Partki-nium. COMPOSITiE. 285 



Also a native of Mexico and the West Indies. — Leaves resembling those of 

 Ambrosia artimesicEfoIia. 



§ 3. Pajijnts of 2 oblong-lanceolate membranaceous squamellce, nearly the 

 length of the short truncate tubular corolla: ccespitose, dwarf: heads soli- 

 tary and nearly sessile among the spatulate-Unear canescent leaves at the 

 summit of each division of the ligneous caudex ! — Bolophyta, Nutt. 



3. P. alpinum. : acaulescent ; caudex branched, denselv c^sspitose, and 

 crowned with the vestiges of former leaves and whh a tuft of white hairs ; 

 leaves densely tufted, entire, silverj^-canescent ; corolla of the ray scarcely 

 exserted, truncate, slightly 2-crenulate. — Bolophyta alpina, Nutt. ! in trans. 

 Amer.j)hil. soc. (n. ser.) 7. p. J347. 



In the Rocky Mountains, towards the sources of the Platte, in about lat. 

 42°, on slielving rocks at the summit of a lofty hill, near the place called the 

 ' Three Butes' by the Canadians, 7000 feet above the level of the sea. Ntit- 

 tall! June. — Caudex fusiform, sending off several closely matted crowns of 

 leaves ; the latter an inch or an inch and a half in length, scarcely a line 

 wide, tapering into short petioles, 1-nerved. Heads concealed among the 

 leaves, about as large as those of P. integrifoliiim, and entirely similar in 

 structure ; except that the rays, if they may be so called, are shorter, entirely 

 tubular, with an obscure emargination anteriorly and posteriorly. The pap- 

 pus, which escaped Mr. Nuttall's notice, consists of a scarious ovate-lanceo- 

 late or triangular scale-like auricle or tooth on each side, which perhaps 

 withers away as the achenium ripens. Excepting the habit, therefore, we 

 find nothing whatever to distinguish this little plant from Parthenium, be- 

 yond the more reduced corolla of the ray. 



Div. 5. IvE5:, DC. — Fertile and sterile flowers in the same heads, all 

 tubular, or the former rarely apetalous. Pappus coroniform, 4-awned, or 

 none. Anthers approximate but distinct : filaments inserted towards the 

 base of the corolla. Style of the fertile flowers mostly 2-parted. 



77. CYCLACH^NA. Fresenius, ind. sem. hort. Franc. 1836, p. 4, Sfin 

 Linntea, 12, suppl. p. 78. 



(Polygamo-subdioecious ; the barren plant similar to the fertile, but not 

 fertilizing its ovaries.) Fertile and sterile flowers in the same heads ; the 

 former 5, in the axils of the inner scales of the involucre, with no corolla or a 

 mere rudiment ; the latter 10-15, with an obconical 5-toothed corolla, (near- 

 ly destitute of proper tube) ; the central ones abortive. Scales of the flattish 

 hemispherical involucre usually TO, in 2 series ; tlie exterior 5, ovate, some- 

 what acuminate, thickish, herbaceous ; the interior dilated-obovate, truncate, 

 membranaceous, at length loosely wrapped around the achenia. Recepta- 

 cle small, flat ; the chafTlinear-spatulate, usually wanting towards the cen- 

 tre. Anthers slightly united, tipped with an inflexed mucronate appendage. 

 Style of the fertile flowers deeply 2-cleft, linear, acutish ; in the sterile 

 flowers undivided, radiate-penicillate at the apex. Achenia obovate, obcom- 

 pressed, somewliat turgid, not margined, glabrous, entirely destitute of pap- 

 pus ; tlie siaminafe (lowers with no rudiments of ovaries. — A tall and coarse 



