312 THE COMPOSITE FAMTLT. 



1. Alpine Saussurea. Saussurea alpina, DC. 



{Serratula, Eng. Bot. t. 599.) 



Stem erect aud simple, seldom a foot liigh, covered, as well as the invo- 

 lucres and under side of the leaves, with a loose cotton, which wears off with 

 age. Leaves from ovate to lanceolate, entire or toothed, 2 to 3 inches long. 

 Flower-heads ovoid or oblong, nearly sessile, in a small, dense terminal 

 corymb, with purple florets. The soft, feathery pappus projects beyond the 

 involucres, the inner bracts of which are softly hairy. 



In liigh northern latitudes, or at considerable elevations in the mountain- 

 ranges of Europe, Russian Asia, and Arctic America. Frequent in the 

 Highlands of Scotland, and found also in North Wales and the Lake dis- 

 trict of northern England. 



XXIV, THISTLE. CARDUUS. 



Herbs, with hard stems. Leaves often cut, and usually very prickly. 

 Involucres globular or ovoid, the bracts numerous, closely imbricated, and 

 usually prickly. Receptacle thick, bearing bristles between the florets. 

 Florets all eqvial and tubular. Achenes glabrous, with a pappus of nume- 

 rous simple or feathery hairs longer than the achene itself. 



The largest and widest-spread genus among Thistle-heads, for although 

 the species are chiefly European and Asiatic, yet there are also several 

 from Nortli America, and the common ones accommodate themselves 

 readily even to a tropical climate. They ai-e usually divided into two genera, 

 the plume Thistles {Cirsium or Cnicus) with a feathery pappus, and the 

 true Thistles with a simple-haired pappus, but the distinction is so purely 

 artificial that several botanists now revert to the old natural hmits indicated 

 by Linnaeus. 



Pappus consisting of simple hairs (Teue Thistles) . 

 Bracts of the large involucre very broad at the base, with lateral as 



well as terminal prickles 1. Milk T. 



Bracts of the involucre lanceolate or linear, without lateral prickles. 

 Involucres {^lobular, large. 



Involueral bracts broadly lanceolate 2. Mush T. 



Involucral bracts linear 3. Welted T. 



Involucres ovoid or cylindrical 4. Slender T. 



Pappus consisting of feathery hairs (Plume Thistles). 

 Leaves decun'ent along the stem, forming priekly wings. 

 riower-heads all peduncled. 

 Flower-heads ^ew, near 1^ inches long. Stem winged and prickly. 



Root biennial 5. Spear T. 



Plower-heads not au inch long, in terminal corymbs. Leaves but 



little decurrent. Rootstock creeping 7- Creeping T, 



Flower -heads small, in dense clusters. Stem winged and prickly 6. Marsh T. 

 Leaves not decurrent, or 07ily very shortly so. 



Flower-heads sessile or on very short peduncles. 



Stems stout and branched (about 2 feet). Involucres large 



and cottony 8. Woolly T, 



Stems dwarf, or scarcely any. Involucres not cottony . . . 12. Dwarf T, 

 Flower-heads all peduncled. Rootstock perennial, often creeping. 



Flower-heads in terminal corymbs 7. Creeping T. 



Flower-heads growing singly on long peduncles. 



Leaves ciliate, not prickly, very white underneath . . . . • 9. Melancholy T, i 

 Leaves prickly, green, or with a loose white cotton under- 

 neath. 

 Leaves deeply pinnatifid and lobed. Flower-heads usually 



2 to 4 10. Tuberous T. 



Leaves toothed, sinuate, or shortly lobed. Flower-heads 



usually solitary or 2 only 11. Meadow T. 



