THE MISSOURI SAXIFRAGES. 



BY B. F. BUSH. 



The genus Micranthes of eastern North America, which 

 has generally been referred to the genus Saxifraga, is repre- 

 sented by some twenty species, mostly plants of alpine 

 heights and mountainous regions, and therefore not likely to 

 be found in the low altitude of the States of the Mississippi 

 Valley, only the two lowland species reaching our northeast- 

 ern borders. A species of the Southwest, but little l^nown, 

 native of sandy woods and bottoms and rocky barrens, has 

 been ascertained to reach our southwestern borders, where 

 it is native of the cherty rocky barrens. Through the 

 kindness of Professor Trelease, I have been permitted to 

 examine all of the Missouri material of this genus, and also 

 some specimens from elsewhere, and after a careful study of 

 this material, I make for the Missouri species the following 

 arrangement : 



Acaulescent, the principal leaves in a basal rosette; scapes naked be- 

 low the inflorescence, minutely bracted above. 

 Sepals reflexed; plants large, 3-10 dm. tall; leaves denticulate or 

 entire. Micranthes pennsylvanica. 



Sepals erect ; plants low, 5-45 cm. tall ; leaves dentate. 



Petals oblong, twice or thrice as long as wide, much longer tlian 

 the sepals; pedicels slender, glandular-pubescent. 



Micranthes virginiensis. 

 Petals obovate, one to one and one-half times as long as wide, a 

 little longer than the sepals; pedicels stout, glabrous. 



Micranthes texana. 



Micranthes pennsylvanica (L.) Haw. Saxifr. Enum. 45. 

 1821. 



Saxifraga pennsylvanica L. Sp. PI. 399. 1753. 



Saxifraga Forbesii Vasey, Am. Entom. & Bot. 2 : 288. 1870, based on 

 specimens collected by Forbes at Makanda, Illinois, is said to differ 

 in having thinner leaves, which are pilose beneath, and to it all 

 the Missouri specimens have been referred. I have been unable 

 to separate this from M. pennsylvanica, as I find the thickness of 

 the leaves and pubescence very variable. If, however, the species 

 must be maintained, Saxifraga Forbesii Vasey, should be written 

 Micranthes Forbesii (Vasey) new comb. 



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