AND GENERA OF PLANTS. 421 



plumose ; achenium smooth and even. The inner divisions of the involucrum, and, in fact, the 

 whole aspect of our plant is very similar to that of Echenais carlinoides, Avhich is also a true 

 Circium, without any vestige of generic character, or even habit, to separate it; for, on examining 

 the fruit when mature, I find it smooth and even, without any striatures whatever. 



Circium *megacanthum; glabrous, robust and gigantic; capituli round, ag- 

 gregated in clusters towards the summit of the stem; leaves deeply pinnatifid 

 and somewhat decurrent, segments lanceolate or linear-lanceolate, terminating 

 in stout spines nearly their length, the margin ciliate-serrate ; capituli bracteo- 

 late, involucrate, the bractes and upper leaves exceedingly spiny ; scales of the 

 involucrum lanceolate, acuminate, erect, acicularly terminated; pappus very 



long. 



Hab. On the banks of the Mississippi, in the vicinity of New Orleans. Found by Mr. Little 

 and myself. Its measurements, according to Mr. Little, are three to six feet high. Stem two 

 inches in diameter, at base; the largest leaves one foot four inches long: (a specimen from the 

 Bayou Road.) The leaves are sometimes slightly arachnoid along the mid-rib. The larger spines 

 are nearly an inch long, and as stout as coarse sewing needles. The clusters of capituli may be 

 from ten to twenty, about three inches wide, when largest; the sepals terminated with mere acicular 

 points. Pappus plumose, near one and a quarter inches long, white; tube of the floret twice as 

 long as the nearly equal border; anthers caudate, the appendage deeply cleft; cusps acuminate. 

 Resembles at first glance C. spinosissimum, but it is much larger, and wholly distinct. The seg- 

 ments of the leaves are long and narrow. One of the most terribly armed plants in the genus. 



§. VI. Onotrophe. (Cassini.) 



Circium *hrevifolium; stem slender, subterete, and, as well as the under 

 surface of the leaves, whitely tomentose; leaves oblong-lanceolate, amplexi- 

 caule, sinuately pinnatifid, with shallow, simple, or bifid lobes, ending in spines 

 and spinose serratures; involucrum ovate, naked; scales lanceolate, glutinous, 

 smooth, terminating in small, erect spines. 



Hab. In the Rocky Mountain plains. Allied to C. Virginiunum; but the leaves more divided 

 and far more tomentose, as well as the stem; the capitulum very similar. Stem terminating in two 

 or three capituli. Florets ochroleucous, unequally cleft. Anthers lacerately caudate. Pappus 

 plumose, with slender tips. Leaves about half an inch wide, two to three inches long, nearly 

 smooth, and green above. 



VII. — 5 F 



