INJURIES INDUCED BY PLANTS 



161 



MELAMPSORA (CALYPTOSPORA) GOEPPERTTANA l 



The fungus which attacks the 

 cowberry, and its secidium form, 

 sEcidium columnare, which pro- 

 duces the columnar rust of the 

 silver fir, are indigenous wher- 

 ever silver firs abound. The 

 first-mentioned form, indeed, is 

 also met with in districts from 

 which the silver fir is absent, and 

 this furnishes a proof that the 

 aecidium form possesses only a 

 facultative character. 



Specimens of V actinium Vitis 

 Idcea that are attacked by the 

 parasite are at once distinguishable 

 from healthy plants by their man- 

 ner and habit of growth. Whereas 

 the latter rise but a short distance 

 above the ground, individuals that 

 are infested by the fungus grow 

 quite erect, display an unusually 

 vigorous height-growth, and de- 

 velop two shoots even in the same 

 year. The diseased plants, singly or 

 in groups, tower above the healthy 

 plants, whose height they exceed 

 in some cases by a foot. At the 

 same time they exhibit a striking 

 appearance, the greater part of the 

 stem being swollen to the thickness 

 of a quill, while only the upper 

 part of each shoot retains its normal 

 dimensions (Fig. 91). At first the 

 thickened spongy part of the stem 

 is of a white or beautifully rosy 

 red colour, which soon, however, 

 changes into brown, and later be- 

 1 Hartig, Lehrbuch der Baumkrankheiten, ist edition, pp. 56 etseq., Table II. 



M 



FIG. 91. A plant of V. Vitis Idcea 

 which has been infected by M. 

 Goeppertiana. a, the infected 

 stem containing the mycelium. 

 The new shoots b, in the year 

 succeeding that in which the plant 

 was infected, undergo abnor- 

 mal thickening under the in- 

 fluence of the mycelium ; the 

 apex alone retaining normal 

 dimensions. c, the youngest 

 shoot ; rf, a dead portion. 



