6 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



MARSILIACEAE. 



Marsilia vestita Hook. & Grev. Ic. Fil. fl. ijg [Man. R. M. 437 ; 



Our Native Ferns, 126; 111. Fl. i : 34 ; Bot. Cal. 2: 351]. 



In shallow water, rare, reaching an altitude of 2000 m. 



Montana: Upper Missouri, Gcvcr : Lower Sand Coulee, 1891, 

 R. S. WiUiams, 857: Big Blackfoot, 1880, Watson. 



Yellowstone Park : Coulter. 



EQUISETACEAE. 

 Equisetum arvense L. Sp. PL 1061 [Man. R. M. 445 : Our Native 



Ferns, 133; 111. Fl. i : 36 ; Bot. Cal. 2: 330], 



In damp places, especially in sand}' soil, to an altitude of 2000 m. 



Montana: Lewis & Clarke Co., Mrs. Math; Upper Sand 

 Coulee, 1888, R. S. Williams, 8ij; Grizzly Creek, 1887, Tzcecdy, 

 i6g. 



Yellowstone Park: Swan Lake, 1885, Tzcccdy, Soi ; Yellow- 

 stone Lake, Adams. 



* Equisetum arvense campestre (Schultz) Milde, Filices, 217; R. 



campestre Schultz, Fl. Starg, Suppl. I : 59 ; R. arvense var. sero- 



tinmn, Meyer, Chlor. Han. 1836. 



It differs from the type in the fact that it bears small spikes on the 

 low and slender sterile shoots. It grows in muddy places up to an 

 altitude of 2000 m. 



Montana: Cedar Mountain, July 16, 1897, Rvdberg d- Bessey. 



* Equisetum fluviatile L. Sp. PL 1062 [111. Fl. i : 37] ; R. limosum 



L. Sp. PL 1062 [Our Native Ferns, 134]. 



Stems annual, all alike, with short branches and appressed sheets. 

 It is a rare plant, growing in water. 



Montana: Columbia Falls, 1892, R. S. Williams., g2j. 



• Equisetum robustum A. Br.; Engelm. Amer. Journ. Sci. 46 : 88 

 [Man. R. M. 446 ; Our Native Ferns, 135 ; 111. Fl. i : 38 ; Bot. 

 Cal. 2 : 330], 



In rich, wet soil, especia,lly among bushes, up to an altitude of 

 1500 m. 



Montana: West Gallatin, 1892, W. T. S/iazc. 

 Yelloavstone Park : Hot Sulphur Springs, Adams. 



Equisetum hyemale L. Sp. PL 1062 [Man. R. M. 446 ; Our Na- 

 tive Ferns, 135 ; 111. Fl. i : 38 ; Bot. Cal. 2 : 331]. 



