The Flora of the Cayuga Lake Basin 55 



1. Elodea Michx. 



a. 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 stipe-like 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. E. canadensis 



a. 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. E. occidentalis 



1. E. canadensis Michx. (Including E. Planchonii Caspary and E. ioensis Wylie.) 



Water-weed. 



Pools and slow-flowing streams, in more or less calcareous waters ; common, 

 especially near Cayuga Lake and on the Ontario plain. July-Aug. 



Que. and N. E. to Sask. and Wyo., southw. to N. Y., Ky., and 111. ; rare on the 

 Coastal Plain. 



Recent authors (see St. John, Rhodora 22: 17. 1920) have treated E. canadensis 

 and E. Planchonii as distinct species. After an extended study of the local material 

 and that in one of the larger herbaria, the view is taken that they represent the two 

 sexes of the same species. 



2. E. occidentalis (Pursh) St. John. Water- weed. 



In locations similar to the preceding ; more local. July-Aug. 



Reported only from near the mouth of Fall Creek, but probably occurring else- 

 where about Cayuga Lake. 



S. Me. to Wis. and Oreg., southw. to D. C, Mo., and Nebr. More frequent 

 than the last-named species in the more sandy noncalcareous and brackish regions. 



2. Vallisneria (Michx.) L. 



1. V. americana Michx. (See Rhodora 20: 108. 1918. V. spiralis of Cayuga Fl.) 

 Eel Grass. 

 Lakes and larger slow-flowing streams ; locally common. Aug. 

 Cent. Me. to S. Dak., southw. to Fla. and Tex. ; occasional on the Coastal Plain. 



18. GRAMINEAE (Grass Family)* 



a. Spikelets 1-many-flowered, terete or laterally compressed, when 2-flowered the 

 lower floret not sterile and not of a different texture from the upper floret; 

 internodes usually present between the flowers ; rhachilla generally articulated 

 above the empty glumes (several exceptions). 



* The terms empty glumes, flowering glumes, and palets have been retained here, because 

 they are of particular pedagogical value in indicating homology in the grass spikelet. According 

 to this terminology, all leaf organs on the primary axis are glumes, and those on the secondary 

 axis arei palets. The two regularly empty glumes are termed empty glumes; if others above are 

 staminate or neutral, they are termed sterile flowering glumes, a designation which expresses their 

 real nature. Palet is a more distinctive term than palea, as the latter term is used in other 

 families and often without morphological significance. 



The tribes are here presented in an order almost inverse to the usual sequence, because this 

 seems to represent more nearly the probable course of evolution. The earlier tribes are less 

 specialized, the later ones more so. The Festuceae are probably the most primitive, with the 

 Hordeae branching off in one direction, and the other tribes forming a series which branches 

 off in another directiqn. The arrangement is essentially the same as that in Hitchcock's 

 Genera of Grasses of the United States (United States Department of Agriculture, Bui. 772). 



Measurements giving the length of empty or of flowering glumes are exclusive of the awns. 



