1837.] 



On the Genus Impatiens. 



5 



season of their greatest perfection, not exceeding 70°, if so much. At 

 Shevagerry, about fifty miles north of Courtallum, I found five, out of 

 seven species, on the highest tops of the mountains ; none of the five 

 under 4,000 feet, and three of them above 4,500 feet of elevation ; the mean 

 temperature, as deduced from twenty observations, continued through 

 four days, at an elevation of 4,100feet,being 65o of Fahrenheit's scale. The 

 two found at a lower elevation, were both either growing in the gravelly 

 beds of streams, or immediately on their banks ; the temperature of 

 which was ascertained to be 65<>, while that of the air at noon was only 

 about 75°, a temperature, I presume, but little above that in which they 

 delight on the Bengal frontiers. There is one other point, respecting 

 the effect of climate on plants of this genus, to which I wish to call 

 attention, as it may ultimately prove useful to any one who may again 

 attempt to subdivide it, and is, in the mean time, in a physiological 

 point of view, exceedingly curious. It is, that most of the species 

 from the colder regions of the Himalaya mountains, correspond with 

 the European I. noli tangere, in the form and dehiscence of their cap- 

 sule, that is, they split from the base, rolling the segments towards the 

 apex, while those of the warmer regions split from the apex and roll 

 their segments towards the base. This difference of habit between 

 those of India proper and the Himalayan forms, is well worthy of 

 notice, as it shows, that the affinity which exists between the flora of 

 the latter and that of Europe, is stronger than between it and the Indian, 

 and extends to even this most purely tropical genus. 



The innate power which plants enjoy of selecting the soil and climate 

 in different countries, however remote, most suitable to their perfect 

 development, and which the preceding remarks have shown to be so 

 eminently possessed by those of this order, may, when the subject has 

 been more studied and is better understood, prove of immense benefit 

 to the scientific cultivator. 



Taking for an example the genus Impatiens, we may at once infer, 

 that herbaceous plants growing where its species abounds, and arriving 

 at maturity about the same time, may be transferred to any other loca- 

 lity, where they are equally prevalent. Thus the associates of I. noli- 

 tangere, insignis, racemosa and bicolor, might be mutually interchang- 

 ed ; while the neighbours of I. reticulata, puberula, &c. might be made 

 to change places with those of I. fasciculata, grandis, and many more, 

 •with every prospect of success. The limits to which this rule may 

 be extended are as yet totally unknown, and cannot be estimated, until 

 plants are studied not as insulated individuals, but in connexion with 

 the soil, climate, aspect, exposure, &c. in which they are observed to 

 arrive at the greatest perfection. This is a study which the scientific 

 botanist pursues in its relations to the physiological peculiarities of 

 plants, but to the cultivator, it becomes one of much deeper and more 



