THE FUNGI WHICH CAUSE PLANT DISEASE 337 



able yet not inter-inoculable. The aecial stage is found on 

 leaves of conifers, the telia on a large variety of hosts. 

 C. ipomoeae (Schw.) Burr. 



and I. Unkno\vn. 



II. Uredinia hypophyllous, widely scattered or somewhat 

 clustered, 0.25-1 mm. across, early naked, orange-yellow fading to 

 white, ruptured epidermis usually inconspicuous; spores ellipsoid, 

 13-21 X 18-27 M, more or less angular and irregular; wall thin, 

 1-1.5 fi, closely and noticeably verrucose. 



III. Teha hypophyllous, widely scattered, often confluent, pul- 

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

 yellow; spores with wall swelling 20-40 fi above; contents orange- 

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

 60-80 yu, rounded or obtuse at both ends. 



Common on various Ipomoeas and their kin among them morn- 

 ing glory and sweet potato.^'* 



C. soUdaginis (Schw.) Thiim.*'' ^'^""^ 



O. Pycnia amphigenous, scattered, numerous, originating be- 

 tween mesophyll and cortical layer, noticeable, 0.3-0.5 mm. ■nade 

 by 0.5-0.8 mm. long, dehiscent by a longitudinal slit, low-conoidal, 

 80-100 M high. 



1 ( = Peridermium acicolum). Mcia from a limited mycelium, 

 amphigenous, numerous, scattered on discolored spots occupying 

 part of a leaf, erumpent from longi- 

 tudinal slits, tongue-shaped, 0.5-1 mm. 

 long by 0.5-0.7 mm. high; peridium 

 rupturing irregularly, moderately firm, 

 white, cells overlapping, 35^5 n long, 

 not much narrower, walls transversely 

 striate, inner coarsely verrucose, thick, 

 5-6 /i, outer less rough and somewhat 

 thinner; spores ellipsoid, 20-25 x 

 28^0 m; wall colorless, closely and 

 coarsely verrucose with deciduous tu- 

 bercles which are directed away from a smooth spot extending 

 up one side, thick, 2-3 m on the smooth spot, increasing to 

 5-6 fi on the opposite side, including the tubercles. 



II. Uredinia hypophyllous, rarely also epiphyllous, irregularly 



Fig. 250.— Stages O. and I. of 

 Coleosporium solidaginis 



{Periderniium) on Pinua 

 rigida. After Clinton. 



