1912-1913-] Notes on Pa rasitic A scomycetes. — III. 3 1 



Rh. salicinum (Pers.) Fr. produces shining black blotches on 

 living leaves of various species of Willow, and Rh. andromedce 

 (Pers.) Fr. on living leaves of Andromeda polifolia. 



Among species usually assigned to JRhytisma, but requiring 

 further investigation, may be noted Rh. empetri B. White, and 

 Rh. urticce (Pers.) Fr. The former occurs on living stems of 

 Crowberry {Empetrum nigrum), and forms a thick, black, 

 smooth, glossy crust : it is locally abundant on the Breadalbane 

 Mountains in Perthshire, and has also occurred on the Largs 

 Hills, Ayrshire. The latter species is not uncommon on dead 

 stems of Nettle (Urtica dioica), on which it forms a thin, 

 shining, black crust. 



Another parasite belonging to this group is Cryptomyces 

 aureus (Sow.) Mass., which forms large, black, blister-like 

 patches on living branches of Willow. The margin of the 

 patch is -well defined, and is frequently lobed. At maturity 

 the black surface becomes cracked so as to expose the disk, 

 and often falls away. The ascophores are immersed in a 

 white stroma covered by the blackened epidermis ; and the 

 asci contain eight hyaline, elliptical, continuous spores. This 

 species was known to Greville, and was described by him in 

 the ' Scottish Cryptogamic Flora ' under the name of Crypto- 

 myces Wauchii. 



The parasitic species of the genus Pseudopeziza may be said 

 to form a connecting link between the two types of Discomy- 

 cetes represented by Phacidium and Peziza respectively. This 

 relation is best seen in Ps. trifolii (Bern.) Fckl., formerly 

 assigned to the genus Phacidium. It occurs abundantly on 

 living leaves of various species of clover, especially Trifolium 

 repens, and produces dark spots, on the surface of which are 

 developed one or more minute, yellowish, pustular discs or 

 cups. These burst through the epiderm, which usually forms 

 a toothed fringe surrounding each cup. Other parasitic 

 species of this genus, tending more or less towards the 

 pezizseform or cup-like type of ascophore, are Ps. ranunculi 

 (Wallr.) Fckl., which produces blackish cups on the under 

 surface of conspicuous dark-brown spots on leaves of Creeping 

 Buttercup {Ranunculus repens) ; Ps. repanda (Fr.) Karst., on 

 various species of Ritbiacem, especially Sherardia arvensis and 

 Galium saxatile ; Ps. cerastiorum (Wallr.) Fckl., on Cerastium 



