250 NATURAL HISTOIiY OF PLANTS. 



way essentially natural, the establishment of a group Militusccp, 

 where the outer petals are, as we have seen, far more similar to 

 sepals than to the pieces of the inner corolla. We knew in fact 

 that there were genera foreign to this group, such as Popovin, 

 Mifrrjj/iora, and Ornphaa, in certain species of which the outer 

 petals were already becoming in form and size less like the inner 

 petals, and so were tending to approach the calycine leaves. 



3. The absence of the inner petals is of itself insufficient to cha- 

 racterize a genus, for there are genera, recognised as perfectly 

 natural, where the outer petals gradually become much smaller 

 than the inner ones, and before finally disappearing are even reduced 

 to very small spoon-like bodies. We may cite certain species ol' 

 Aiioiia, Bolli/iia, and one abnormal lioUinia of the section Clut/iro- 

 Hpennui/i. Most species of Ununu liave a well-developed corolla ; but 

 in some it is quite absent. 



4. The independence or union of the pieces of the perianth has 

 never appeared to us sufficient to characterize a genus. Hexahhu^ 

 for instance is not merely Unona with a gamopetalous corolla ; other 

 features mark it out, and we have sketched them.' But it is 

 impossible to make a generic distinction between those species of 

 Uvaria, Unona, and Bollinia, in which the corolla comes off in a single 

 piece, and those other species of these genera whose structure is 

 otherwise quite the same.^ The corollas of the Monodoras, varying^ 

 fzreatly in form, are all gamopetalous ; but this feature alone would 

 not be thought worthy to put them in a group apart, if the peculiar 

 organization of their gyna?ceum did not give them so marked a dis- 

 tinction.^ Nor is the union or freedom of the calyx-leaves a cha- 

 racter of more value ; for it may happen that of two species of the 

 same genus, as closely allied as possible, the one may have free 

 sepals, the other an urceolate calyx, v;ith three teeth hardly i)ro- 

 jecting on the edge. 



5. The number and arrangement of the stamens. — We have 



' Sec p. 226. It might not, however, he ini- dmled in Tii()tineia hy Hkntuam k HooKKB, 



poKsiblc to moot with Homc H|KK-ic8 wliich HhouUl thougli itii coruliii is (U>cidi>(lly ^unoiwtiilotii*. 



conncol tliis pcmm witli one of the hections ol * Wo shouhl liiithor imtiio llio tt)UsiH|uoncc 



Artabutrya. For tho jiroMiit llio iinion ol" tlio of gamopotaly in this gonus; it is that the throo 



potulH is ut once Huflieicnt to dintingniith the diviitionH of tlie corolla !injK.'riK)«o«l to tho Hoiwlii 



gcnom. nniy linully ajipcar to stand on tho same verticil 



■•I It is no doubt forlhemimcrciuKn that //fj-H- as the three outer ones. Probably this is not 



lobun brasHiennis A. S. H. A Iri.. Iins hren in- the casf when they are young. 



