BRITISH CENTRAL AFRICA 
218 
that tint. Still the grass of Central Africa is one of its great plagues. Between 
the months of November and February there grows up a monstrous herbage 
under the influence of the sun and 
rain. The grass stems will sometimes 
reach eight feet in height. Not only do 
many of their leaves cut like razors or 
stab like spears but in the autumn months 
of April and May their seeds ripen and 
in some cases seek distribution by methods 
painful to the human animal. There is 
one especially—a species of Stipa, whose 
seeds I here illustrate. As you pass along 
a native path which is almost invisible 
(for grass growing on either side leaves 
nothing but an obscure narrow tunnel), 
the seeds of this Stipa easily detach 
themselves and descend with a spiral 
flight on to your person, the slight im¬ 
petus of their fall carrying the sharp 
barbed point of the seed right into the 
clothing ; here the movement of the body 
acting oh the barbs of the seed works it 
farther and farther in, so that it eventually reaches and scratches the skin. There 
are cases reported of this Stipa where the seed has actually penetrated the skin 
of certain animals. At one time the idea was mooted that the seed germinated 
thus in the flesh, but this is not true. It is a mere accident that the barbed 
PAPYRUS 
FOUND ON ALL STAGNANT WATER IN TROPICAL 
Africa ( Pistia stratiotes) 
