72 THE PLANT WORLD 



ing mention it that on Poa. Unlike all other grass and 

 sedge rusts coming under our observation during the day, 

 this one exhibited not only the wintered teliospores, but also 

 some freshly developed uredinia : either the infection had 

 come from occasional urediniospores which had withstood 

 the vicissitudes of the winter, or it had arisen from aecio- 

 spores derived from the spring crop on the alternate host. At 

 first we were inclined to the former explanation, especially 

 as we never could find a uredinially rusted Poa growing in 

 contact with a plant hearing mature aecia of Aec'idium 

 VI on oil //111 Peck, with their brilliant yellow spores. This 

 aecial form belongs to a rather small class in which the 

 mycelium Is either perennial in the tissues of the host, or Is 

 derived from the previous season's Infection, thus enabling 

 It in either case to bear aecia as soon as the host begins Its 

 spring growth. From the fact that the aecia Avere so early 

 that there had clearly been time to Infect the Poa and dev-elop 

 the uredinia, together with the fact that the infested Arahis 

 and the Infested Poa appeared to be near one another, we 

 reluctantly concluded that they might be genetically 

 connected, although we could not secure the additional evi- 

 dence of immediate juxtaposition. Plants of Arabis from an 

 uninfested locality, and resting spores of the Poa rust were 

 secured, and cultures will be attempted later to decide the 

 question.* 



* Another rust calling for elucidation was found on 

 Al/'uiiii, evidently the Pitcciitia inntahUis D. & H. Vhe dark 

 green leaves of the AUium, only a few millimeters wide and 

 ten to fifteen centimeters long, bore golden yellow uredinia, 

 usually near the tips, that were very readily seen. So close 

 to the uredinia on each leaf that one could believe them to 

 arise from the same mycelium, and usually nearer the tip, 

 were telia, sometimes freshly opened, but more often old 

 and dried. The problem was how this autoecious species, 



* Cultures did not confirm the inferem-e of g-enetio connei-tioii, altliiiiii;li 

 they (lid not entirely (li.spro\e it. see Jour. Myc. 14:12. liios. 



