586 CLASSIFICATION AKD DIVISION OP 
alternate leaves, and a large proportion of them have a 
paleaceous receptacle, and the rays of the pappus con- 
nected at the base, — all of which appear incontestibly to 
prove that they cannot with propriety be removed from 
the Carduacece ; but it is, however, to be observed^ that 
the latter have the tube of their florets suddenly con- 
tracted from near the middle downwards ; while in Gria-, 
jphalium and Hellclirystim^ and in the other genera which 
have been separated from them, the tube of the florets is 
nearly equaL. or gradually narrowed downwards from the 
summit to the base, as in the CarlinecB of M. Cassini. 
This character, although perhaps of generic importance, 
(Cannot be assumed as the foundation of a separate group, 
being liable to considerable variation. Thus, for example, 
Cnicus Acarna^ Carduus cernuus Carthamiis tinctoriuSy 
and Cardims unjflorus, agree with the Carlinece in the form 
of their florets ; and in Cnicus serrahdoides, Carduus cya- 
noides and palustris, the contraction of the tube is scarcely 
perceptible. In Xeranthemum and Chardinia the tube of 
the florets is widened towards the base, and contracted up- 
wards. Had the form and structure of the stic^mas in Heli- 
cJii'ysum, GiiaphaUum, &c. been uniformly constant, they 
would have assisted materially in distinguishing them as a 
separate group. The genus Carlina agrees in its stigma 
with Xeranthemum, and with Astelma of Brown, in having 
the rays of its feathery seed-crown united into bundles for 
a considerable way above the base. The similarity of the 
pappus of Acarna to that of Metalasia, is equally striking. 
In Carlina acaidis and simplex, as well as in Atractylis 
gummifera, which really belongs to Carlina, the rays of 
the pappus are so remarkably thickened at their extremi- 
* This plant M. Cassini has constituted into a genus, named by him 41-' 
frediap and h^s arranged it among the Carlinece^ 
