560 



HUTCHINSON'S POPULAR BOTANY 



example may be found in the white mould (Mucor mucedo) which appears 

 upon jam, fruit, saccharine fluids and drugs. From the mycele rise hyphce of 

 similar structure upon whose summit is formed a comparatively large 

 spherical sporange whose thin membrane bursts to release the spores. The 

 Potato 'Blight (Phytophthora infestans) and the Salmon Fungus (Saprolegnia 



ferox), an aquatic 

 Fungus, also be- 

 long to this Order. 



The Uredinese is 

 an Order of plant 

 parasites, and the 

 fructification in 

 some species takes 

 the form of the 

 well-known " clus- 

 ter-cups" which 

 burst through the 

 tissues of living 

 plants. In addition 

 to cluster-cups (ceci- 

 dia] there are sper- 

 mogonia, uredo- 

 spores, and teleuto- 

 spores. 



In some species 

 of Puccinia all these 

 grades are passed 

 on the same host. 

 Such species are 

 known as Auto- 

 Puccinice ; but in 

 others, known as 

 Hete.ro -P ace inice, 

 some stages are 

 passed on one plant 

 and the remainder 

 upon a plant be- 

 longing to a different genus. A familiar example of this Hetercecism, as 

 it is termed, is afforded by the Mildew of wheat. The spermogonia and 

 sscidia are found on the Barberry, and known as dScidium berberidis; the 

 uredospores and teleutospores develop on Wheat, and are known as Puccinia 

 graminis. The secidiospores from the Barberry will germinate on the Wheat 

 and produce uredospores and teleutospores which germinate on Barberry. 

 A similar case is illustrated by our photos (figs. 696, 697). The shoots of 



Photo 6y] [E- Step. 



FIG. 696. HAWTHORN CLUSTER-CUPS (Rcestelia lacerata). 



A spindle-shaped mass of secidia which distorts branches of hawthorn, etc. A stage in 

 the history of the Fungus shown on the opposite page. 



