Arthur and Kern; Peridermium 



411 



Spores coarsely verru- 



cosa 



Branch abruptly swollen into a 



gall. 



Taeda ) 

 falustris) 



12. P. fusiforme. 



Gall globoid, lobed and C P. patula 



irregular. 



Strobus : 



P. oocarpa 

 P. rigida 

 P. virginiana 

 Gall globoid, outline regu- I P. echinata 

 lar. \P. Taeda 



P. divaricate 



P. ponderosa 



13. P. mexicanum 



1 4. P. Cerebrum. 



Caulicolous 



Picea : 



Branch abruptly swollen into a 



gall. 

 Gall globoid, outline regular. {S. Strobus 



15. P. globosum. 



Foliicolous. 



Mycelium perennial, forming 



witches' brooms. 



Leaves somewhat adherent. 



Leaves fugaci 



P. Parry an a | 

 P. Engelmanni) 

 Mariana 



16. P. boreale. 



Mycelium annual, not forming 



witches' brooms. 

 Pycnia con-picuous. 



Aeciospores small. 



(P. Mori 



\P. Enge, 



Engelmanni 



17. P. color a dense 



Aeciospores large. 



(P. Maiiana\ 

 \P. rubra J 



P. Mariana 



P. rubra 



P. Engelmanni 

 P. site hen sis 

 P. canadensis 



18. P. con si mile. 



Squamicolous. 



Pycnia inconspicuous. 

 Aeciospores small. 



19. P. decolorans 



{ P. excelsa } 



20. P. abietinum. 



Mycelium annual. 



Pseudotsuga : 



Foliicolous. 



P. Mariana 



P. excelsa 



P. Engelmanni 



P, rubra 



P< canadensis 



23. P. c on or urn - 



Piceae. 



Pycnia subepidermal, inconspic 



uous. 



Abies : 



Mycelium annual 



{ P. mucronata } 22. P. Hohvayi. 



Foliicolous. 



Mycelium annual, not forming 



witches' brooms. 



