74 REPORT—1846. 
ZOOLOGY AND BOTANY. 
General Observations on the Geographical Distribution of the Flora of India, 
with Remarks on the Vegetation of its Lakes*. By Prof. Royie, M.D. 
Tue author stated, that though the plains of India were generally considered to 
support only tropical vegetation, yet this differed very much both in the different 
parts of the country and at different seasons of the year. The plains, moreover, 
might be distinguished into moist and dry; in the former, embankments were re- 
quired to prevent inundation ; and in the latter, canals for irrigation. In the rainy 
season, however, most parts supported a tropical vegetation, and rice could be suc- 
cessfully cultivated. So in particular localities, covered with primeval forests, some 
tropical plants extended even to some of the hot valleys in the neighbourhood of 
Cashmere. In the cold weather, however, that is in the winter season, some Euro- 
pean plants make their appearance in the plains, especially of North-west India ; 
and wheat and barley are as successfully cultivated as in Europe. So in ascending 
its mountains, especially the Himalayas, every variety of vegetation is met with, 
almost as much as in proceeding from the equator to the poles, being perfectly tropical 
at the base, European on the ascent, and polar at the summits of its lofty peaks. 
The mountains however are also under the influence of the rainy season, and are, 
indeed, fora great part of the season covered with a canopy of clouds in consequence 
of the air heated and loaded with moisture in the valleys rising to an elevation 
where the temperature is below the point of deposition or dew-point. Considerable 
uniformity of temperature and moisture is produced, in consequence of there being 
little cooling at night and but little heating during the day, from the sun being 
unable to penetrate the cloudy canopy, and we therefore see some of the Balsams, 
Scitamineze and Orchidez flourishing at elevations where they could not exist for a 
day during the dry heat of summer or the piercing cold of winter. 
In so extensive a territory and diversified a climate there is necessarily a numerous 
and a varied flora, The-known species of the Indian flora are about 10,000 in 
number, the majority of course characteristic species, but on the Himalaya of an 
European type. The vegetation of the different parts of the Indian empire bears a 
resemblance to that of different countries where there is a similarity of climate, and 
about 250 species which are found in the plains and mountains of India, also occur 
in other, some of them very distant parts of the world. The vegetation of different 
tropical countries is very similar, and they are subjected to the influence of the same 
physical states. The affinity is very perceptible between the botany of the southern 
parts of India and that of the Indian Archipelago; the same thing occurs with the 
flora of southern China ; this therefore resembles that of southern India, Mr. Brown 
long since remarked that about 200 species of the Australian flora are also found in 
the islands of the southern Pacific as well as in India. Dr. Jack cbserved at Sin- 
gapore many remarkable points of coincidence between its productions and those of 
continentai and western India on one hand, and the islands of the Eastern Ar- 
chipelago on the other; while the prevalence of some Epacridez. connected it with 
that of New Holland. The botany of a great part of the drier parts of India has 
a great resemblance to that of the west coast of Africa, as originally remarked by 
Mr. Brown, who ascertained that there were about 40 species common to those 
distant regions. Dr. Royle in the same way remarks a correspondence between the 
flora of Egypt and that of the drier parts of northern India, and also that some of 
the characteristic forms of the Mediterranean flora approach its north-western 
frontier. 
The Himalaya mountains have a tropical vegetation at their base and in their 
valleys. At elevations of 6000 and 7000 feet, the climate is temperate, and the flora 
corresponds with that of European regions and of the Caucasus, both in its arboreous 
and herbaceous vegetation, and in the prevalence of many of the same species which 
are found here in our fields. Among them also are several genera, which, until the 
last few years, were thought to be peculiar to China, and others to North America. 
* This communication was made to the Association at Cambridge in 1845, and was acci- 
dentally omitted in the Report for that year. 
