444 DESCRIPTIONS OF NEW SPECIES 



Galathenium sanguineum. Lactuca smiguinea, Bigel. Flor. Bost., (ed. 2,) 

 p. 287. Leaves very often nearly all entire, or only runcinately toothed; ache- 

 nium one-nerved, black. 



Galathenium ludovicianum. Sonchus ludovicianus, Nutt. Gen. Am., Vol. II., 

 p. 125. 



Obs. The plants of this genus (peculiarly North American) appear to be 

 intermediate between Lactuca and Mulgedium. From Lactuca they differ 

 wholly in the achenium, which, in L. sativa and others, is of a pale colour, 

 and covered with longitudinal striatures. In Lactuca perennis, however, the 

 striatures are few, and the achenia has a tumid margin, as in Mulgedium, but 

 it is also furnished with a very long rostrum. From Mulgedium our plants 

 differ in the form, compression, colour, and margin of the achenium, as well 

 as in the presence of an abrupt and distinct rostrum, seldom, if ever, the length 

 of the elliptic fruit, and of a different colour and consistence with the ache- 

 nium. 



LYGODESMIA. (Don.) 



Subgenus *Pleiacanthus. — Capitulum four to five-flowered. Involucrum 

 cylindric-ovate, imbricate, of a few unequal, fiat, lanceolate sepals, the ex- 

 ternal so short as to appear like a caliculum. Receptacle minute, naked. 

 Achenium subcylindric, obtusely five-ribbed, truncated. Pappus bristly and 

 barbell ate, yellowish- white, long, and in several series. — A nearly leafless, 

 divaricately branched, rigidly spiny perennial, with rose-red flowers in short 

 racemes. Probably a distinct genus. 



Lygodesmia* spinosa; stem divaricate; bran chiefs spinescent, microphyllous; 

 capituli subracemose, with an irregular involucellum. 



Hab. In the Rocky Mountain plains towards California. About eight to fourteen itiches high. 

 Lower leaves linear, entire, sessile, rather thick; upper leaves and those on the spiny branchlets 

 minute, like very small bractes. Stem divaricate and spreading, the base somewhat pubescent and 

 producing remarkably large tufts of brownish matted down ; the bud scales broad ovate. Flowers 

 pedicellate, in racemes. Every branch and twig ends in a spiny point. Larger leaves of the in- 

 volucrum three or four, ovate, or ovate-lanceolate, three or four smaller ones at the base of the 

 involucrum. Florets rose-red, deeply five-cleft at the summit. Stigmas filiform, exserted, pubes- 

 cent. Pappus rigid and barbellated. 



