Iviii INTRODUCTION. 



Vites have the lobes of the calyx distinct and wide apart from a very 

 early period of their existence : but in Penaeaceae both valvate and imbri- 

 cate aestivation exists. — In some plants the sepals are all of equal size ; in 

 others they are very unequal either in form, direction, or texture; in ihe 

 former case they are said to be regular, in the latter irregular, and by this 

 difference certain orders are characterized. Thus Sapindaceae and Poly- 

 galeee have a calyx constantly irregular ; many orders are constantly regu- 

 lar; but it frequently happens that both regular and irregular calyces 

 co-exist in the same order, as in Rosacese, Labiatae, Leguminosae, and a 

 great many others. In most orders the sepals occupy one series of verti- 

 cillus only ; others have them in two series, and this has not been found to 

 be connected with any material differences otherwise ; but when the num- 

 ber of series is increased much beyond two, they cease to be separably dis- 

 tinguishable, and form an imbricated calyx, which is frequently confounded 

 with the corolla, as in Calycantheae and Wintereas. I know of no order 

 in which genera with an imbricated calyx of this kind and a calyx of the 

 common kind co-exist. It is one of the principal points which separate 

 Calycantheae from Rosaceae. — The most important character connected 

 with the calyx is, however, its cohesion or non-cohesion with the ovarium; 

 or, as botanists incorrectly call it, its being superior or inferior. Many 

 orders are positively characterized by this, as Compositae Umbelliferae, 

 Caprifoliaceae, Orchideae, and very many more ; and, as it usually happens 

 that it exists without exception, it becomes one of the most useful means 

 of distinction of which we are in possession. Pomaceae are, for instance, 

 by this means at once known from Rosaceae, Scaevoleee from Brunoniaceae, 

 and Cinchonaceae from Apocyneae. No instance of a superior calyx has 

 been found in Ranunculaceae, Cruciferae, Papaveraceae, Rutaceae, and a 

 number of others. But there are some singular exceptions to this law. 

 Thus, among Anonaceae, an order with indefinite superior ovaria, we find 

 Eupomatia, in which they are inferior. In Anacardiaceae, which have 

 almost universally a superior ovarium, a genus is said by Mr. Brown to 

 exist in which it is inferior ; in Melastomaceae all degrees of cohesion take 

 place between the calyx and the ovarium ; and in Saxifrages this uncer- 

 tainty of structure is still more remarkable. It should, however, be ob- 

 served, that in the two latter orders the tendency to cohesion between the 

 calyx and ovarium may be almost always ascertained by careful dissection ; 

 and even in Parnassia, an anomalous genus which is referred to Saxifra- 

 geae, usually having an ovarium completely superior, there exists a species 

 in which it is partially inferior. I have said that the difference between a 

 superior and inferior calyx consists only in the cohesion of that organ with 

 the ovarium in the one case, and its separation from it in another; and 

 this is the view which is always taken of it, all that part which intervenes 

 between the segments and the pedicel being considered the tube of the 

 calyx. But I strongly suspect that we have yet to learn that theory has 

 in this case carried botanists too far, and that there are cases in which 

 the apparent origin of the calyx is the real origin. Upon this supposition, 

 what is now called the tube of the calyx may be sometimes a peculiar 

 extension or hollowing out of the apex of the pedicel, of which we see an 

 example in Eschscholtzia, and of which Rosa and Calycanthus, and per- 

 haps all supposed tubes without apparent veins, may also be instances. In 

 this case the whole of our ideas about superior and inferior calyxes will 

 require, modification. But upon this subject I cannot enter here : I have 



