40 
Nineteenth class. 
44. Prickly, thistle-like pis 
— Pis without prickles 
45. FIs all hermaphrodite 
— Outer fls female 
46. Fls yellow 
— Fls never yellow 
47 
. Onopordon. 326. 
. 45 
. 46 
47 
Linosyris. 291. 
. Antennaria. 310. 
Some, at least, of the invol. bracts scarious. (Tomen- 
tose or wooly-tomentose pis with indistinct fls) . 48 
— Invol. bracts herbaceous ..... 51 
48. Receptacle with bract-like scales between the fem. fls 
Filago. 307. 
— Recept. without scales ...... 40 
Heads all polygamous (on one stem all female, on the 
other all hermaphrodite) . . . Antennaria. 310. 
Heads with mixed fls (ray fls fem., disk fls hermaphro¬ 
dite) . . . . . . . . .50 
Pappus hairs of the disk fls thickened (like a club) 
49. 
50. 
towards the top 
Leontopodium. 309. 
Pappus hairs of all the fls filiform or only slightly 
Gnaphalium. 308. 
Conyza. 300. 
Erigeron. 296. 
Centaurea. 332. 
thickened towards the top 
51 (47). Fls yellow 
— Fls never yellow 
52 (26). Receptacle having scales 
— Receptacle, without scales, glabr. or hairy . . 53 
53. Heads isolated, terminal with divergent, reflexed bracts. 
Fr. beaked. Carpesium. 306. 
— Heads agglomerated or crowded .... 54 
54. Invol. bracts in 2 rows .... Micropus. 298. 
— Invol. bracts imbricate (comp, also Matricaria discoidea) 
55 
55. Heads small or very small, gen. in spikes or racemes 
arranged in a panicle .... Artemisia. 311. 
— Heads of moderate size, in a flat corymb. Fls yellow 
Tanacetum. 312. 
56 (1). Receptacle having scales ..... 57 
— Receptacle without scales . . . . 63 
57. Invol. bracts in 1—2 rows (Ray fls barren, yellow) 58 
— Invol. bracts in several rows (imbricate) . . 50 
58. Pappus short, crown-like. Ls altern. Rudbeckia. 303. 
— Pappus consisting of 2—5 awns armed with small re¬ 
flexed spines. Ls opp. .... Bidens. 305. 
59. Ray fls barren . . . . . . .60 
— Ray fls female ’ . . . . . . . 61 
60. Ray fls yellow. Heads very large. Ls undiv. 
Helianthus. 304. 
Ray fls white. Heads rather small. Ls 2—3 pinnatipar- 
tite .. Anthemis. 314. 
