200 KANSAS ACADEMY OF SCIENCE. 



ERYSIPHEAE OF RILEY COUNTY, KANSAS. 



By LORA L. WALTERS, Manhattan. 



Erysipheae, commonly known as "white mildews," or "blights," may be 

 easily recognized by the white dusty or web-like coating on the outside of 

 leaves or stems or other parts of many common plants. This white coating, 

 the mycelium, consists of numerous slender colorless threads, branching 

 and intercrossing, pressed close to the nost plant. At short intervals they 

 send out special branches, called haustoria, that penetrate the epidermal 

 cells, serving to attach the fungus to the host, and also to extract nourishment. 



Erysiphae are reproduced both asexually by conidia and sexually by 

 sporidia. Chains of conidial cells are formed at the ends of short branches 

 of the mycelium, called fertile hyphae or conidiophores. Under favorable con- 

 ditions these conidia germinate rapidly, sending out slender tubes and forming 

 new mycelium. 



The perithecia containing sporidia are globose, sometimes depressed, 

 bodies seated singly on the mycelium. At first they are colorless, then yellow, 

 becoming dark brown or black when mature, bearing thread-like appendages. 

 These perithecia contain delicate, thin-walled sac-like bodies called asci. 

 These are colorless, more or less oval in shape, usually pedicillate, containing 

 from two to eight sporidia. The sporidia are simple spores, colorless, granular, 

 oblong or oval. The perithecia usually appear late in summer and remain 

 on the fallen leaves over winter. They are not provided with any opening, 

 and the spores escape only by the decaying of the perithecium. 



Linneus, in Species Plantarrum, p. 1186, 1753, describes all powdery mil- 

 dews as one species of fungi, under the name of Mucor Erysiphe. He de- 

 scribes it as follows: "Mucor albus capitulis, fuscis sessilibus. Habitat in 

 foliis Humuli, Aceris, Lamii, Galeopsidis, Lithospermi." 



In all descriptions the original has been consulted, where it was accessible, 

 and copied. These descriptions are inclosed in quotation marks and follow 

 the citation. The citations not consulted are inclosed in quotation marks. 

 Where the original description could not be obtained the next oldest is given. 



This work has been done in the botanical laboratory of the Kansas State 

 Agricultural College. The list is based upon specimens contained in the her- 

 barium of the college. 



SPHAEROTHECA, Lev. Ann. Sci. Nat. 3d S. XV, p. 30 [138] (1851). "My- 

 celium arachnoideum floccosum effusum plerumque persistens. Conceptac- 

 ula globosa, sporangio unico vesiculoso, octosporo farcta; sporae ovatae. 

 Appendiculae numerosae floccosae cum mycelio intertextae." 



S. Castagnei. Lev. Ann. Sci. Nat. Ser. Ill, Tome XV, p. 31 [139] (1851). 

 "Bifrons. Mycelio effuso arachnoideo plerumque evanido. Conceptaculis 

 minutis sparsis globosis. Appendiculis numerosis brevibus sursum flexis." 

 Leville gives a large number of different host plants of widely separated 

 orders. Perithecia abundant 80-100 mmm, appendages usually colored through- 

 out, asci elliptical, sporidia usually eight, variable in size. On Bidens cernua 

 L., B. connata Muhl., Taraxacum Taraxacum (L.) MacM. 



ERYSIPHE Hedw. in DC. Flore Franc. II, p. 272 (1805); Lev. (Emend.) 

 Ann. Sci. Nat. 3d S. XV, p. 53 [161] (1851). The following is the original de- 



