AECIDIUM-FORMS. 411 



Aec. Peckii De Toni and Aec. oenotherae Mont. On leaves of species 

 of Oenothera. 



Aec. sambuci Schwein. On leaves and stems of Samhiicus. 



Aec. ceanothi £11. et Kell. 



Aec. abundans Peck. On species of Symphoricarpus. 



Aec. cephalanthi Seym. On Cephalanthus occidentale. 



Aec. erigeronatum Schwein. Ou many species of Erigeron. 



Aec. astenim Schwein. On species of Astej- and Solidago. 



Aec. polemonii Peck. On Polemonium and Phlox. 



Aec. apocyni Schwein. On leaves of Apocynum,. 



Aec. Jamesianum Peck, and Aec. Brandegei Peck. On leaves of species 

 of Asclepias. 



Aec. myosotidis Burr. On leaves of Myosotis verna, etc. 



Aec. plantag-inis Ces. On leaves of species of Plantago in Europe and 

 America. 



Aec. pentastemonis Schwein. On species of Pentstemon. 



Aec. giliae Peck. 



Aec. lycopi Gerard. Ou leaves and stems of Lycopus europaetts. 



Aec. iridis Gerard. 



Aec. macrosporum Peck, and Aec. smilacis Schwein. On species of 

 Smilax. 



Peridermium. 



Peridermiuiii pini (Willd.)^ is found on pine-trees in Europe, 

 Britain, and United States. A teleutospore-stage of this has not 

 as yet been identified, although a very similar species {Peri- 

 dermium Cornui Eostr. et Kleb.), also occurring on the bark of 

 pines, has been proved to have as its teleutospore-form Cronartium 

 asclepiadeum.^ 



The mycelium of Peridermium pini lives intercellularly in 

 the rind, bast, and wood of Pinus syhestris, P. Zaricio, P. 

 halepensis, P. maritima, and P. montana. It lives and extends 

 through the stem for years, attacking the living cells and 

 absorbing nutriment from them by little haustoria. The cells 

 of parenchymatous tissues are those most generally attacked, 

 and the mycelium has been found to penetrate along the 

 medullary rays to a depth of 10 cm. into the wood-mass. 

 The cells of attacked parts lose their normal content including 

 starch, and secrete crude turpentine in such quantity as to 

 completely permeate their walls, and even to form drops. In 

 this way portions of the wood become completely saturated 



^ R. Hartig, Wichtir/e Kranhheiten d. Waldhdumem. 



^ Klebahn, Beriehte d. dentscJi. hotan. Oesellschaft, 1890. 



