Preliminary List of Wisconsin Parasitic Fungi. 137 



Spots brown, little, if at all, thickened, slightly pustulate, with a central 

 •cluster of a few spermogonia. Cluster cups usually hypophyllous, concen- 

 trically arranged, rarely a few epiphyllous. Peridium short, whitish; bor- 

 der narrow, about 10-lobed. Peridiai cells colorles?, rugose, usually 

 nearly isodiametric, 20-25 /t. Spores red-orange, polygonal, isodiametric 

 or commonly somewhat elongated, 20 — 25 /.i. 



The spots are generally orbicular, or elliptical with the longer axis par- 

 allel to the midrib. When the spermogonia appear near the margin of the 

 leaf, or near the midrib, the spot naturally develops in but one direction. 

 The species differs from the aecidium of Uromyces euphorbiae C. & P. in 

 the regular arrangement of the cluster cups on round spots, and from the 

 other aecidia occurring on this genus in not deforming the host plant. 



240. Aecidium pentstemonis Schw. 



On Castilleia sessiliflora Pursh,, Pentstemon jiuhescens Sol. and 

 Mimulus ringensLi., in summer. La Crosse, Pammel. 



The aecidia occur most abundantly on the lower surface of the leaf, less 

 frequently above. Spots rounded, slightly thickened, reddish-brown, often 

 yellow-bordered; less evident on Castilleia than on the other hosts. Peridia 

 white, short, scarcely bordered, crumbling into the rows of cell of which 

 they are composed. Spores orange; smooth, 15 — 20 ji in diametex-. 



The form on Pentstemon seems to be A. pentstemonis Schw., and that on 

 Mimulus is scarcely different from A. gerardiae Pk., but neither seems to 

 be very distinct from A. scrophularinanimljasch.., on Scrophularia, in Ra- 

 toenhorst, Herb. Mycol., Ed. 2, No. 374. A uredo (No. 216) occurs in com- 

 pany with the aecidium on Mimulus, but is not evidently conaected with 

 it. 



■241. Aecidium sii latifolii (Fiedler). 



On leaves of Sium lineare Michx. La Crosse, Pammel. 



242. Aecidium compositaeum Winter. 



On leaves of Lactuca canadensis L., Nabalus, sp., Vernonia nove- 

 boraeensis Willd., Eup>atorium, perfoliatumlj., Aster sericeus Yent. 

 and several other species of Aster and Solidago (among the latter 

 S. latifolia L, and S. riddelUi Frank), Silpliium perfoliatum L., 

 Erigeron annuum Pers., E. canadense L., E. strigosum Muhl. and 

 Cyntliiavirginica Don. Madison; Kirkland, La Ci'osse, Pammel. 

 In this conglomeration, which for convenience includes all aecidia found 

 ■on Compositae and not connected with some teleutosporic form, are, per- 

 haps, to be distinguished: A. tenue Schw. (A. compositarum., var. evpatorii 

 Schw.), A. erigeronatum Schw. and A. asteratum Schw. Specimens found 

 at Madison on Taraxacum dens leonis Desf. may prove to be ^4. taraxaci 

 Schm. and Kze., the aecidium of Piiccinia silvatica Schr., of which we 

 have not detected the teleutospores. 



