222 



Cyperaceae 



Carex 



50 



Map 426 



Carex mesochorea Mack. 



50 



Map 427 



Carex Muhlenbergii Schkuhr 



Map 428 

 Carex Muhlenbergii 

 var. enervis Boott 



9. Carex mesochorea Mack. (Bull. Torrey Bot. Club 37: 246. 1910.) 

 (Carex mediterranean Mack.) Map 426. Rare or local in pasture fields and 

 on open, wooded, grassy slopes. At the Montgomery County station, on an 

 open white oak ridge 5 miles west of New Market, it is associated with 

 Poa pratensis, Danthonia spicata, Luzula echinata var. mesochorea, Anten- 

 naria neglecta and "reindeer moss." 



Southern Mass. and N. Y., to D. C, Tenn., and Ind. 



10. Carex Muhlenbergii Schkuhr. Map 427. Frequent to common in 

 the lake area in dry sandy fallow fields and open oak woods and on dunes ; 

 occasional in southern Indiana. 



Maine to Minn., southw. to Fla. and Tex. 



10a. Carex Muhlenbergii var. enervis Boott. (Carex plana Mack. Bull. 

 Torrey Bot. Club 50: 350. 1923.) Map 428. Frequent on slopes, in sandy 

 open woods, on wooded dunes, and in dry sandy fields. It is partial to 

 somewhat less open habitats than the species and is less often on low or 

 level ground, its favorite habitat being on or near the crests of wooded 

 dunes, river bluffs, and oak ridges. 



Specimens intermediate between C. Muhlenbergii and var. enervis in 

 some or most of their characters seem to be too frequent to warrant the 

 treatment of the latter as a species. The ventrally flat perigynium is a 

 conspicuous character of typical var. enervis when fully mature or over- 

 ripe but it is very inconstant and specimens with a pronounced raised 

 border up to maturity are especially frequent. 



Maine to Nebr., southw. to Ala. and Tex. 



11. Carex gravida Bailey. (Including Carex gravida var. laxifolia 

 Bailey.) Map 429. Known in Indiana only from the prairie area in the 

 westernmost tier of counties where it is found on sandy bur oak ridges 

 and sandy and gravelly railroad embankments. 



