GAUl'OPEYTA. 183 



ingly injurious species ; they often attack and destroy not 

 only plants, but also insects, upon which their ravages are 

 in many cases yery great. 



336. Some Black Fungi, constituting the family Verru- 

 cariacecB, are parasitic upon unicellular or few-celled plants, 

 protophytes and phycophytes, and are commonly known as 

 " lichens." Their general structure is much like that of the 

 lichen-forming species of the next order (par. 342 to 347). 



Practical Studies. — {a) In early summer examine the Choke-cherry 

 and Plum trees (wild and cultivated) for the young stages of Black 

 Knot. Watch the development until the knot becomes velvety in 

 appearance (about midsummer). Now make very thin cross-sections 

 of the knot and examine for conidia. The several stages may be 

 readily preserved in alcohol for future study. 



(6) Late in autumn and in early winter examine the knots on the 

 same trees. Note the young perithecia, i.e., hollow papillae. Make 

 very thin vertical sections through some of these. No perfect spores 

 can be found at this time. 



(c) Collect fresh knots in midwinter and make similar examinations, 

 when the sacs and spores will be found. 



Systemaiic Literature.- — Ellis and Everhart, North American Py- 

 renomvcetes, -58-758. Saccardo, Sylloge Fungorum, 1 : 88-766 ; 

 2 : 1-813. 



337. The Cup-fungi (Order 15. Discomtcete^). — The 

 common Cup-fungus of the woods is a typical representa- 

 tive of this order. The familiar cup- or saucer-shaped 

 growth is in reality the spore-fruit, while the plant itself 

 generally grows underground. The plant consists of 

 whitish jointed filaments which grow on or in the ground, 

 drawing their nourishment from decaying sticks, roots, 

 etc. 



338. But little is known as to the asexual reproduction, 

 but in some species conidia much like those in the preced- 

 ing orders have been observed. 



339. The sexual organs are produced by the swelling up 



