580 FUNGI imperfect:: the imperfect fungi 



is essentially a Phoma with two-celled conidia. (Fig. 191F.) A. pisi Lib. is 

 very destructive to cultivated peas. Its perfect stage is Mycosphaerella 

 pinodes (B. & Bl.) Stone. Diplodia (Phaeodidymae) is like Macrophoma 

 with colored two-celled spores. In fact some species of Diplodia have been 

 described as Macrophoma, Sphaeropsis, and Diplodia, depending upon the 

 age of the conidia. Such species are placed by some authors in Botryo- 

 diplodia. All three types of spores may be present in the same pycnidium 

 and all are viable. The 500 or more described species occur on leaves, 

 stems, etc., and are often the cause of serious diseases of their host plant. 

 Septoria (Scolecosporae) is a genus of over 1000 species, practically all 

 parasites. (Fig. 192B-C.) Like Phoma the pycnidium is immersed in the 

 host tissue and the short ostiole projects to the surface. The conidia are 

 long and slender, often considerably longer than the diameter of the 

 pycnidium, hence are curved within the latter. Two serious diseases of 

 celery are caused by S. apii Chester, and S. apii-graveolentis Dorogin, 

 respectively. S. lycopersici Speg. defoliates the older plants of tomato 

 {Ly coper sicom) and causes enormous losses. The perfect stage of some 

 species of Septoria belongs to the genus Mycosphaerella. Phaeoseptoria 

 differs from Septoria in the possession of colored, instead of essentially 

 hyaline, spores. In the genus Phomopsis two forms of conidia are pro- 

 duced in the same pycnidium; long slender curved stylospores and short 

 ellipsoidal pycnospores. (Fig. 192E-F.) The perfect stage of some species 

 of Phomopsis belongs to the genus Diaporthe in the Sphaeriales. 



Family Zythiaceae (Nectrioidaceae). The pycnidia are bright- 

 colored and waxy, like the perithecia of the Hypocreales. Bender recog- 

 nized 62 genera. Zythia (Hyalosporae) is essentially a Phoma with bright- 

 colored pycnidia. Some species are parasitic. Aschersonia (Hyalosporae) 

 produces its pycnidia buried in a bright-colored stroma with several 

 separate or united ostioles. The stroma is produced externally on leaves 

 or twigs and in some, probably all, cases is parasitic upon insects feeding 

 upon the supporting plant. 



Family Leptostromataceae. The pycnidia have a well-developed 

 upper half but the basal portion is not well-developed. They resemble in 

 many respects the fruiting bodies of some of the Hemisphaeriales. Bender 

 recognizes 88 genera. They are largely leaf-inhabiting saprophytes and 

 parasites. Leptothyrium pomi (M. & F.) Sacc. (Hyalosporae) produces the 

 so-called "fly-specks" of apple fruits. These are the minute flattened, 

 round pycnidia. (Fig. 192D.) Leptostroma (Hyalosporae) produces elon- 

 gated pycnidia with slit-like ostioles, on leaves, stems, etc. Entomosporium 

 maculatum Lev. (Hyalophragmiac) forms four-celled conidia, the cells 

 forming a sort of sciuare, each with a bristle. It causes leaf and fruit spots 

 of the pear. Its perfect stage is Diplocarpon soraueri (Kleb.) Nannf. 

 {Fahraea maculata (Lev.) Atk.), Family Mollisiaceae, Order Pezizales. 



