ANON ACE JE. 



249 



even with, their edges not at all in contact. In the corolla the 

 aestivation has served to distinguish considerable groups, such, for 

 example, as the Unonefe and JJvariece. But on this point we must 

 insist less than most authors ; for in the genus Uvaria some species 

 have both corollas imbricated, others the one imbricated the other 

 valvate ; Anona, whose petals are usually valvate, may have them 

 most markedly imbricated,' as is the case too in certain Unonas of 

 the group Pol^alihia." 



2. The conformation of the pieces of the perianth, their form and 

 relative size. — This character is another which has been placed in 

 the first rank, having been used by Bentham & Hooker to estab- 

 lish all their tribes except one ; and these botanists have, as we have 

 seen, distinguished the three corollas which they term of the JJiionece, 

 Xylo}ne(2, and Mitropliore(B. That these forms are well marked 

 towards the culminating points of these groups is incontestible, 

 and hence we have avoided neglecting such a character in the sub- 

 division of the great group Anonca into minor sections. But we 

 have not founded true series on it, because tliere is one common type 

 of structure towards which all these forms gradually converge, so 

 that we get stages in which we cannot surely distinguish the Uno- 

 nean type of corolla from the Mitrophorean or Xylopiean, Of 

 this we have cited numberless proofs ; here it will be sufficient to 

 recall the fact that in the Melodornm group alone (including Pyra- 

 midantlui) there are at the same time corollas of Unoiia and Xylopia, 

 and that we find the same thing in Anona, Bocayea, &c. ; while 

 the conformiation of the perianth of Popowia has caused it to 

 be classed by some among the UnonecB^ by others among Mitre- 

 jjhorcce.^ Thus, again, it is because structural characters derived 

 from the relations of form and size stated to occur in the diiferent 

 pieces of the perianth are by no means absolute, that we have 

 proposed as of practical utility and convenience, though in no 



' See especially what we liave said relative to 

 the corolla of A. muricata (p. 222). 



^ We know, and shall at some future time de- 

 scribe several Old World plants that can hardly 

 be referred elsewhere than to PohiuUhia, though 

 their petals are distinctly imbricated. It may 

 be easily divined how they are also closely allied 

 to the genus Canauf/a iGualleria). I'eriiaps, 

 then, the future will compel us to recast certain 



genera, and will no doubt lead to a fresh reduc- 

 tion in their total number. 



3 T?. 11., Gen., 25, n. 19. It is true that the 

 authors add to their description : " Gfiiiis rix rile 

 llmitalum." 



•> Hook. F. & Tiioms., Fl. Lnl, i. 105. Cer- 

 tainly the corolla of the Asiatic species is in most 

 cases rather that of the Fhaanihea- tlian that 

 of the MUrepliore(E proper or tlie Viiohkc; but 

 they cannot be sepai-atcd from the African species. 



