Bio-histological notes on some new Rhodesian 
species of Fuirena, Hesperantha, and Justicia. 
BY 
L. S. GIBBS, F.L.S. 
With Plates XI and XII and ten Figures in the Text 
I N a former paper 1 some points of biological interest in connexion with 
the above plants collected by the author in Southern Rhodesia were 
briefly touched upon. The results of further investigation are now given in 
greater detail, and show very marked adaptation to physiological conditions, 
which in the case of Fuirena Oedipus and Justicia elegantula have resulted 
in types of peculiar specialization quite outside the known limits of their 
respective families. 
On the high Matabeleland plateau of Southern Rhodesia the rainfall 
varies from 17 to 30 inches, occurring chiefly in the form of thundershowers, 
and it is entirely limited to the summer or hottest months of the year, when 
evaporation is greatest. The general altitude is 3,000-4,500 feet, with 
a mean annual temperature of 65° to 70° and five absolutely rainless months 
in the year. In a tropical country of this description the rainfall is sufficient 
to support a stunted growth of trees, many shrubs, and herbaceous plants. 
These meet the extreme conditions to which they are exposed rather by 
husbanding the general underground water supply in the soil than by 
elaborating individual forms of water reservoirs. Water storage tissue 
seems more characteristic of regions of slight intermittent rain and short 
periods of surface moisture. 
The long seasonal winter drought, with cold nights and hot days, is 
met, in the case of trees, by the throwing off of leaves and by a great variety 
of cork protection. The efficiency of this enforced quiescence is proved by 
the fact that the severe frosts which sometimes occur at this season leave 
the native vegetation untouched, though they are often injurious to intro- 
duced trees and shrubs. 
Herbaceous plants have evolved most massive underground root 
systems, and if they do not die down every year they are cut back by the 
veld fires. The aerial parts are characterized either by a flat spreading habit 
1 Gibbs, A Contribution to the Botany of Southern Rhodesia. (Joum. Linn. Soc., xxxvii, 
1906, pp. 426-94, Pis. XVII-XX.) 
[Annals of Botany, Vol. XXII. No. LXXXVI. April, 1908.] 
