311 
south-east. But perfectly glabrous nodes—glabrous from the 
ee ae es gr 
are two or more spikelets in a fascicle, the tendency is towards a 
reduction of the sexual organs in the outer spikelets, so that their 
upper floret becomes male and the lower neuter or, in extreme cases, 
both are neuter, This reduction may or may not be accompanied 
by a slight increase in length and nervation of the valve of the 
lower floret and sometimes also of the upper glume. Those fluctua- 
tions are generally found within the same inflorescence, the lower 
Considering the instability of all these characters it is clear that 
the discrimination of subordinate groups other than sports or 
mutations within P, purpureum in so far as it is based on them 
must result in the production of artificial divisions and can serve no 
useful purpose, I refrain therefore from subdividing the species or 
taking up Hackel’s varieties sambesiense, nudum and ternatum,” an 
even doubt whether Leeke’s species P. flavicomum, P. pruinosum 
and P, pallescenst can be maintained, as all the distinctive characters 
which he adduces seem to come within the limits of fluctuation just 
described. Unfortunately Leeke omitted to quote the specimens 
on which he bases his species, nor does he give any indication of 
their habitats except in the most general terms, as Hast Africa or 
Togo ; but so far as they go, the species cited occur entirely within 
the area of P. purpureum. 
* In Schinz, Plantae Menyharthyanae in Denkschr. Ak. Wiss. Wien, 
1. Ixxviii, p. 400. 
vy Leeke, Abstamm. u. Heimat. d. Negethirse, pp. 45-47. 
25633 A 2 
