ILLUSTRATIONS OF INDIAN BOTANY. 159
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 worth}' 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 locality, where they are equally prevalent. Thus the associates of I. nolitangere, insignis, racemosa and bicolor, might be mutually interchanged ; while the neighbours of I. reticulata, pubertda, &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 engrossing interest, as the success or failure of vast speculations may depend on his acquaintance with, or ignorance of, the external agents which act on the objects of his culture — whether for their benefit or their injury.
Properties and Usrs. Under this head there is little room for remark. One species, Impatiens noli tanpere, which derives its name " Noli tangere" from its acrimony, is said to be so powerfully diuretic that it is capable of producing a diabetes. This I think may be doubted. Applied as a cataplasm on the hypogastrium, it equally acts on the kidneys. Neither this nor, I believe, any other species of the genus is now used in medicine. As however species greatly abound in India the subject, of their medical properties, seems not undeserving of enquiry among those favourably situated for conducting such investigations.
Remarks on Genera and Species. The genera of this order are few, amounting as yet, I believe, to only two, viz. Impatiens and Hi/drocera — the former distinguished by the irregularity, caused by suppression and union of parts of its flowers, the latter, by having them quite regular with a drupacious 5-celled fruit — The species on the other hand, are numerous, and when characterized from dry specimens the most difficult to distinguish, though with recent ones less so than those of many other genera. This arises from the tender succulent nature of the plants causing the flowers, the part from which the best characters are derived, to become so matted together in drying, that it is quite impossible to separate them afterwards in such a manner as to show their forms.
The genus Impatiens affords several excellent marks for the distribution of its species into sectional groups : for example, in some the valves of the capsule roll from the base to the apex ; in others from the apex to the base : this character may serve to divide them into two subgenera — Impatiens and Balsamina. Of Balsamina some species have alternate, others opposite leaves: these differences form the first subdivision of them. Of the alternate leaved section again, so many have ancillary, solitary, one-flowered pedicels ; while others have many flowered peduncles. Of the latter or opposite leaved division, the flowers are either solitary in the axils, or they are fascicled. To these leading divisions several other easily observed subdivisions can be made, which, so vastly facilitate the discrimination of the species, that those of this, generally supposed most difficult genus, become among the easiest to distinguish of those embracing so large a number.
The fullest advantage has been taken these sectional characters, in our account of the genus in the Prodromus as well as in the respective contributions towards the elucidation of its species by both Dr. Arnott and myself, published in Hooker's Companion to the Botanical Magazine, vol. 1st, and in the Madras Journal of Science. To these sources I am under the
