348 THE FUNGI WHICH CAUSE PLANT DISEASE 



longed into sharp points. Spores borne singly on pedicels, ellipsoid ; 

 wall colorless, echinulate, pores indistinct. 



III. Telia indehiscent, forming evident layers immediately 

 beneath the epidermis. Spores oblong or prismatic, 1-celled; 

 wall smooth, slightly colored. 



M. betulse (Schum.) Arth. occurs, O and I on larch, II and III on 

 Betula. 



Melampsorella Schroter (p. 341) 



0. Pycnia hemispherical, without ostiolar filaments. 



1. iEcia erumpent, definite, oblong, buUate. Peridium color- 

 less, with thin-walled cells. .Sciospores ellipsoid; wall colorless, 

 thin, verrucose, without smooth spot. 



II. Uredinia barely protruding through the epidermis, dehiscent 

 by a central pore. Peridium hemispherical, delicate, cells slightly 

 or not enlarged at orifice. Urediniospores borne singly on pedicels, 

 obovate to ellipsoid; wall slightly colored, echinulate, pores ob- 

 scure. 



III. Telia effused, indehiscent. Teliospores globoid to ellipsoid, 

 1-celled; wall smooth, colorless, thin. 



M. elatina (A. & S.) Arth.^"* 



0. Pycnia epiphyllous, few, scattered, punctiform, inconspicu- 

 ous, subcuticular, not extending much into walls of epidermis, 

 depressed-hemispherical, small, 100-130 /x broad, 40-50 /x high. 



1. ^cia from a perennial mycelium, dwarfing the young shoots, 

 and forming witches' brooms, hypophyllous, forming two ir- 

 regular Unes, deep-seated, wholly dropping out of the substratum 

 at maturity, roundish or irregularly oblong, large, 0.5-1 mm. 

 across, bladdery, soon open by falling away of the upper part; 

 peridium colorless, dehiscence irregular, cells with thin inner and 

 outer walls; seciospores broadly ellipsoid, or nearly globoid, 14- 

 18 X 16-28 n; wall colorless, thin, 1-1.5 fi, closely and rather 

 finely verrucose. 



II. Uredinia amphigenous, scattered or somewhat grouped, 

 small, round, 0.1-0.4 mm. across, orange-red when fresh, pale- 

 yellow when dry; peridium hemispherical, dehiscent by a small 

 central orifice, cells elongate at sides, polygonal above, inner and 

 outer walls same thickness; urediniospores ellipsoid or obovoid, 



