IOWA ACADEMY OF SCIENCES 
109 
almost black. Appendages of various kinds develop from different por- 
tions of the perithecia. Asci arise from the base of the perithecia; they 
are thin-walled, colorless, oval, ovate, oblong or even nearly spherical, 
usually have a short pedicel and contain from two to eight hyaline oblong 
or oval spores. The spores escape by the rupture of the perithecia as 
they are not provided with an openingk 
The powdery mildew's are frequently affected by a parasitic fungus, 
Cicinol)olus cessatii, which especially attacks the mycelium, conidia and 
conidiophores of the summer stage. The spores of this fungus also are 
contained in a brownish perithecium. Burrill and Earle call attention 
to the presence of the Cicinobolus spores in the perithecia of the host and 
they say as follows concerning this fact: 
“Occasionally, on rupturing a perithecium, it will be found to contain 
minute bodies like Cvcinobolus spores, instead of asci. This is considered 
a fourth kind of leproductive bouy by Berkeley (Introduction to Crypt. 
Bot. p. 78). It is more likely a case of the Gicinoholus developing its 
fruit wdthin the grcwung perithecium.” 
I agree with these writers that these are simply the pycnidiospores of 
the CicinoboJus. It is a not uncommon occurrence on Erysiphe cichora- 
cearum. 
The Erysiplieae have been worked over by quite a number of investi- 
gators and no attempt wall now be made to review the literature on the 
subject. The most extensive monograph is that by Salmon^ Of the spec- 
ies most commonly found in the Rocky Mountains mention may be made 
of Podosphaera oxycantliae, Phyllactinia suffulta, Microsphaera quercina 
and TJncinula salicis. 
Podosphaera oxyacanthae, (Dec.) D.By. The Powdery Mildew' of the Plum 
and Cherry. 
History. This fungus was described as Erysiphe oxycantliae by De- 
Candolle^ Wallroth^ uses the name Alphitomorpha tridactyla W. Leveille®, 
however, named it Podosphaera oxycanthae (D. C.) DB.® 
The species is wddely distributed not only in Europe but in eastern 
North America, and in some places is abundant in the Rocky Mountain 
country. 
General Ciiakactees. This fungus develops its mycelium on both 
surfaces of the leaf, but usually on the upper where it produces a white, 
powdery, mealy substance, either in definite places or sometimes covering 
1 . The different genera are arranged as follows by Burril & Earle in the 
Parasitic Fungi of Illinois. Bull. III. Sta. Lab. Nat. Hist. 2 : 392. 
*‘Spliaerotlieca. — Peritheceium containing a single ascus, appendages floccose, 
undiviuecl. 
Podosphaera. — Perithecium containing a single ascus, appendages dichotom- 
ously divided at the tip. 
Uncinula. — Asci several, appendages coiled at the tip. 
Phyilactinia. — Asci several, appendages straight, rigid, swollen at base. 
Microsphaera. — Asci several, appendages floccose, undivided.” 
2. Monograph of he Erysiphaceae Hem. Torrey Bot. Club. 9. 
Supplementary notes on Erysipheaceae Bull. Torrey Bot. Club 29 : 183. 
3. FI. Fr. f) : 106. 1815 1 : 10. 
4.1 Compendium FI. Germ, 4 : 753. Ann. Wett. 4 : 226. 
5. Ann. Sci. Nat. III. 15 : 135. PI. F. f. F. P. Lev P clandestine Lev 
6. Morph. II. An. Phys. d. Pilze. 3 : 480. 
