296 DESCRIPTIONS OF NEW SPECIES 



Tripolium * Oregonum, stem rather tall, fiexuous, and divaricately branched ; 

 cauline leaves long, linear, sublanceolate, nearly equal, acute, entire, scabrous 

 on the margin; sepals linear-lanceolate, imbricate, slightly acute, herbaceous; 



rays narrow. 



Hab. On the inundated banks of the Wahlamet; flowers very inconspicuous, somewhat fas- 

 tigiate. 



Tripolium * divaricatum, stem rather naked, slenderly and divaricately 

 branched ; radical leaves spathulate, or lanceolate, subdenticulate ; stem leaves 

 above, very short and subulate, clasping; sepals subulate, acuminate, scariose, 

 imbricate, and somewhat equal; achenium smooth, with four striae. 



Hab. Inundated banks of the Mississippi, and in Louisiana, not uncommon. Very smooth, the 

 radical leaves thick, flowers rather conspicuous, rays blue. Remarkable for its divaricate and 

 naked branches. A plant very similar occurs on the coast of Cuba. 



Tripolium * occidentale, stem nearly simple, few-flowered, flowers large and 

 corymbose; leaves all linear, subulate amplexicaule, here and there incisely 

 serrate; involucrum loosely imbricate; sepals subulate, subherbaceous, nearly 

 equal; rays as long as the disk, (pale blue;) achenium nearly smooth, scarcely 

 striate, compressed. 



Hab. By the margins of muddy ponds in the Rocky Mountains, seven thousand feet above the 

 level of the sea. Root creeping, slender; stem slender, four inches to a foot high, often only one 

 or two-flowered, seldom more than five or six. Leaves long and narrow, linear, entire, or with 

 one or two pair of deep, incise serratures, almost approacing to a pinnatifid division; branchlets 

 slender, one-flowered. The flower as large as a daisy, with a simple series of pale blue, or pink 

 rays. An alpine species, approaching the true Tripolium in the fruit being almost destitute of 

 striation. 



Tripolium * frondosum, stem much branched, leaves linear, entire, amplexi- 

 caule, rather obtuse; capituli fastigiate ; sepals linear-oblong, loose and leafy, 

 rather obtuse; rays numerous, very small and slender; achenium nearly smooth, 

 about four-striate. 



Hab. By muddy ponds in the Rocky Mountains, near Lewis' River of the Shoshonee; rare. 

 Growing partly in the water and mud. Apparently biennial, succulent, with very inconspicuous 

 flowers, and an entirely leafy, nearly equal involucrum of about two series of leaflets. 



Tripolium subulatum. Allied to the preceding by its numerous small rays. 

 Achenium slightly pubescent, compressed, with five strige. 



