DICOTYLEDONS. 247 



2. C. spiNOSissiMus Walt. Yellow Thistle. Biennial or 

 perennial ; stem erect, stout, woolly when young, becoming smooth, 

 often purple, branched, l-o ft. high; leaves pinnatitid, with very 

 spiny teeth, mostly sessile and clasi>ing, smooth and green on both 

 sides; heads large, surrounded by a whorl of linear-oblong, pectinate 

 leaves; involucral bracts linear, ciliate, not spine-tipped; flowers 

 purple or yellowish. April-June. On sandv soil. 



XVII. THYRSANTHEMA. 



Perennial, acaulescent herbs ; leaves green above, white- 

 tomentose beneath ; scapes single or few, each bearing a 

 single head of white or purplish tiowers ; heads radiate, many- 

 flowered ; bracts imbricated in several rows, appressed, the 

 outer shorter ; receptacle naked ; ray flowers in 2 rows, pis- 

 tillate and fertile, the outer ligulate, entire or 3-toothed at 

 the apex, the inner 3-5-toothed, flliform, disk flowers perfect 

 but sterile, the corolla bilabiate, 5-toothed ; styles entire ; 

 achenes oblong, 5-nerved ; ])appus of numerous white hairs. 



T. semiflosculare (Walt.) Kuntze. Spkixg Daisy. Leaves 

 narrowly oval to spatulate, nearly prostrate, smooth above, densely 

 white-woolly beneath, entire ; scapes leafless, erect, slender, tomen- 

 tose, 0-12 in. high; heads about 1 in. wide, nodding in the bud, 

 Itecoming erect in flower; bracts lanceolate to linear; rays broa<lly 

 linear, ])inkish-i)nrj)le ; achenes narrowed at each end. smooth; Jtaj*- 

 ))iis of numerous bi-istle-likc hairs. February-A}»ril. Very common 

 on low iiTound. 



