114 NATURAL HISTORY OF PLANTS. 



Pitfo8porra>. Finally, Bentham & Hooker' have recently divided 

 the order into three tribes, DcVimea, Dillenina, and Hihbcrtiea^ 

 based on the form of the anthers. We have elsewhere attempted 

 to show^ how this classification, often serviceable in practice, is 

 yet by no means exact, and how the same form of stamen may be 

 observed in genera of any of the three tribes indifferently. Hence 

 we have tried to establish a certain number of series, of which the 

 respective genera have been described above, and which are founded 

 first on the general structure of the gyna?ceum, and then on that 

 of the androceum. DUlenia is in our eyes the prime centre around 

 which are grouped the genera in which the carpels are more or less 

 united into a plurilocular ovary, while at the same time the stamens 

 are indefinite. In all the other Dilloiiacca the carpels are inde- 

 pendent of one another, and the unilocular ovaries have a parietal 

 placenta in the inner angle. But among these the stamens 

 may be indefinite as in Hihhertia, or twice as numerous as 

 the petals, or grouped in exactly as many bundles as there are 

 pieces in the perianth, as occurs in CandoUea. Thus Hihhertia 

 and CandoUea become two other centres or heads of series, usually 

 easy to separate in practice, but between which we should be the first 

 to recognise that there are inevitable points of contact, such as are 

 always found in orders like the one under consideration.^ 



' Oenera, 10, 11. club-shaped head (fig. 144); the outermost 



- Plaxcuon Las reproduced (see de Linden, stamens, vcrj- short, may be quite sterile. In T. 



3, 4) the opinions of the English authors, and sarmeniosa, the tiluments are free, or slightly 



admitted their three principal groups; but he coherent at the base. In Lavilla nigosa we 



makes a fourth for the genera Wurmia, Aero- have seen introrse and extrorse anthers in the 



<re»ia, and Schumaclteria, which, he says, "are bud. Acrotrema, which is said to have " 5/a- 



more or less abnormal, and do not tit well in any minumfilamenta hand dilafa," may have parallel 



ot the divisions," We have shown (.^rfaMwnia, vi. marginal anther cells, or a connective swollen 



276) in what this assertion is too absolute, and into a head like Tetracera (tig. 151), or the 



how closely analogous are Wormia and Uillenia, anther cells may be porricidnl and close together 



Schunuulieria and Jlemislemma, Acrotrema and for their whole length (fig. 152). The Hibbertiat, 



Tetrncera, at least in fiower and fruit. in which the cells are long, narrow, pandlel, and 



' Adansoniu, vi. 209, 278. In several 2Hra- close together (fig. 130), nniy have anthers with 



ceras and iJaviUoji the same Hower contains one- short, dilated connectives, and short colls, like 



and two-celled extrorse and introrse anthers. We those of Tetracera (see fig. 131). Such occurrencea 



have been shown several flowers of T. sene- have been jwinted out by F. MVEU.KK (^nyw., 



^a/«wi*, which had introrse anthers to the inferior ii. 2), especially in 11. fiellaris, of which the 



stamens, while all the superior or innermost anthers are broader than they are long, 

 stamens had extrorse antlieni. In T. obovata, * Thus we have shown how the liibb<rtie(t 



the summit of the filament swills into a connec and the Delimen; come tlm)ugh Trisema and 



tive of variable form, wjuietimes entire, sometimes iJilimti respectively to i)resent tlie same perianth, 



bifid to a variable extent; the cells are then home the same ajidroceum with indefinite elenieutii, 



on distinct branches (fig. IKJ). In T. volubilis, mid the same gyna-ceum. We have also re- 



the stjimens are all unlike. Th.- connective swells cognised the common hnks Mwecn -i<-ro/rri»(i 



gradually, or suddenly, into an obpyramidal, or uwXSchumucheria,&\\Ai\\i: DiU<rnU,r,Tetritcrrr<r, 



