n INTRODUCTION. 



knowledge wtich I do not myself possess ; but T am anxious to communicate 

 to him everything that I know myself. Where I have added the name of the 

 author, without marking the description by inverted commas, it denotes that 

 the description is taken from that author alone ; either because he alone has 

 described the plant as existing within my limits, or at least that his is the plant 

 I particularly refer to, whatever discrepancy may exist between his description 

 and that of other writers. 



It will be perceived from this account that the work has no pretensions to 

 originality. My task has been to translate and harmonize, as well as I coidd, 

 the descriptions of diifereut botanists ; and I have added the result of my own 

 observations only where it seemed to be absolutely necessary : considering that 

 to give my own view would often have only been, to add one more to opinions 

 already too numerous. 



It will be found that I have sometimes, in these pages, used certain words in a 

 sense not generally adopted, or at least not generally explained. When Linnaeus, 

 in the ' Philosophia Botanica,' first gave names to the forms of leaves, he seems 

 to have had little more in view than the comparative length and breadth. Suc- 

 ceeding authors have modified this considerably, but without giving any distinct 

 explanation of these modifications. I have considered them as exhibiting two 

 series of forms. Round, oval, ohlong, linear, are essentially obtuse or subobtuse ; 

 and always so to be understood, unless the contrary is expressed. Elliptic and 

 lanceolate are in the same manner to be considered acute or subacute. The 

 ohlong leaf of the ' Philosophia ' is a very eccentric oval ; but Linnaeus himself, in 

 practice, seemed inclined to limit it to a form which exhibited some degree of 

 parallelism on the two sides ; and later writers have adopted this latter interpre- 

 tation ; sometimes almost without reference to the comparative length and breadth 

 of the object. Thus Bentham, in De Candolle's ' Prodromus,' describes the seeds 

 of Euphrasia as oblong, though the length is not much greater than the width ; 

 and Koch calls the divisions of the leaves of some species of Carduus and Cirsium 

 oblong, where the length of the undivided portion, to which alone the term can 

 apply, is hardly equal to the width. Ohlong, as applied to the whole leaf, still, 

 however, I think, indicates a length of four or five times the width (though in 

 the figm-e in the ' Philosophia' it is hardly three times) ; and in this way I have 

 employed it. 



Elliptic has been used by botanists in two difterent ways. It is applied to the 

 regular mathematical ellipsis, which I have called an oval ; and to a form like the 

 symbolical fish of the middle ages, produced by two curves, each less than the 

 half of a circle, or of a true ellipsis, and uniting in an angle at each end. It is in 

 this sense alone that I employ it. My first notion was to keep to the mathematical 

 use of the tenn ; but the difficulty of finding a suitable name for the latter form. 



