334 



i:\lHiNIVLLUM 



Teleutospores. Sori hypophyllous or occasionally epiphyllous, 

 more or less covering the whole surface, crowded, aecidium-like, 

 sunk in tlif leaf-tissue which is slightly swollen, surrounded by 

 a thin peridium in the shape of a shallow cup, with a short, 



Fig. 251. E. Euphorbiae-silvaticae. a, affected leaf of E. amygdaloid.es, 



nat. size; b, aecidio-teleutospore ; c, germinating spore; d, another, not 

 so advanced, x 540 ; e, inner, and /, outer wall of peridium-cell, x GOO. 



torn, slightly revolute margin; spores in evident chains, bluntly 

 polygonal or subglobose, densely but finely verruculose, orange, 

 18 — 23/t; epispore about 1/x thick; basidiosp' »res i >bovate, yellow. 



On Euphorbia amygdaloides (= E. silvatica). Rather un- 

 common. April — June. (Fig. 251.) 



The mycelium usually perennates in the plant. The affected shoots 

 are taller than the normal ones, with shorter, wider and paler leaves; 

 they seldom flower. This species externally closely resembles an tecidiuru, 

 and can be distinguished from one only by the different mode of germina- 

 tion of the spores. The secidia which occur on other species of Euphorbia 

 belong to different life-cycles, Uromya s Pisi etc. 



The peridium of this species is more strongly developed than that of 

 the following one ; its cells are densely warted, and arranged in distinct 

 rows. A long account of the behaviour of the parasite is given by 

 Plowright (I.e.). The spores germinate readily in the summer as soon 

 as produced. 



Distribution : Europe. 



