Descriptive Catalog 



UREDINE^, De Bary. 



Parasitic plants of minute size, growing in the tissues of 

 living pheenogams, or, in a few cases, of living vascular cryp- 

 togams; mycelium articulated, variously branched, penetrating 

 or growing between the cells of the host; spores usually pro- 

 duced by constriction, singly or in chains, from the ends of 

 fertile hyphae (mycelium branches), formed beneath, rarely 

 within the cells of, the epidermis, which is ultimately ruptured; 

 spore or fruit forms of different kinds, viz: Kcidium and spermo- 

 goniiim, uredo and telentoforms. 



The Uredinea? are parasites, and affect a very large number 

 of the species of the higher plants, being found most often up- 

 on the leaves, but also in some instances upon the stems and 

 parts of the flower or fruit. The roots alone are free from 

 their intrusion, and these probably because protected by the 

 soil. 



The most remarkable thing concerning the Uredineaj is 

 their peculiar alternations of fruit forms — "dimorphism," 

 •'polymorphism," or " pleomorphism." The teleutospores, the 

 last in the series, and usually the only ones surviving over win- 

 ter, upon germination emit a slender tube called the promyce- 

 lium. This is never very long or complex in structure, but 

 may be with or without septa, simple or branched. It produces 

 at once, on minute stalks (sterigmata), one to several thin- 

 walled, more or less globular bodies, rich in protoplasm, and 

 known as sporidia. These in turn soon germinate by sending 

 out a little tube, which, upon the proper host, penetrates the 

 tissues and forms the mycelium or vegetative structure of the 

 parasitic plant. Then follow in order, as products of the my- 

 celium, the fruit forms known asspermogonium, aecidium, uredo, 

 and teleutospore. The two first are usually produced simul- 



