GYMNOSPORANGI UM. 



391 



},,• 



•iiidia, 



Roestelia (?), - 



(?) - - 



pjcnidia, 



Rostelia cornuta, - 

 R. penicillata, 

 R. penicillata, 

 R. penicillata, 

 spots, - 

 thick spots, - 

 pycniclia ami aecitlia, 

 thick spots, - 

 pyciiidia and aecidia, 

 pycnidia only, 

 pycnidia and awidia, 



Plowiigl 

 Thaxter. 



Haitig. 

 Nawaschin. 



Pevritsch 



Gymnos23orangium juniperinum L. and G. trcmclloides Hart, from 

 twigs and needles of Juniperus comiminis produced : 



On Host-plant. Spore-form. Authority. 



Pyrus (Sorbus) Aiccuparia, - - Rostelia cornuta, - - Tubeuf. 

 Aroma rotundifolia, - - - short aecidia, - - Rathay. 



Pyrus Mains, - - - - 

 Pyrus {Sorb lis) Aria, 

 Cydonia vtdgaris, . . . . 

 Pyrus {Sorbus) Aucuparia, 

 Pyrus Malm, - - - - . 

 Amelanchier canadensis, - 

 Pyrus {Sorbus) Aria, 



Pyrus Mains, 



Pyrus {Sorbus) Chumaemespilus, 



Mespilus macrocarpa, 



Pyrus communis, - . - . 



Pyrus {Sorbus) Aria, 



Pyrus {Sorbus) Aria x Chamaemesp., 



Pyrus Malus, 



Pyrus {Sorbus) Chumaemespilus, 



Pyrus {Sorbus) A ucuparia, 



Aronia rotundifolia, . . . ,, ^, 



Pyrus {Sorbus) torminalis, - - pytiiidia and spots only, 



Crataegus Pyracantha, . . - ,, ,, 



Cydonia vulgaris, - - - - „ ,, 



Pyrus Mahis, --'.-- Rostelia peniciWita, 



Formation of p}X'nidial spermogonia always 

 of aecidia. 



This fungus is of practical import on account of its occurrence 

 on leaves of apple-trees. Its attacks may be very virulent 

 and widely distributed. Eriksson mentions that near Stockholm 

 it is common on apples, and so virulent that many trees have 

 every leaf studded with Roestelia. (American apple-trees suffer 

 from Roestelia pirata, the aecidia of Gijmnosporangium macropvs 

 and other species. ■ See p. 402.) 



Gymnosporangium juniperinum (L.) {G. conicnm Hedw.) 

 (Britain and I'.S. Aniorica). This species, also frequenting 

 Jtinijjeri/s eommunis, is distinguished by its shorter spores, 

 which, as Dietel pointed out,^ have a colourless papilla over 

 each germ-pore. The teleutospores are found on both twigs 

 and needles, on the former, however, they are much smaller 



'^ Forstdch-natnrwiss. Zeitsrhrift, 1895, p. 378. 



- Rostinp. 



precedes that 



