INTRODUCTION. XXV 



certain orders are characterised. Thus Sapindacese and Polygaleas 

 have a calyx constantly irregular ; many orders are constantly 

 regular ; but it frequently happens that both regular and irregular 

 calyces co-exist in the same order, as in Rosacese, Labiatse, Legu- 

 minosae, and a great many others. — In most orders the sepals occupy 

 one series or verticillus only; others have them in two series, and 

 this has not been found to be connected with any material differences 

 otherwise ; but when the number of series is increased much beyond 

 two, they cease to be separately distinguishable, and form an imbri- 

 cated calyx, which is frequently confounded with the corolla, as in 

 Calycanthege and Wintereai. 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 Rosacese. — The most important character con- 

 nected 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 characterised by this, as Com- 

 positse, Umbelliferse, Capri foliacese, Orchidese, and very many more ; 

 and, as it usually happens that it exists without exception, it be- 

 comes 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 Rosacese, Scaevoleae from Brunoniaceae, and Cinchonaceaj 

 from Apocyneaa. No instance of a superior calyx has been found 

 in Ranunculacese, Cruciferse, Papaveraceas, 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 Anacardiacese, which 

 have almost universally a superior ovarium, a genus is said by 

 Mr. Brown to exist in which it is inferior ; in Melastomacese all 

 degrees of cohesion take place between the calyx and the ovarium ; 

 and in Saxifrageae this uncertainty of structure is still more remark- 

 able. It should, however, be observed, 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 Par- 

 nassia, an anomalous genus which is referred to Saxifrageae, 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 iTom 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 



