208 FUNGOID PESTS OF CULTIVATED PLANTS. 



Not less than eighty species of fungus parasites have been recorded as 

 occurring on various species of Quercus, at home and abroad, but not 

 many of them are British. 



OAK-LEAF RUST. 

 Uredo Quercus (Brond), PL XX. fig. 18. 



This parasite occurs, but not commonly, on the under side of the 

 leaves of young Oak saplings when about three or four feet high, but 

 probably without inflicting any serious injury. Nothing is known of any 

 other stage than that of the uredospores. 



The pustules are rounded and small, and either scattered or in clusters, 

 yellow at first, and afterwards approaching orange. The uredospores are 

 nearly globose, rough externally, and orange-yellow (15-25 x 12-15 n). 



It has been assumed, rather prematurely, that this is an early con- 

 dition of some species of Melampsora. 



Known also in France, Belgium, Germany, Switzerland, and Italy. 



Sacc. Syll. vii. 2126 ; Plowr. Brit. Ured. 257 ; Cooke, Hdbk. No. 1573 ; 

 Cooke, M.F. p. 216. 



Seedling Oaks are liable to the attacks of a fungus at the roots, which 

 develops into a disease resembling the white root-rot, and in its mature 

 condition is known as Rosellinia quercina (Hart.). 



Hart. & Som. Dis. Trees, p. 78, figs. 26-28 ; Mass. PL Dis. p. 121. 



VEGETABLE BEEF STEAK. 

 Fistulina hepatica (Fr.). 



This well-known fungus is often to be seen flourishing year after year 

 upon the same living Oak tree, and is gathered promptly, on account of 

 its esculent properties. It is somewhat variable in form, being rounded, 

 semicircular, tongue- shaped, and often two or three together, liver-coloured, 

 not unlike a piece of bullock's liver, soft and easily cut, and internally 

 mottled somewhat after the manner of Beetroot, and juicy, with a rather 

 acid taste. The under surface is a little convex and paler, perforated with 

 innumerable pin-holes which are mouths of tubes, closely packed side by 

 side, bearing the spores on the inner surface. These spores are salmon- 

 coloured and nearly round. Sometimes specimens have been found 

 attaining a weight of thirty pounds, but usually only three or four 

 pounds. 



It is doubtful to what extent this fungus is a cause of injury to Oaks, 

 as it is always found on dead parts. 



Found throughout Europe, in North America, Australia, and Northern 

 India. 



Sacc. Syll. vi. 4849 ; Cooke, Hdbk. No. 841 ; Soiv. B.F. t. 58 ; Grev. 

 Sc. Crypt. Fl. t. 270 ; Mass. Fun. Fl. i. p. 256, figs. 8-10. 



SULPHURY WOOD-HOT. 



Polyporus sulfureus (Fries). 



This large and attractive-looking pplypor is a wound parasite on 

 several trees, such as Oak, Alder, Willow, Poplar, and even Pear and 



