284 BOTANY. 



PodospTuera Kunzei may be found on the leaves of the cherry and 

 apple, which it injures greatly In some cases ; the coiiidia may be ob- 

 served in midsummer, and the sexual process and formation of perithecia 

 in autumn. 



PhyUactinia guttata may be obtained in great abundance in autumn 

 upon the leaves of the hazel and ironwood. 



Uncinula adunca is frequently abundant on willow ieaves in the 

 autumn (Fig. 190). 



U. spiralis is the species to whose conidial stage the name Oidium 

 Tuckeri has hitherto been applied in this country. It occurs on the- 

 grape, and does great injury. According to Dr. Farlow, it is not cer- 

 tain that the so-called Oidium Tuckeri of this country is identical with, 

 what is so named in Europe, and which is even more injurious to 

 grapes in that country than in this. 



U. etrciiiata occurs on the leaves of the red and silver maples in the 

 autumn. 



Mierosphmra Friesii is one of the most common species. It may be- 

 found in the conidial stage at any time during the summer on the 

 leaves of the lilac, and late in summer or in autumn the perithecia are 

 usually abundant. 



■ M. extenaa is a. nearly related species, often very common ou oak 

 leaves. 



Erysiplii lainprocarpa,vi\i\a\\ may be found on Compositae (especially 

 on Helianthus), and also ou wild verbenas, is readily distinguished by 

 its two-spored asci. The commonness of this species makes it a valua- 

 ble one for study. 



E. torlUis may be frequently obtained on the leaves of the Virgin'S' 

 Bower. 



E. Martii occurs in great abundance upon cultivated peas, greatly 

 to their injury. In summer it covers the leaves and fruits with a 

 white mould-like growth, which is the conidial stage of the parasite ; 

 as autumn approaches the mvcelium becomes darker, and finally large- 

 numbers of perithecia may be found. 



E. communis appears in early cummer on grass leaves, where the- 

 vegetation is rank. In autumn the perithecia may be found in abun- 

 dance on Ranunculacese (especially on Anemone) growing in grass. 



Saprophytic Plants. 



Eurotium herbdriorum may be readily obtained for study by placing 

 a few green specimens of Phanerogams in. an ordinary plant-piress and 

 permitting them to remain until they become mouldy. The conidial 

 stage, which first appears, is what has long been described as a distinct 

 fungus under the name of Aspergillus glaucus ; somewhat later the 

 bright yellow perithecia will be found in abundance. 



