250 THE COMPOSITE FAMTLY. [Garduus. 



Leaves ciliate, not prickly, very white underneath . 9. 6". keterophyllui. 

 Leaves prickly, green, or with a loose white cotton 

 underneath. 

 Leaves deeply pinnatifid and lobed. Flower-heads 



usually 2 to 4 10. C. tuberosum. 



Leaves toothed, sinuate, or shortly lobed. Flower- 

 heads usually solitary or 2 only . . , . 11. ft pratensis. 



Very anomalous specimens occur occasionally, especially among the 

 Cnicuses, which are generally believed to be natural hybrids. [These 

 are most frequent between G. palustris with heterophyllus and pratensis, 

 and between acaulis with pratensis and arvensis.] 



1. C. Marianus, Linn. (fig. 558). Milk T. — An annual or biennial 

 2 to 3 feet high, not much branched, and glabrous or with but very 

 little cottony wool. Leaves smooth and shining above, and variegated 

 by white veins ; the lower ones deeply pinnatifid with broad very 

 prickly lobes ; the upper ones clasping the stem by prickly auricles but 

 scarcely decurrent. Flower-heads large, drooping, solitary at the ends 

 of the branches, with purple florets. Bracts of the involucre very broad 

 at the base, with a stiff, spreading, leafy appendage, ending in a long 

 prickle, and bordered with prickles at the base. Hairs of the pappus 

 simple. Silybum Marianum, Gsertn. 



In waste places, in southern Europe to the Caucasus ; not indigenous 

 in central Europe, although it occurs here and there as a weed of 

 cultivation. Eare and only introduced into Britain. Fl. summer, 



2. O. nutans, Linn. (fig. 559). Mush T. — A stout species, 2 to 3 

 feet high, usually slightly covered with loose cottony hairs. Leaves 

 deeply pinnatifid, very prickly, their edges decurrent along the stem, 

 forming narrow very prickly wings. Flower-heads large and drooping, 

 as in G. Marianus, but often 3 or 4 in a loose corymb. Involucra] 

 bracts numerous, with a stiff, narrow-lanceolate appendage, ending in 

 a spreading or reflexed prickle, but without lateral prickles. Hairs of 

 the pappus simple. 



In waste places, common in the greater part of Europe and temperate 

 Asia, but not spreading to the extreme north. Pretty frequent in 

 southern England, especially on limestone soils, less so in the north, 

 and rare in Scotland. Occurs also in Ireland. Fl. summer. 



3. C. acanthoides, Linn. (fig. 560). Welted T. — Much resembles 

 G. nutans, but is usually taller and rather more branched ; the leaves 

 narrower and more prickly ; and the stem more thickly covered with 

 prickly appendages, decurrent from the base of the leaves. Flower- 

 heads not so large, though yet globular and slightly drooping; the 

 involucral bracts very numerous and narrow, ending in a linear, 

 spreading or recurved prickle, the innermost often of a thinner texture, 

 slightly coloured and scarcely prickly. Hairs of the pappus simple. 

 0. crispus, Linn. 



A very common Continental Thistle, extending eastward entirely 

 across Asia, and northward to the Arctic Circle, although in Britain, 

 like many others, it becomes scarce in Scotland. Fl. summer. Three 

 forms are often distinguished as species, G. acanthoides, Linn., with 

 few flower-heads, on long peduncles, and the leaves often nearly 

 glabrous ; 0. crispus, Linn. , with the heads clustered several together on 

 short stalks, and the leaves usually rather broader and more cottony 

 underneath ; and G. polyanf&emus, Koch., with crowded ovoid heads ; 



