Anacharis Hydrocharitaceae 91 



our most common species. This arrowhead is more robust than Sagittaria 

 latifolia with which it is sometimes associated. It is found on the muddy 

 shores of streams, ponds, and sloughs and in ditches. I have seen speci- 

 mens from Iowa, Illinois, Wisconsin, Missouri, and Tennessee. 



4. Sagittaria australis (J. G. Smith) Small. Map 113. This is a south- 

 ern species which is known only from Perry County. It is found on muddy 

 shores. 



Pa., Va., and Ind. to Ala. 



5. Sagittaria rigida Pursh. (Sagittaria heterophylla Pursh.) STIFF 

 Arrowhead. Map 114. This species is essentially northern in its distribu- 

 tion and is practically restricted to our lake area with a few locations 

 south of it. It is infrequent and found on muddy borders and in ditches. 

 The leaves are extremely variable, ranging from linear to rather broadly 

 elliptic. Three forms have been named, but I believe these ecological 

 fluctuations do not merit names. 



Que. to Minn., southw. to N. J., Tenn., and Kans. 



6. Sagittaria graminea Michx. Map 115. Infrequent in a part of the 

 lake area and local southward. This species is usually found in shallow 

 water or in very wet places about lakes, ponds, and artificial ponds and 

 in ditches. 



Newf. to Sask., southw. to Fla. and Tex. 



17. HYDROCHARITACEAE Asch. Frogbit Family 



Leaves less than 2 cm wide. 



Plants with long, leafy submerged stems ; spathes very small, sessile 



87A. Anacharis, p. 91 



Plants stemless, submerged, with long narrow leaves ; spathes peduncled 



89. Vallisneria, p. 92. 



Leaves more than 2 cm wide 97. Limnobium, p. 92. 



87A. ANACHARIS Bab. & Planch. Waterweed 



[Victorin. L' Anacharis canadensis. Contrib. Lab. Bot. Univ. Montreal 

 18: 1-43. figs. 7. 1931.] 



K. M. Wiegand has made an extensive study of the species of this genus 

 in the Cayuga Lake Basin and has published his findings in the "Flora of 

 the Cayuga Lake Basin," by Wiegand & Eames. I have taken the following 

 key from this work, and I here make acknowledgment for its use. 

 Leaves 1.2-4 mm wide (averaging 2.13 mm) ; spathe of the staminate flower oblong- 

 linear, 11-13 mm long, constricted at base into a stipelike part, the orifice gaping, 

 2-lobed ; staminate flower remaining attached by means of a long filiform peduncle ; 

 sepals or mature bud of the staminate flowers 3.8-5 mm long; anthers 2.2-2.5 mm 



long; sepals or mature bud of the pistillate flowers 2.3-2.7 mm long 



1. A. canadensis. 



Leaves 0.7-1.8 mm wide (averaging 1.3 mm) ; spathe of the staminate flower globose, 

 apiculate, the body about 2 mm long; staminate flower sessile, breaking out of the 

 spathe and rising free to the surface before anthesis; sepals or mature bud of 

 the staminate flowers 2-2.5 mm long; anthers 0.8-1.1 mm long; sepals or mature 

 bud of the pistillate flowers 1.2-1.8 mm long 2. A. occidentalis. 



