Rhodesia and the Victoria Falls. 
93 
In the other more median section the lowest whorl is repre¬ 
sented hy fragments of two sporangia, and in one of these a few 
large spores are accompanied on one side by a large number of 
abortive spores. These large spores, like the sporangium containing 
them, have not been well-preserved, but the only one of them which 
allows of satisfactory measurement has a diameter of about 135//. 
Of the other sporangia, most have spores of the normal dimensions, 
but in one or two a few abortive spores occur, and the survivors 
are larger than the normal. 
It is interesting to note that the sporangia containing the larger 
spores occur at, or near, the base of the strobilus, just as is the 
case where advanced heterospory is found. 
In comparison with Calamostachys, abortion has proceeded a 
step further than in C. Binneyaua, but not so far as in C. Casheana. 
If one imagines the spores produced in tetrads, not merely some of 
the spores in the tetrad, but whole tetrads, have aborted, with a 
corresponding increase in the size of the survivors, in the extreme 
case to about one-and-a-half times the normal diameter. 
SKETCHES OF VEGETATION AT HOME 
AND ABROAD. 
II.— Some Aspects of the Vegetation of South Africa. 
By F. E. Weiss, D.Sc. 
Part III.— Rhodesia and the Victoria Falls. 
1HE passage through Bechuanaland and the visit to Rhodesia 
coincided, as our stay in the Transvaal had done, with the dry 
season, so that the country had a very arid and parched appearance. 
The land traversed during the first part of the journey through 
Khama’s country was flat and practically a grass steppe, though 
northwards trees became more numerous and the aspect more like 
that of a savannah, in parts quite park-like. The trees were largely 
Leguminosae, many of them being acacias, some of which were 
just coming out into flower, often on quite leafless branches. 
