that his collection contains several not in Wallich’s list, and Mr. Arnott writes me that he has
recently described sixteen new ones from Ceylon. To these last, my excursions on the Cour-
tallum and Shevagerry hills have added about as many more. Of the Courtallum ones, those
only of which drawings were made, are introduced into this paper; not having, either specimens
or sufficiently perfect notes, to enable me to define the rest.
It is a curious, and to me an inexplicable fact, that a genus so strikingly Indian, and associating
such a host of species, should have been so little known to Roxburgh. He only describes
three in his Flora, though I am sure I speak within bounds, when I assert that the coun-
tries, whence he derived the materials for his work, will be found to present an assemblage of
not fewer than one hundred species. It is no doubt an eminently alpine genus, delighting in a
cool and moist climate; hence it is-unknown on the plains of Coromandel, though not unfrequent
in Mysore, but, so far as I have seen, only abounding, in the Peninsula, on the higher hills
participating in the western monsoon, which enjoy, during the hot months, a moderate range of
temperature, with a very humid atmosphere. Some, (how many is not yet known,) are found
during the monsoon on the Malabar coast, little elevated above the level of the sea, but, except
in Tanjore, I have riot seen one of the order on the plains eastward of the ghauts, beyond the
influence of that monsoon: and the only one found there, is Hydrocera trijiora, which grows,
but is not common, in its ditches and swampy grounds, during the cool season, and is the only
place where I have yet seen it.
This peculiarity of distribution may account for his not having met with Peninsular spe-
cies, as he was but little in the southern provinces, and perhaps they are not found in the eastern
range of the northern ghauts : but, twenty-two of the forty-seven species named by Wallich,
are from Silhet, Pundooa and Nepaul, from all of which plaees Roxburgh procured plants, and
one of the three he^describes is from Silhet. A moist climate and moderate temperature are
the circumstances most favourable, if not indispensable, to their production ; hence we find
twenty two, of the remaining twenty-five species named by Wallich, natives of the Peninsula,
but confined to the ghauts and Mysore where these contingencies meet. This fact was first
noticed by Mr. Royle, who, after remarking the nearly equal division of the forty-seven species
between the frontier mountains of Bengal and the Peninsula, adds, “ a singular equality of
numbers, seeing that we have hitherto found Peninsular and South of India genera confined to
the base of the mountains, and if found existing on them, generally only as single species; but
here we have them in equal numbers, some of them extending to an elevation of seven thousand
feet.
li This anomaly can only be explained, and a stronger fact cannot be adduced in its confirmation,
than that the moisture and moderate temperature of the rainy season in the hills
(for it is at this season only that they are found) is as favourable to their growth as the heat and
moisture of the Peninsula. I have never met with any in the plains of India; but have heard
from travellers that they are abundant in Central India, whence we may expect some new species,
as well as from the Neilgherries.”
The facts which I have mentioned regarding the distribution of the Peninsular species, go
to prove, that heat and moisture are not the circumstances most favourable to their production
here, but moisture combined with a moderate but equal temperature. At Courtallum for example,
whence I have eleven or twelve species, they most abound in shady places on the tops of
the hills, with a mean temperature during the season of their greatest perfection, not exceeding
70°, if so much. At Shevagerry, about fifty miles north of Courtallum, 1 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 4,100 feet, being 65® 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 capsule, that is, they split from the base, roiling the segments towards
the apex, while those of the warmer regions split from the apex and roll their segments towards
the base. 1 his 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 sho,wn 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 Tmpatiens,, 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. noli-
tdnghre, insignis, racemosa and bicolor, might be mutually interchanged; 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 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.
P roperties and Uses. Under this head there is little room for remark. One species,
Impatiens noli tangere, which derives its. name “ JYoli "tangere” from its acrimony, is said to
be so powerfully diuretic that it is capable of producing a diabetes. This I think may be
doubte,d. Applied as a cataplasm on the hypogastrium, it equally acts on the kidneys. Neither
this nor, I belipve, any other.species of the geniis is ndvwused 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.
R emarks on G enera and Species. The genera of this order are few; amounting as yet,
I Relieve, to only two, wi... Impatiens and Hydrocera—the former distinguished by the irre-
'gulanty, caused by suppression and union of parts of its.flowers, the, latter, by having them
quite regular with a drupacibus 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 leas 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 axillary, 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 geniis, 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. [st, and in the Madras Journal o f Science. To these sources I am under the