30 FLORA INDICA. 



that the number of known plants is swelled one-third beyond 

 its due extent, by the introduction of bad species founded on 

 habit, and on accidental varieties produced by soil, exposure, 

 etc. This subject admits of classification under two heads, to 

 neither of which can we be expected to devote much space in 

 this Essay. 



1. There are accidental variations due to no apparent 

 causes or to very fluctuating ones, as colour of flowers and 

 leaves, odour, hairiness (to a great degree), development of 

 parts, strength of medicinal or other properties, hardness and 

 various properties of wood, and many others. 2. More per- 

 manent deviations that accompany change of locality, and af- 

 fect more or less all the individuals inhabiting a certain area : 

 these may often be traced to physical causes, and give rise 

 to races and stocks, which are more or less permanent under 

 cultivation and changed conditions, such as habit, hardiness, 

 and duration of life and of foliage (evergreen or deciduous), 

 predilection for certaia soils and exposures, and other cha- 

 racters which are more or less obviously induced by opera- 

 tions that have extended through a series of generations. 



Gregarious plants, in all states, whether wild or cultivated, 

 and field-crops in particular, ofier excellent opportunities of 

 studying these phenomena. Nor are these remarks appli- 

 cable to herbaceous or shrubby plants only : even in this coun- 

 try the variations of the recently introduced Deodar are al- 

 ready attracting attention to the question of its specific diver- 

 sity from the Cedar of Lebanon and that of North Africa*. 



* As regards the specific differences between tlie common Cedar and Deodar, 

 we think the question still open to discussion. We have no fixed opinion on 

 the subject, and in the present incomplete state of our knowledge we recommend 

 caution. The prominent difference strongly urged is founded on error; i.e. 

 that the scales of Cedar-cones are persistent and those of the Deodar deciduous ; 

 the fact being that the Cedars at Kew and elsewhere scatter their cone-scales 

 whenever a warm summer ripens their wood. As to the differences of timber, 

 that of the Cedar is so very variable as to throw suspicion on the value of this 

 character ; and other trees, as we have elsewhere said, present immense difference. 

 The odour and quahty of Cedar-wood varies according to the circumstances 

 under which the trees have been grown. Length and colour of leaf, and habit. 



