Rhodesian species of Fuirena , Hesperantha , and Justicia . 203 
position, the caiiline leaves showing a very- 
considerable increase in size, though still linear 
in outline (Text-fig. 10). The whole shoot at 
this stage assumes a dorsiventral habit, the 
little axillary flowering shoots rising erect 
from each node. It is the remains of these 
decumbent flowering shoots which form the 
radiating dead branches in Text-fig. 8 , d.b., 
in which no trace of nodal rooting was ob- 
served either in the field or in the material 
brought back. The cauline leaves also in 
this case, though they increase so consider- 
ably in size, remain more linear than the 
ovate leaves on the purely vegetative shoot, on 
which there are no flowering axes to exhaust 
vitality. The later development of vigorous 
vegetative shoots brings this highly specialized 
Justicia into line with the general charac- 
teristic type of vegetative activity already 
referred to, by which plants requiring a long 
period of development economize their re- 
sources by taking the process in two stages. 
This habit is possibly stimulated in her- 
baceous plants by the annual veld fires, as it 
ensures a double chance in case of premature 
destruction of the purely reproductive shoots. 
That it forms the direct response to the 
prevailing climatic and edaphic conditions is 
shown by the wide adoption of the principle, 
in one form or another emphasized in the very 
early flowering of nearly all the trees, many 
shrubs, and those herbaceous plants and bulbs 
the organization of which calls for a large 
area of assimilating surface to elaborate next 
years supplies. The decumbent shoots also 
form a very general adaptation, in this case 
peculiarly appropriate, for retarding evapo- 
ration, and ensuring a shade area at the stage 
when the winter buds are being laid down 
on the rhizome. 
In its peculiar complexity of organiza- 
tion Justicia eiegantuia not only occupies 
an isolated position in its own genus, but 
Fig. 10. Justicia eiegantuia. 
