



Plants herbaceous, aquatic or semiaquatic; stems scapelike; leaves 

 with sheathing bases and usually broad blades; flowers perfect or 

 unisexual; perianth regular, with green calyxlike outer segments and 

 white petallike inner segments; stamens 6 or more; pistils several or 

 many in a ring or a dense head; ovary 1 -celled; ovule usually solitary; 

 fruit achenelike, compressed. 



Key to the genera 



1. Carpels in one or few series; leaf blades not sagittate, short-cuneate to sub- 

 cordate at base; flowers perfect, small, in ample compound panicles. 



1. Alisma. 



1. Carpels in several series, forming a dense head in fruit; leaf blades (some or all 

 of them) commonly sagittate; flowers dioecious, or monoecious with the 

 lower ones pistillate and upper ones staminate, in verticillate simple 



or somewhat compound panicles 2. S agitt aria. 



(Representatives of the genera Echinodorus and Lophotocarpas are also likely 



to be found in Arizona. These differ from Sagittaria, the former in having the 



flowers in ample compound panicles and all perfect, the leaf blades not sagittate; 



the latter in having the lower flowers perfect and the upper ones staminate.) 



1. ALISMA. Waterplantain 



Roots fibrous; leaves mostly emersed with the blades broadly ovate 

 and usually cordate or rounded at base, but the leaves occasionally 

 floating and narrower; inflorescence a large open panicle ; flowers small, 

 perfect; stamens commonly 6; receptacle flat. 



1. Alisma plantago-aquatica L., Sp. PL 342. 1753. 



Near Williams and Mormon Lake (Coconino County), Prescott 

 (Yavapai County), in shallow ponds, 5,000 to 7,000 feet, not common, 

 flowering in summer. Throughout the cooler parts of' the Northern 

 Hemisphere. 



The Arizona form is subsp. brevipes (Greene) Samuelson (A brev- 

 ipes Greene). A pungent volatile oil is obtained from the roots. The 

 leaves are irritating to the skin and have been used medicinally. 



2. SAGITTARIA. 1 * Arrowhead 



Flowering stems from rootstocks, these often tuber-bearing; leaves 

 (in the Arizona species) mostly emersed, with triangular-ovate, deeply 

 sagittate blades; inflorescence a narrow verticillate panicle, simple or 

 branched below ; flowers relatively large, unisexual; stamens commonly 

 numerous; receptacle elevated. 



Plants of shallow stagnant ponds, flowering in summer. One 

 species (S. latifolia) produces edible tubers, eaten by the Indians and 

 Chinese in the Pacific Coast States. The plant is sometimes called 

 "tule potato" in California. 



14 Reference: Smith, Jared G. north American species of sagittaria and lophotocarpus. 1894. 

 Reprinted in Mo. Bot. Gard. Ann. Rpt. 6: 27-64. 1895. 



