160 Bulletin 313 



"III. Telia hypophyllous, widely scattered, often confluent, pul- 

 vinate, 0.5 mm. or less across, deep, reddish-orange fading to pale 

 yellow; teliospores with walls swelling 20-40 fi above; contents or- 

 ange yellow fading to colorless, oblong, or slightly clavate, 19-23 by 

 60-80 /JL, rounded or obtuse at both ends." North American Flora, 

 V. 7, p. 87 (1907). 



921. Uredospores from leaf of /. hederacea, 1/12. 



Peridermium acicolum U. & E. (= Coleosporium solidaginis 

 Schw., page 162). 



Melampsora medusa (Thiim.) Arthur. — On Populus deltoides. 

 Described by Arthur as follows: 



"O. Pycnia chiefly epiphyllous, scattered or somewhat gregarious, 

 minute, punctiform, pale-yellow, inconspicuous, hemispherical, 

 40-80 jx in diameter, half as high. 



"I, Aecia chiefly hypophyllous, scattered or somewhat gregari- 

 ous, small, 0.1-0.3 mm. broad, round or oblong, pale-yellow fading 

 to white, inconspicuous, formed between epidermis and mesophyl, 

 soon naked, pulverulent, ruptured epidermis noticeable ; aeciospores 

 globoid, 17-22 x 24 /i,; wall colorless, thick, 2.5-3 n, minutely verru- 

 cose, with minute crowded papillae, pores indistinct. 



"II. Uredinia amphigenous, or only hypophyllous, scattered, 

 roundish, small, 0.2-0.4 mm. across, early naked, somewhat pulveru- 

 lent, orange-yellow, fading to pale brownish-yellow, ruptured epi- 

 dermis usually inconspicuous ; urediniospores ellipsoid or obovate- 

 ellipsoid, 15-18 by 22-30 fi, usually flattened laterally; wall colorless, 

 2.5-3 /x, or up to 10 /n on the flattened sides, sparsely and evenly ver- 

 rucose, with fine papillse, except on the flattened sides which are 

 smooth; paraphyses numerous, intermixed with the spores, capitate, 

 smooth, 40-65 ix long, head 14-25 /a broad, wall thick, 3-6 ju, peri- 

 pheral paraphyses thinner-walled and more clavate. 



"III. Telia amphigenous or only hypophyllous, scattered, or 

 somewhat confluent, irregularly roundish, small 0.2-0.4 mm. across, 

 slightly elevated, light reddish -brown, becoming deep chocolate 

 brown, subepidermal; teliospores prismatic, 12-15 by 30-45 /x; wall 

 smooth, ciniiamon-bro\\n, uniformly thin, 1 /x." 



Note: In North American Flora, v. 7, p. 98 (1907), as Uredo 

 tneduscB. 



922. Under side of infected leaf of P. deltoides. 923. Uredospore, 1/12. 

 924. Teleutospore, 1/12. 



