INTRODUCTION. 



I. Definitions. 



The principal object of a Flora of a country is to afTord the means of 

 determining (i.e. ascertaining the name of) any plant growing in it, whether 

 for the purpose of ultei'ior study or of intellectual exercise. 



With this view, a Flora consists of descriptions of all the plants contained 

 in the coimtry in question, so drawn up that the student may identify his 

 plant with the corresponding description. 



Tliese descriptions should be clear, concise, accurate, and characteristic, 

 so as that each one should be readily adapted to the plant it relates to and 

 to no other one ; they should be as near as possible arranged under natural 

 divisions, so as to facilitate the comparison of each plant with those nearest 

 allied to it ; and they should be accompanied by an artificial key or index, 

 by means of wliich the student may be guided step by step in the obsei-va- 

 tion of such pecuharities or characters in his plant, as may lead him, with 

 the least delay, to the individual description belonging to it. 



For descriptions to be clear and readily intelhgible, they should be ex- 

 pressed as much as possible in ordinary well-established language. But, for 

 the purpose of accuracy, it is necessary, not only to give a more precise tech- 

 nical meaning to many terms used more or less vaguely in common conver- 

 sation, but also to introduce purely technical names for such parts of 

 plants or foiins as are of httle importance except to the botanist. The ob- 

 ject of the present Chapter is to define all such technical or technically 

 limited terms as are in use in the present or in most other British Floras. 



At the same time mathematical accuracy must not be expected. The forms 

 and appearances assumed by plants and then- jjarts are infinite. Names can- 

 not be invented for all ; those even that have been proposed are too nume- 

 rous for ordinary memories. Many are derived from supposed resemblances 

 to well-known forms or objects. These resemblances are differently appre- 

 ciated by different persons, and the same term is not only differently apphed 

 by two different botanists, but it frequently happens that the same writer is 

 led on different occasions to give somewhat different meanings to the same 

 word. Nor can this be otherwise : beautiful as is the symmetry of structure 

 in plants, it is not one of rule and compass. Their parts are never precisely 

 regular, nor is the same part precisely of the same form in two individuals of 

 the same species ; and the botanist's definitions and descriptions must par- 

 take of tliis uncertainty. His endeavom* must be, on the one liaud, to make 

 as near an approach to precision as circumstances wiU allow, and on the other 



B 



