■54 MINNESOTA STUDIES IN PLANT SCIENCE 



This plant is very different from the eastern S. pennsylvanica. The 

 unusually small follicles and the rather leathery, yellowish-tinged leaves 

 which are velvety in appearance are the most distinctive characters. In 

 many respects it is very similar to some Rocky Mountain specimens from 

 the United States National Herbarium which Engler and Irmscher (7) 

 have referred to S. montanensis Small. Spanish Basin, Gallatin County, 

 Montana. Rydberg and Bessey No. 4263 (USNH 360877); Bozeman, 

 Montana, Blankinship, No. 521 (MBG 84116). 



Distribution. — Known only from the type locality. 



Specimens examined : 



Minnesota: Winnebago Valley, Houston County, June 12, 1899, W. A. Wheeler, 

 No. 180 (UMH) Type! 



Section Tricarpum, sect. nov. ; 



Micranthes, Small, Fl. S.E.U.S. 501. 1903, as genus; in part. 

 Boraphila, Rosendahl, Beibl. Bot. Jahrb., Nr. 83 :70. 1905 ; in part. 



Receptacle deeply adnate to the ovary ; carpels three, distinct, connected 

 by the receptacle and above by the gland; follicles stout, inflated; styles 

 stout, divergent, rigid; stigmas discoid; gland thick, slightly elevated above 

 the base of the calyx. 



Monotypic, including the species described below. 



The carpels of this section are generally three together, although four 

 are sometimes present. The receptacle attains a considerable depth, enclos- 

 ing the carpels for half their length, in this respect resembling the section 

 Chionophila, and Micranthes in part. The beaks are peculiarly rigid and 

 conical, or somewhat pyramidal, and frequently widely spreading. The 

 stigmas are considerably flattened and sometimes incompletely two-lobed. 

 The gland is not elevated to such an extent as in Micranthes, but as in that 

 section the lower margin persists as a distinct flange around the follicles. 

 The follicles remain connected by the receptacle and the gland, even almost 

 to the base of the styles, but are otherwise distinct to the base, although 

 they appear to be united entirely (Plates II, III, XVIII). 



The single species of which the section is composed is distributed over a 

 rather limited region from southwestern Missouri to the vicinity of Dallas, 

 Texas. Collectors have described it as a plant of sandy or cherty soils. 

 Its range follows the southwestern extension of the Ozark vegetation belt 

 and flanks the Atlantic forest zone, according to Harshberger (15). 



Saxifraga texana Buckl., Proc. Phil. Acad. 1861 :455. 1862. 

 Micranthes texana (Buckl.) Small. Fl. S.E.U.S. 501. 1903. 



Carpels 3, occasionally 4 ; at maturity stout, pyramidal, contracted above 

 into stout conical, spreading beaks. Stigmas small, flattened or discoid. 



