Centaurea. COMPOSITE. 421 



white beneath with a close coat of cottony wool : heads solitary (or rarely clustered) 

 at the summit of the branches, at tirst nodding (about an inch high) : scales of the 

 involucre nearly glabrous (or .slightly woolly when young, but wholly destitute oi 

 jointed hairs), most of them terminated by a conspicuous and pectinately lacerate 

 ovate or lanceolate scarious spreading appendage, tipped with a short prickle or 

 cusp : corolla unequally cleft, the four more united lobes considerably shorter than 

 the throat : anther-tails laciniate. — G. scariosum, Xutt. 1. c. 



Marin and Mendocino Counties, Samuels, Bolander, Kellotjrj, &e. Also in the Rocky Moun- 

 tains of Colorado. Apparently not distinct from the Caucasian ami Siberian C carlinoides, 

 Schrank, Hon. Monac. t. 11 (jEWI t . I ass., DC. Hort. Genev. t. 22), 



although the outer scales of the involucre are not spinosely fringed, nor so prickly-pointed, 

 and sometimes are not at all appendaged. If distinct, Nuttall's name of scariosus could be used. 

 His description seems best to accord with Hall and Harbour's No. 5oD, which looks very much 

 like a hybrid between C. cnrlinoides and C. rcmot if alius. 



C. Paukvi, Gray, 1. c, of the Colorado Rocky Mountains, is another species of this section 

 verging to the preceding. 



105. SILYBUM, Ga-rtn. Milk-Tuistle. 



Head many-flowered, with leafy-bracted spinose involucre ; the flowers all perfect 

 and fertile. Filaments smooth and monadelphous. Pappus of stiff and almost 

 chaffy bristles in several series, not plumose. Leaves blotched with white. Other- 

 wise as in common Thistles. 



1 . S. Marianum, Gaertn. A stout annual, nearly glabrous : leaves large, ob- 

 long or obo'vate, sinuate or pinnaiifid and prickly-margined, clasping: head very 

 large, solitary : flowers pink-purple or red. 



San L lis Obispo, on rocky hills, and probably elsewhere : a native of the Mediterranean region, 

 introduced, probably through cultivation. 



106. CENTAUREA, Linn. Star-Thistle. 



Head many-flowered ; the flowers all with tubular and deeply 5-cleft corollas, 

 some of the marginal ones commonly neutral (and often with their corollas en- 

 larged) ; the others perfect and fertile. Involucre globular] the scales tipped or 

 margined with .-[pines or a scarious appendage. Receptacle very bristly. Akcnes 

 mostly compi 1, attached by one margin just above the base. Pappus of numer- 

 ous rigid or sometimes chaffy naked bristles. — Herbs of various aspect ( -500 to 

 400 species), marly all of the Old World, whence two have reached California as 

 weeds of cultivation ; both species destitute of the "false cays," i. e. their marginal 

 neutral flowers not enlarged and conspicuous. 



1. C. Melitensis, Linn. Annual, a foot or two high, paniculately branched. 

 roughish-pubescent, and when young with a little deciduous wool i leaves broadly 

 linear; the radical pinnatilid : cauline barely toothed or entire, decurrent: heads 

 rather small: most of the scales of the involucre tipped with a spine which is 

 fringed at base with a few prickles: corollas yellow, not enlarged. 



Old fields and waste grounds ; common on the western borders of the State : introduced from 

 Southern Europe. 



2. C. solstitialis, Linn. Annual, loosely white-woolly : cauline leaves linear: 

 beads larger than in the foregoing: outer scales of the involucre with 3 to •"> palmate 

 small prickles at the tip; the middle ones with a long and stout spine in addition : 

 corollas more conspicuous, yellow. 



Fields, Oakland , San Diego (Palmer), and probably elsewhere near the coa 



weed "i • ultivation ; introduced from Southern Europe. 



