CHAPTER I 
LIFE-HISTORY OF PUCCINIA CARICIS, THE NETTLE 
AND SEDGE RUST 
Puccinia Caricis has two of its stages, the spermogonial and 
ecidial, on the Nettle (Urtica dioica and other species), and 
two others, the uredo- and teleutospore-stages, on various species 
of Carex, especially C. paludesa. The first appearance on the 
nettle is in the spring, about the end of April or the beginning 
of May, when small swollen yellowish spots can be seen on the 
upper surface of the nettle-leaves. These spots are round and 
convex above, sunken beneath, and about 3—4 mm. in diameter ; 
soon they turn orange on the upper surface, owing to the 
development thereon of the spermogones, small flagon-shaped 
bodies walled in by a large number of slender orange hyphe 
and filled with many hundreds of minute spore-like cells, the 
spermatia, which are orange in mass, though singly they appear 
colourless (Fig. 1). 
Fig. 1. P. Caricis. Section of leaf of Nettle, showing the hypertrophy 
produced by the mycelium of the ecidium-stage; a spermogone, on 
the upper side of the leaf, and two ecidia, one closed, on the under 
side. The upper face of the leaf is turned downwards. x 60. 
G. U. 1 
