Rydberg: Studies on the Rocky Mountain Flora 501 



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in the longer calyx and 



in the short corolla lobes. The specimens of northeastern America 

 seem to be like the European plant. In the latter the bracts are 

 only 4-6 mm. long, acuminate, the calyx less than three fourths 

 the length of the tube of the corolla and the lobes of the latter 

 4-5 mm. long. P. Americana grows in swamps and wet meadows 

 of the Rocky Mountain region at an altitude of 1200-2500 m. 



Montana: Deer Lodge, 1895, P. A. Rydberg, 2746 (type). 



Wyoming: Little Laramie River, 1896, Aven Nelson, 196 1 ; 

 Hams Fork and La Barge, J900, C. C. Curtis. 



Alrerta: Devil's Head Lake, Banff, 1899, IV. C. McCalla, 

 2422. 



Colorado: North Park, 1896, Geo. E. Osterhout 



■ Cuscuta gracilis sp. nov. 



Stem filiform, about .25 mm. in diameter. Flowers in dense 

 globular clusters : calyx gamosepalous but cleft to near the 

 base, lobes ovate : corolla urceolate, less than 2 mm. high, lobes 

 ovate, widely spreading, acute, delicate, about 1 mm. long ; scales 

 ovate, crenate, not divided, almost half as long as the corolla-tube : 

 filaments subulate, about twice as long as the anthers : styles dis- 

 tinct, equal, about as long as and somewhat thicker than the red 

 filiform curved stigmas : capsule about 2 mm. high, acute-globose, 

 circumscissile near the base : seeds about 1 mm. long. 



This species is nearest related to C. epilinum, which, however, 

 has shorter and broader corolla-lobes, shorter filaments, scarcely 

 longer than the anthers and short emarginate and crenate scales. 

 C gracilis grows parasitic on species of Erigerou, Chrysothamnus 

 and Solatium. 



Wyoming : Rolling plains between Sheridan and Buffalo, 1900, 

 F. Tweedy \ 3292 (type) ; Laramie, 1894, Aven Nelson, 11 39. 



m 



Stem stout, usually over 1 mm. in diameter. Flowers in dense 

 globular clusters : pedicels very short, at most 2 mm. long : 

 calyx gamosepalous, lobes rounded, scarcely 1 mm. long : corolla 

 about 3 mm. high and broad, lobes broadly triangular, acutish, 

 about 1 mm. long, with incurved tip ; fringed scales attached near 

 the bottom, equalling about half the corolla-tube, deeply 2-lobed, 

 and fringed only in the open sinuses : stamens about as long as the 

 lobes of the corolla, filaments subulate, about twice as long as the 



