Ixxvi SPECIMEN, &c. 



ceive, constitute an appropriate appendage to a Flora of 

 Oxfordshire, but its insertion would be more likely to mislead, 

 than to inform, until the geological habitats of the plants 

 therein enumerated had undergone a more thorough revision, 

 than has as yet been accomplished. 



The specimen, therefore, now given of the Index in question, 

 is intended merely to convey such an idea of its construction, 

 as may enable Oxford Botanists, if they please, to co-operate 

 with myself, and with each other, in collecting the data neces- 

 sary for perfecting the design, so far as this county is concerned ; 

 and likewise to engage others in distant parts of Great 

 Britain to draw up Indexes of a similar description to Floras 

 of their own neighbourhood, and thus to realize the views of 

 the Association by acting on one uniform plan. 



The utility of such an Index with reference to the Oxford 

 Botanist, is chiefly that of enabling him to perceive at a glance, 

 in what particular soil and situation each plant is here met 

 with, serving, therefore, to abridge the labour of reference, 

 and to keep alive in liis recollection the important fact, that 

 a certain, though as yet an imperfectly understood influence 

 is exerted upon plants, by the combined agency of the soil, 

 the air, and the temperature. 



But a collection of such Indexes, which should embrace 

 the whole or the greater part of Great Britain, would, as 

 is observed in the Report, serve a more important purpose, 

 by supplying us with the data requisite for determining, what 

 kind of relation may subsist between particular plants, and 

 certain kinds of soil or situation. 



In enumerating the different Stations in which the plants of 

 Oxfordshire are found, I have adopted the classification given 

 by M. Decandolle in his admirable Essay on the Geography 

 of Plants, which is inserted in the eighteenth volume of the 

 Dictionnaire d'Histoire Naturelle. The Stations, of which 

 Oxfordshire affords any examples, will, according to this 

 method of arrangement, be nine in number, and though (as 

 Professor Lindley observes in his Introduction to Botany) 

 some of them are rather vague and uncertain of application, 

 yet they seem to comprise the most remarkable differences of 

 station, and, therefore, desenve to be attentively noted. 



