92 



Hydrocharitaceae 



Vallisneria 



o 5o 



Map 116 



Anacharis canadensis (Michx.) Planch. 



~5o 



Map 117 



Anacharis occidentalis (Pursh) Vict. 



^3 

 Map 118 



Vallisneria americana Michx. 



1. Anacharis canadensis (Michx.) Planch. (Eiodea of Gray, Man., ed. 7 

 and Philotria of Britton and Brown, Illus. Flora, ed. 2.) Canada Water- 

 weed. Map 116. Frequent to common in most of our lakes, ponds, slow 

 flowing streams, and ditches of the lake area, becoming rare southward 

 because its habitat is not found. It prefers clear and calcareous waters. 

 Wiegand, in his study of the species, concludes that Anacharis canadensis 

 is dioecious and that Anacharis Planchonii is the pistillate form of the 

 species. 



Que., N. E. to Sask. and Wyo., southw. to N. Y., Ky., and 111. 



2. Anacharis occidentalis (Pursh) Vict. (Contrib. Lab. Bot. Univ. 

 Montreal 18: 50: 1931.) {Philotria angustifolia of Britton and Brown, 

 Illus. Flora, ed. 2 and Eiodea Nuttallii (Planch.) St. John.) Western 

 Waterweed. Map 117. This species has the habitat of the preceding 

 species but is less frequent. Most of our specimens are from the lake 

 area. 



Southern Maine to Wis. and Oreg., southw. to D. C, Mo., and Nebr. 



89. VALLISNERIA [Micheli] L. 



1. Vallisneria americana Michx. (Rhodora 20: 108. 1918.) {Vallisneria 

 spiralis of Gray, Man., ed. 7 and Britton and Brown, Illus. Flora, ed. 2.) 

 Wild Celery. Map 118. Infrequent to frequent or even common in the 

 lakes of the lake area and rare in our streams, except those of the lake area 

 where it may be common. The sepals of my specimens and those which I 

 have measured in the field are rounded at the apex and 3-3.5 mm wide 

 and 3-5 mm long, usually slightly less than 4 mm long. The peduncles 

 of the staminate inflorescences are mostly about 1 cm long and the leaves 

 are 6-8 mm wide. The widest leaf I have been able to find was 9 mm wide. 



Cent. Maine to S. Dak., southw. to Fla. and Tex. 



97. LIMNOBIUM Richard 

 See excluded species no. 38, p. 1024. 



