38 FARM WEEDS OF CANADA 



ERGOT on COUCH, RYE and TIMOTHY 



{Claviceps purpurea (Fr.) Tul.) 



There are often found among grains of rye, rarely among 

 those of wheat, and abundantly among the seeds of some grasses, 

 blackish or purplish solid bodies, commonly called ergot. Fresh 

 specimens are of a waxy or oily consistency, purplish white 

 inside. They are the storage organs or resting stage of a parasitic 

 fungus belonging to the genus Claviceps. Ergot grains vary in 

 size and form, according to the species of grain or other grasses 

 on which they develop. Each of these solid bodies is called a 

 sclerotium (plural sclerotia), derived from a Greek word skleros, 

 hard or dry, in allusion to their nature. They are a part of 

 the vegetative system, the "spawn" of the fungus, in a resting 

 condition, but capable of growth in the spring under such favour- 

 able conditions of warmth and moisture as they get when sown 

 with crop seed, or when lying on the ground at the bases of the 

 stems on which they were formed the previous summer. In the 

 spring small toadstool-like bodies, on violet stalks, with round, 

 orange-coloured heads, about the size of mustard seed, are pro- 

 duced from the sclerotia lying on the ground. These develop 

 enormous numbers of microscopically small spores (organs 

 analogous to the seeds of higher plants), at the time when grasses 

 and grains are in flower. The minute spores, carried by currents 

 of air or by insects, lodge in the flowers of the grasses and grow; 

 in a short time they completely destroy the seed and form from 

 them the horn-like sclerotia. During the summer spores are 

 formed on these horns; at the same time appears a sugary 

 secretion, very attractive to insects, which carry off on their bodies 

 many of the summer spores to the flowering heads of other grasses 

 and thus spread the infection. Late in the summer the pro- 

 duction of spores stops, and the sclerotia or storage organs 

 begin to lay up a kind of starch found only in fungi and known 

 as fungus starch, as well as oils, to serve as fopd for the growth 



