Nebraska Forest Fungi. II 



Podosph&era 



Perithecia globose or somewhat flattened. ASCIIS solitary. 

 Appendages confined to a small apical group or scattered over 

 the whole upper half of the perithecium, dichotomously branched 

 at the tip, branches simple and straight, or commonly swollen and 

 knob-like at the tips. 



Podosphaera oxyacanthae (DC.) DeBary. 



The perithecia of this genus resemble those of Micro- 

 sphaera very much. The greatest difference is that here they 

 contain a single ascus while in Micros phaera there are usually a 

 number of asci. The above species occurs upon both sides of 

 the infected leaf, the woolly mycelium being persistent in patches 

 or wholly evanescent. The perithecia are scattered or clustered. 

 The spreading appendages number from 5 to 30, and are dark 

 brown for about half their length the tips are 2-4 times dichoto- 

 mously divided, the branches usually short and equal, with the 

 ultimate branches knob-like. On : Amclanchier bortryapium, Pru- 

 uus amcricana, P. besscyi, P. dcmissa, P. serotina, P. virginiana. 



Podosphaera tridactyla (Wallr.) DeBary. 



It is a question whether or not this species may be a mere 

 variety of the above species. Its small apical cluster of erect 

 appendages seems to separate it quite well from P. oxycanthae. 



Uncinula 



The character that distinguishes this genus from all others 

 is its free, simple appendages which 

 are recurved or coiled at the tip. The 

 perithecia are globose, and there are 

 many asci. 



Uncinula macrospora Peck. 



Uncinula has characteristic ap- 

 pendages in that the tips are very 

 typically coiled or uncinate. The my- 

 celium covers both sides of the leaf, 

 and is usually evanescent. In this 

 species the perithecia are closely gre- 

 garious in small patches or scattered 

 evenly over the whole leaf. The ap- 

 pendages are numerous, 50-130 or 

 Fig. 15. Uncinula. a. Peri- more, simple, smooth colorless, with 

 thecium with appendages, b. the tip simply coiled. Very common 

 Ascus with spores. Highly on Uh amcricana. See fig. 13 

 magmfied and 15. 



