Carex Cyperaceae 265 



Mature perigynia strongly nerved; fertile culms aphyllopodic, strongly reddish- 

 tinged at the base, the lower sheaths filamentose ventrally; ligule at least 



twice as long as wide 121. C. riparia var. lacustris. 



Mature perigynia impressed-nerved; fertile culms phyllopodic, less strongly or 

 not at all reddish-tinged at the base, the lower sheaths not filamentose 

 ventrally; ligule shorter or moderately (less than one and a half times) longer 



than wide 122. C. hyalinolepis. 



Perigynia hairy, the ribs mostly hidden by the short dense pubescence 



122 a. X C. siibimpressa. 



Beaks of perigynia (including teeth) nearly as long as the body; the teeth prominent, 

 1-3 mm long, erect to widely spreading. 

 Perigynia glabrous; leaf sheaths pubescent; at least the lower leaf blades sparsely 



hairy below toward the base 123. C. atherodes. 



Perigynia hairy; leaf sheaths and blades glabrous 124. C. trichocarpa. 



121. Carex riparia Curtis var. lacustris (Willd.) Kiikenth. (Carex 

 lacustris Willd.) Map 549. Common in calcareous soils in marshes and 

 ditches and on borders of swamps, lakes, and streams. It often forms ex- 

 tensive stands in marshes. This, and to a lesser extent the following species, 

 seem to be somewhat periodic in fruiting, at least in the Great Lakes States. 

 Often throughout one or more seasons in a large colony, only a few plants, 

 if any, will be found with fertile culms. 



Que. to Sask., southw. to Va. and Iowa. 



122. Carex hyalinolepis Steud. (Carex riparia var. impressa S. H. 

 Wright and Carex impressa (S. H. Wright) Mack.) Map 550. Common, 

 except in the northern three tiers of counties, in roadside ditches and wet 

 depressions in low open woods and on flood plains and borders of ponds. 



N. J. to Ont. and Nebr., southw. to Fla. and Tex. 



122a. X Carex siibimpressa Clokey. (Rhodora 21: 84. 1919; Carex 

 languinosa X impressa Clokey, Torreya 16: 199. 1916.) Map 551. Known 

 in Indiana from collections by Deam from four counties along the north- 

 eastern border, where it is very local but usually occurs in colonies which 

 are probably clones. It is found in ditches along roadsides or railroads 

 and in low ground in open woods. 



No verifying specimens were found for Clokey's reports from Porter 

 and Posey Counties or for Peattie's report from Lake and Porter Counties. 



Ind. and 111. 



123. Carex atherodes Spreng. (Carex trichocarpa var. imberbis Gray 

 and Carex trichocarpa var. aristata (R. Br.) Bailey.) Map 552. Rare in 

 northern Indiana in marshes and wet prairie habitats. 



Reported from Marshall County by Clark but no specimens could be 

 located. 



Ont. to Yukon, southw. to N. Y., Ind., Mo., Kans., Colo., Utah, and Oreg. ; 

 also in Eurasia. 



124. Carex trichocarpa Muhl. Map 553. Rare in swamps, low openings, 

 and swales in woods ; chiefly in eastern-central Indiana. 



Reported from Madison County by Smith but no specimens were found. 

 Que. and Vt. to Minn., southw. to N. J., Ind., and Iowa. 



