Nineteenth class. 
39 
— Receptacle without scales (in Filago there are, between 
the outer florets, scales resembling invol.-bracts) 39 
28. Inner invol.-bracts scarious, coloured (rayed) . 29 
— Inner invol.-bracts not rayed .... 30 
29. Rayed invol.-bracts white or yellowish white. Pis prickly. 
Ls sinuate or pinnatifid . . . Carlina. 328. 
— Rayed invol.-bracts rose-coloured. Pis not prickly. Ls 
entire, tomentose .... Xeranthemum. 334. 
30. Invol.-bracts in 2 rows. Ls opposite . Bidens. 305. 
— Invol.-bracts imbricate. Ls alternate . , . . 31 
31. Invol.-bracts (the inner ones sometimes excepted) atten¬ 
uated to a hooked point (heads consequently clinging 
to anything they come in contact with). Ls denticulate, 
the lower ones very large, 3—4 dm broad Lappa. 327. 
— Invol.-bracts not attenuated, terminated by a straight 
spine or a scarious appendage . . . . 32 
32. 
33. 
34. 
35. 
36. 
37. 
38. 
39 
Silybum. 324. 
. 33 
. 31 
35 
Filaments of the stas united 
Filaments of the stas free 
Pappus plumose 
Pappus of simple hairs . 
Invol.-bracts and ls without prickles (Alpine pis with 
rose or violet fls). Saussurea. 329. 
Invol -bracts terminated by a spine of some length. Ls 
spiny or at any rate ciliate-spiny . Cirsium. 323. 
Pappus-hairs united at the base and falling off together 
at last. Ls decurrent .... Carduus. 325. 
Pappus-hairs falling off separately . . . 30 
Outer invol.-bracts leaf-like . . Kentrophyllum. 331. 
Outer invol.-bracts not leaf-like .... 37 
Pappus-hairs arranged in several rows, the innermost 
series longer than the others . . Serratula. 330. 
Pappus-hairs arranged in several rows, the innermost 
series shorter than the last but one . . . 38 
Fr. with lateral hilum .... Centaurea. 332. 
Fr. with basal hilum .... Crupina. 333. 
(27). Invol.-bracts arranged in a single row, equal in 
length, or accompanied at the base by some shorter 
bracts forming an outer involucre . . . 10 
Invol.-bracts imbricate, the outer ones gradually dimin- 
40. 
41. 
42. 
43 
ishing in length 
Stem leafless (scaly) 
Stem leafy 
Stem with 1 head . 
Stem with many heads 
Fls purple 
Fls yellow 
(39). Ls opp. 
Ls altern. 
13 
. 11 
. 12 
Homogyne. 288. 
Petasites. 290. 
Adenostyles. 287. 
Senecio. 320. 
Eupatorium. 286. 
11 
