Mr Scott Elliot on the Cape Flora. 241 



Notes on the Regional Distribution of the Cape Flora. By 

 G. F. Scott Elliot, M.A. Cantab., B.Sc. Edin. 



(Read 14th November 1889.) 



Mr H. Bolus, in the Cape of Good Hope Handbook, has 

 given a very good division of the flora into five districts. 

 I was able, during a recent visit of some twelve months' dura- 

 tion, to collect plants in all of his divisions; and although, 

 unfortunately, the time 1 spent in each was very short, I 

 noted some interesting points not generally known which 

 may be worth putting on record. 



Mr Bolus' divisions are based on certain definite climatic 

 conditions. There is a range of mountains running inter- 

 ruptedly, and under different names, all round the southern 

 corner of South Africa. These surround the great basin of 

 the Karoo. Now, the predominant winds in South Africa 

 are north-westerly or south-easterly. These mountains 

 intercept the rains, and from the geography of the Continent 

 it follows that the western flanks of the mountains receive 

 their rain mainly from the north-westerly winds, which 

 usually blow during the Cape winter from April to November, 

 while the eastern flanks receive their rain by south-east 

 winds, which blow chiefly during the Cape summer from 

 October to March. Hence, the western and eastern districts 

 have rainfalls, and therefore flowering seasons, at exactly 

 opposite periods of the year,* and form, in consequence, two 

 very natural botanical regions. The Karoo lying within 

 these mountains is characterized by a very low rainfall, and 

 so forms a third very natural region. The two remaining 

 regions are characterized in part by a branch of the tropical 

 flora of Africa which extends down the coast as far as Natal, 

 and in part by a branch of the flora of Central Africa, 

 which forms the northern boundary of the Karoo region.t 



* A very interesting work by Mr D. E. Hutchins, " Cycles of Drought in 

 South Africa," exi)laiiis the difference in rainfall. 



t The rainfall from October to March (inclusively) during the year 1888 

 was : — Cape Town, 4'62 in.; Table Mountaiu, lO'l in. ; Knyrna, 13'47 in. ; 

 Graaff Reinet, 8 '94 in. From April to September inclusively it was: — Cape 

 Town, 31-44 in. ; Table Mountain, 47-8'2 in.; Knyrna, 20-95 in. Graatf 

 Reinet, 7-90 in. 



During June-July, 1888, 13-52 in. fell at Cape Town; 23-44 on Table 

 Mountain ; 3-85 at the Knyrna ; 47 in. at Graatf Reinet ; 89 inches at King 

 AVilliamstown. 



TRAXS. BOT. SOC. VOL. XVIII. 2 G 



