OBSERVATION OF COMMON FUNGI. 
253 
tudinal furrows or lacunae side by side and overlapping, and no 
single one extending the full length of the stem, though some 
furrows are nearly as long as the stem. The plants are one to 
three inches high, the stems about one-half inch in diameter. If 
the plants are found, compare them with the Gyromitra. 
Helvetia infula is a large plant, dark brown in color, and the 
cap is somewhat convoluted, resembling the Gyromitra. 
Summer Cup Fungi. 
There are a great many summer cup fungi which grow on 
ground, or on sticks, weeds, rotting stumps, logs, etc., and even 
on dung. Some are quite small, and the various kinds vary from 
the size of a pin-head up to two to four inches in diameter. Ob¬ 
servations can be made on different kinds, noting size, form, 
color, presence or absence of hairs, etc., and their habitat, i. e., 
where and on what they grow. 
There is one large cup fungus which can sometimes be readily 
grown in greenhouses during the winter. I have for several 
years observed that Peziza vesiculosa grows on excelsior when 
that is packed on the ground in our greenhouses between boxes 
or pots where it is kept rather damp by moisture from manured 
soil. The cups in this plant are often two to three inches in 
diameter, sometimes several growing together. 
The Powdery Mildews. 
These are very common fungi parasitic on leaves, stems and 
fruits of many cultivated and wild plants. The mycelium of 
most of the species grows on the outer surface of the host (the 
host is the plant on which the fungus is parasitic) where it forms 
delicate cobwebby white threads. These threads form erect 
branches which divide up into a necklace-like chain of spores or 
conidia which are white and produced in such numbers as to give 
the leaf or stem the appearance of having been powdered. 
The common lilac, the choke cherry, elm and oak leaves, wil¬ 
lows, etc., are very commonly affected. When the leaves are 
well powdered examine them with a hand or pocket lens. With 
care, the delicate necklace of white conidia can be seen. In a 
