310 BOTANICAL GAZETTE. 



2. P. Haestedii Farlow. 



Proc. Am. Acad. XVIII. 72. 



Exs. Ellis N. Am. Fung. 209, 210. 



Mycelium with oval haustoria. Gonidiophores rather stout, 

 undivided below, above with numerous 1 to 4 pinnate horizontal 

 branches, the lower of which are considerably longer and more 

 compound than the upper. Tips long, slender, acute, loosely 

 diverging. Conidia oval or elliptic, 19-30/7. by 15-26,:/.. Oospores 

 23-30// in diameter, yellowish, thin walled, exospore with a few 

 folds or ridges. 



On Ambrosia artemisicefolia, Eupatorium purpureum, Bidensfrondosa, Rndbeckia 

 laciniata, SUphium terebinthinaceum, Ilelianthus slrumosus, H. doronicoides, II. tube- 

 rosum, and Solidago Canadensis. Oospores on II. doronicoides. 



From Mass. (Farlow) to Illinois (Burrill, Seymour), Iowa (Bessey, Arthur), 

 Wisconsin (Trelease), and south to New Jersey (Ellis). 



A widely diffused and apparently common species in the Northern States, 

 but not yet reported from the Southern States. It may be expected to occur on 

 almost any of the Tubuliflorce in midsummer and autumn. It can be distin- 

 guished from P. viticola by the more pyramidal outline of the conidiophores, the 

 lower branches of which are usually decidedly longer than the upper, while in 

 the ordinary forms of P. viticola the branches are all short, and by the longer 

 less compact tips. The present species varies considerably, the form on 

 Helianthus being very much branched and forming prominent woolly patches on 

 the leaves, while in the form on Ambrosia the spots are minute and the branch- 

 ing less compound. 



3. P. obducens Schroeter. 



Hedwigia XVI. p. 129. Sept. 1ST? ; Bull. Buss. Inst. II. 234; Proc. Am. Acad. 



XVIII. 70. 

 Exs. Ellis N. Am. Fung. 207. 



Mycelium varicose, haustoria rather large, spheroidal. Conid- 

 iophores long and slender, branches slender, flexuous, loosely 2 

 t<> 3 pinnate, diverging in all directions, inserted rather acutely. 

 Tips slender, acute. Conidia small, oval or ellipsoidal, 15-20// by 

 12-15//.. Oospores 30-40// in diameter, exospore yellowish, 

 nearly smooth. 



On Impatiens fulva. 



Mass. (Farlow) to Illinois (Seymour) and Iowa (Bessey). Europe. 



The species appears in the spring on the cotyledons, whose under side is 

 densely covered by the conidia. Later in the season it forms small scattered 

 spots on the leaves. The species is distinguished from the preceding by having 

 the branches regularly arranged so that they diverge in all directions, while in 

 the preceding they are very irregular, or with a tendency to a distichous ar- 

 rangement. In this species the branches are not usually inserted at right 

 angles, as in the preceding, but somewhat acutely. The tips are sharp and 

 straight, but not so closely consolidated at the base as in related species. 



