88 Karl M. Wiegand and Arthur J. Eames 



N. H. to Wyo., southw. to Fla. and Ariz., including the Coastal Plain. Found also 

 in Mex. and Cent. Am. 



The var. spissum Linder (see Rhodora 24: 15. 1922) is not well defined in this 

 flora. 



8. P. depauperatum Muhl. 



Dry sandy slopes and thickets, in the more acid soils ; rare. June. 



Junius, borders of woods e. of the peat bogs. 



Me. to Minn., southw. to Ga. and Tex. ; common on the Coastal Plain. 



9. P. linearifolium Scribn. 



Dry gravelly slopes and thickets, in sterile, somewhat acid, chestnut soils ; 

 frequent. June-July. 



Not uncommon on the hills s. w., s., and s. e. of Ithaca, on the crests of the ravines, 

 in the gravelly and stony soils along the shore of Cayuga Lake, and at Junius. 



Me. to Kans., southw. to Ga. and Tex. ; infrequent on the Coastal Plain. 



9a. P. linearifolium Scribn., var. Werneri (Scribn.) Fernald. (See Rhodora 23:194. 

 1921. P. Werneri Scribn.) 



In situations similar to the preceding, and with the same distribution, often grow- 

 ing with it; frequent. June. 



N. S. to Minn., southw. to Ohio and Tex. ; occasional on the northern Coastal Plain. 



None of the characters mentioned by Scribner (Rhodora 3: 118. 1901) as separat- 

 ing P. Werneri from P. linearifolium are constant in this region except the glabrous 

 culms and foliage. Material at hand, of the two forms, is identical except for the 

 difference in pubescence. In this character there is very little transition; yet, this 

 being the only difference, it would seem better to treat the plant as a variety of 

 P. linearifolium. 



10. P. dichotomum L. (P. d., var. nitidum and var. viride, of Cayuga Fl.) 



Dry gravelly or sandy open hillsides and banks, and in open woods, mostly in 

 acid chestnut soils ; common. June 20-July. 



On the chestnut soils of the hills w., s., and s. e. of Ithaca, on the ravine crests and 

 the crests of the cliffs along Cayuga Lake, and in the sandy soil n. of the lake; rare 

 or absent in the McLean district and on the clays and richer soils back from the 

 lake shores. 



N. B. to Mich., southw. to Fla. and Tex., including the Coastal Plain. 



Plants in exposed situations often have firm leaves up to 9 mm. wide, whereas 

 the shade forms have very narrow, more widely spreading, leaves. 



11. P. Lindheimeri Nash, var. septentrionale Fernald. (See Rhodora 23: 223. 1921.) 

 Dry or damp sandy or gravelly fields and banks, often apparently in calcareous 



soils ; frequent. June 20-Aug. 10. 



Coy Glen ; near Forest Home ; w. of East Lansing ; Taughannock Gorge and Point ; 

 ravine s. of Genoa; gravel along shore s. of Union Springs. 



N. S. to Man., southw. to Conn., N. Y., Ind., and Mo. ; apparently rare on the 

 Coastal Plain. 



Three forms occur: (a) with leaves glabrous both above and beneath; (b) with 

 leaves glabrous above but hairy beneath; and (c) with leaves hairy on both faces. 

 This variety forms the greater part of the P. tennesseense of Gray's Man., ed. 7, and 

 is part of the P. dichotomum of the Cayuga Flora. Several forms of this species 

 have been treated as species but they are certainly not distinct. The treatment by 

 Fernald is here followed, though it is not clear that the primary division should be 

 made on the pubescence of the inflorescence rather than on that of the leaves. In 

 the local specimens the glabrous or hairy upper and under surfaces of the leaves 

 are fairly clear-cut characters showing almost no transition. 



