412 



Arthur and Kern : Peridermium 



Pycnia subepidermal. 



Pycnia inconspicuous. { A, grandis } 



Pycnia subcuticular. 



Pycnia slightly convex. 



Peridia cylindrical. { A. pectinata } 



Peridia flattened 

 laterally. 

 Pycnia hemispherical. 



Peridia cylindrical. 



Mycelium perennial, forming 



witches' brooms. 



Pycnia subcuticular, hemi- 

 spherical. 



{A. lasiacarpa} 



A. bahamea 

 A. grandis 



A. balsa mea 

 A. lasiocarpa 

 A. religiosa 



Tsuga : 



Foliicolous 



Pycnia subcuticular, inconspicu- 



ous. 



Mycelium perennial, form- 

 ing witches' brooms. 



T. canadensis } 



Larix : 



Foliicolous. 



Pycnia subcuticular, inconspicu- 



ous. 



Mycelium annual. 



[ L . decidua } 



\ 



Ephedra ; 



Caulicolous. 



Pycnia subcuticular, conspicuous 



Mycelium perennial. 



E. Torreyana 

 E. cali for nic a 



E. nevadensis 

 E. trifurca 

 E. pedunculata 



21. P. pseudo-balsa- 



meum 



24. P. column a re. 



25. P. ornamentale 



28. P. balsameum. 



27. P. el at in um. 



26. P. Peckii. 



29. P. Laricis. 



30. P. Ephedrae 



i . Peridermium delicatulum sp. no v. 



0. Pycnia amphigenous, numerous, scattered, conspicuous, 



brownish, dehiscent by a longitudinal slit, subcorticular, large. 



0.3-0.4 mm. broad by 0.5-1 mm. long, low-conoidal, 80-ico/; 

 high. 



1. Aecia amphigenous, from a limited mycelium, numerous, 

 scattered on discolored spots occupying part of a leaf, erumpent 

 from longitudinal slits, 1-5 mm. long ; peridium colorless, delicate, 

 scarcely protruding above the ruptured epidermis, cells isodiamet- 

 ric, slightly or not overlapping, 20-25 I 1 l° n g> walls transversely 

 striate, inner finely verrucose, 4-5 /1 thick, outer walls slightly 

 thinner; aeciospores ovoid or cuboidal, 19-21 by 21— 28 «, con- 



