INTRODUCTION. 79 
The climate is temperate; the mean annual temperature 61° F. ; 
frosts on the low ground are rare, and even on the mountain-tops snow 
is an unusual occurrence and never lies for more than a few hours. 
The average annual rainfall varies in different localities from 23 to 
about 60 inches, and two-thirds of it fall during the winter months of 
May, June, July, and August; the warmth of the summer months 
being tempered by the prevalent southerly winds of that season. In 
many respects the climate resembles that of the Riviera. 
The steep ravines of the mountains are filled with indigenous 
shrubs or trees, while their sides are in many places dotted with the 
silver-tree (Leucadendron argenteum) ; at their feet are scattered bushes 
or copses of imported pines and oak; all else, including the sandy 
downs of the isthmus, is covered with a heath-like growth of small 
dull-coloured shrublets, from one to three feet in height, yet not closely, 
but interspersed with a great variety of herbs, Restiacex, grasses, and 
bulbous plants. Stretches of grasses, or grass-like plants, occur in a 
few places where the bushes by continued burning and grazing have 
been eradicated, but are not common. Surface-water, except for a few 
months of the rainy season, is deficient, and aquatic plants, though not 
absolutely wanting, are not abundant either in species or individuals. 
IJI.—Orcuips In RELATION TO THE FLORA OF THE PENINSULA. 
The Flora of the Peninsula, so far as yet known, consists of about 
1750 species of flowering plants. It will thus be seen that the Order 
OrcuDE® (of which 102 species are enumerated in this book) occupy, 
for a Flora of the temperate zone, an extremely high position, viz., 
fourth (after Composirm, Lecuminosm, and Ericacez), and actually 
constituting 5°8 per cent. of the whole. 
The Cape Peninsula forms a portion of the great South-western 
Region of the Cape, the Flora of which is so remarkably different from 
that of any other part of Africa, and presents so many striking 
affinities with that of Southern, and especially South-western, Australia. 
The Orcuipe®, however, assume a much higher position in respect of 
number of species, in the Peninsula, than they do in the S.W. Region 
of the Cape as a whole, the Order only ranking tenth in number in the 
latter. There is little doubt that they here reach their maximum for 
South Africa, and are probably even more numerous than in any area 
of equal extent on the whole continent. 
As the floral affinity of this Region with Australia has been referred 
to, it must be added that in respect of the Orcumem of both countries 
scarcely any relationship is to be traced, and that on the contrary the 
divergences are considerable. In Australia the tribes Vander and 
Neottiex chiefly prevail (Ophrydex being restricted to two species) ; 
while on the Cape Peninsula the Vande are few (six species), the 
