98 SELECTED NOTES FROM 



BOTANICAL. 



Puccinia graminis. — The genus Puccinia is characterised by 

 its spores being divided into two compartments supported on a 

 stalk ; and however much their shape may vary in different 

 species, the plan is the same, These Pucc'mice or "Brands" are very 

 numerous, 52 species being described as British in Cooke's 

 " Handbook." The most common of them is P. graminis^ which 

 may be found commonly on any pieces of straw left lying about ; 

 the difficulty will often be to find a straw free from it. On the 

 straw its appearance is that of a brown, raised patch, of linear 

 shape, which under the microscope is seen to be made up of tops 

 of the spores densely packed together. On making a cross-section, 

 we discover the stalked, uni-septate spores lying side by side. 



Cooke tells us, however, that this form must probably be 

 described as only one condition of a Fungus, which in other 

 stages of its existence shows other and quite dissimilar forms. 

 Thus, the straw Puccinia is preceded on growing wheat by the 

 Uredo form called " Rust." This has a yellowish-brown appearance, 

 and the spores are seen under the microscope to be simply 

 globular, and without a stalk. It is known that these are two 

 states of the same thing, and not two distinct fungi, because one 

 finds sometimes on a leaf a patch showing both stages. This I 

 have myself seen in several instances. 



There is also another well-known Fungus, the yEcidium of the 

 Berberry, which has long been popularly believed to be connected 

 with the Wheat Puccinia. Cooke mentions a village near Yarmouth 

 that was famous for mildewed corn, said to be produced by the 

 Berberry bushes ; and when they were cut down the Corn-Mildew 

 disappeared. This was investigated by De Barry, who made 

 experiments by applying Puccinia spores to healthy Berberry 

 leaves, and succeeded in producing a growth of ALcidium on them, 

 while other Berberry leaves which had not been so treated 

 remained free from it. The subject is interesting and may be 

 studied in Cooke's "Fungi," Vol. 16 of the International Scientific 

 Series. It is curious to note how different the two Fungi are in 

 appearance. 



G. D. Brown. 



[The conclusions stated above, with respect to the connection 

 between Corn-Mildew and the ^cidium of the Berberry, do not 

 as yet command universal assent : — authorities differ on the 

 subject, and it may therefore be regarded as being still under 

 discussion. — Edit07-. 1 



