147 
THE UROMYCES OF EUPHORBIA. 
By P. Magnus * 
Professor Kornicke, in No. 3 of “ ITedwigia ” for 1877, refers 
the Uromyces growing on Euphorbia Gerardiana and Euphorbia 
verrucosa — and, according to him, also on Euph. Cyparissias — to a 
new species ( Uromyces Icevis , Korn.), which he distinguishes from 
Uromyces scutellatus, Ley., by the smooth membrane of the 
Teleutospores. At the meeting of the Association of Naturalists 
on the 20th March, 1877, I endeavoured to prove that this 
Uromyces corresponds with the old Uredo excavata , DC., and it 
seems advisable to me to give here my arguments for the benefit 
of the readers of “ Hedwigia.” 
On our ordinary Euphorbiacece, Tithymalus Cyparissias and 
Tithymalus Esula grow a Uromyces and a TEcidium , both of 
which originate the same degeneration of the vegetative powers 
attacked by them, and both grow on them in the same characteristic 
manner ; while their Mycelium pervades the whole of the attacked 
vegetative system, and their Spermogonia and Teleutospore 
stroma, or iEcidium cups, are spread over the whole expanse of 
all the leaves of the attacked vegetation, or of the affected part. 
All fungologists (myself included) had hitherto assumed — princi- 
pally from analogy — that both these fungi, the Uromyces and the 
iEcidium, in the circle of evolution belonging to one Fungus, 
were different fructifications of one and the same fungus. So 
surprising were the observations of Chief Staff Surgeon Dr. 
Schroeter that the spores of JEcidium Euphorbice when sown on 
the leaves of our Pea, Pisum sativum , L., sprouted there as 
Stylospore pustules of Uromyces Pisi, Strauss. (“Hedwigia” 
xiv., part 1875, p. 98). It is correct that an iEcidium never 
grows on Pisum sativum , L. But, nevertheless, I had hitherto 
imagined that Uromyces Pisi belonged to an Uromyces which was 
only unable to attain to the formination of the iEcidium fructifica- 
tion on the special foster plant, Pisum sativum , L. ; while it grows 
in all its forms of fructification on the nearly allied tares, Vicia 
angustifolia , Rth., Lathyrus montanus , Bernh., &c. On these grow a 
very closely allied and long-stalked Uromyces, which Schroeter 
denotes Uromyces Viciae Fabce (Pers.), and distinguishes from 
that which grows on the Pisum by the great thickening of the 
apex of the Teleutospores. That a parasitical fungus does not 
develop all its fructifications on certain allied plants, is frequently 
the case. Thus, the Puccinia Compositarum , Schl., produces on 
the Taraxacum officinale all its forms of fructification, but it never 
produces iEcidium on Hieracium Pilosella ; and thus, in an 
analogous manner, Cystopus candidus , Pers., grows on very many 
CrucifercBj but forms Oogoniae on very few species. Therefore, the 
above-mentioned observations of Dr. Schroeter surprise me in 
many respects. 
* Translated from “ Hedwigia’’ for May, 1877- 
