336 NATURAL HISTORY OF PLANTS. 
colouring. It is however certain, the mode of insertion, and the 
organization of the ovules are very different in Cistacee and Dilleni- 
aceæ ; if not, we might consider the former as representing a form 
of carpels united edge to edge in a unilocular ovary, while the latter 
would have, in general, independent and unilocular carpels, and 
would be to Cistacee what I/licee is to Canellee, Anonee to Mono- 
doree, Astrocarpee to Resedeæ, &e. The false racemes of Helianthe- 
mum, compared with the unilateral inflorescence of certain species of 
Mibbertia, would singularly complete the analogy between the two 
groups. On the other hand, Cisfaceæ has been placed by most 
authors near Capparidaceæ, Resedacee, and Bixacee. They have not 
the habit, corolla, anatropous or campylotropous ovules, nor the 
seeds of either of them. They cannot always be absolutely distin- 
guished from all the Capparidaceæ, by the presence of an albumen, 
since certain of them are also provided with it. But in Cistacee it 
is either farinaceous or subcartilaginous. The orthotropy of the 
seeds, and the more or less pronounced curvature of the embryo, 
often convolute and conduplicate, serves, however, to distinguish 
Cistacee from Bivaceæ. The latter have sometimes a calyx, with 
unequal sepals, with two small bractiform and exterior leaves, as in 
so many species of Helianthemum, such as Ryania, which is, moreover, 
destitute of petals. The /7o/acee are correctly considered as nearly 
allied to Cistacee ; but they have either irregular flowers, or when the 
corollais regular, a definite number of stamens and ovules, and seeds of 
quite a different character. The polypetalous Canellee@ have almost 
the same organization as the Cistacee as to perianth and placenta- 
tion; but their monadelphous stamens, fleshy fruit, and anatropous 
seeds are totally different in character. There are also analogous 
resemblances between Zuvemburgiee and Cistacee ; but the former 
has a characteristic foliage, an eccentric gynæceum, and anatropous 
ovules. We may say, in short, that Cis/aceæ, a syncarpous form of 
Dilleniacee ?, is a connecting link also between Bivacee and Violacee. 
Turnereæ, which we have, moreover, connected with Bixacee, is also 
very analogous to the Cés/aceæ by its corolla, mode of placentation, 
and capsular fruit; it is distinguished from them particularly by 
the definite number of its stamens, and often also, but not con- 
stantly, by the difference in their mode of insertion. 
