14S JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Pears, Apples, Hawthorns, and other Rosacese, as well as 

 Junipers and other Conifers. 



Tubeuf says that one and the same Gymnosporangium can 

 produce various forms (so-called species) of Bosstelia ; and that 

 different species of this Uredine may be made to infect the same 

 host-plant. 



If G. clavarieforme is sown on Cratasgus, it produces 

 Boestelia cornuta. On the Mountain Ash and on Cydonia 

 vulgaris it only goes so far as to produce spermogonia. On 

 other hosts it grows and infects the leaves, but does not get 

 beyond the production of yellow humps. 



When the same Gymnosporangncm was sown on various 

 species of Crataegus, Tubeuf says he got both Boestelia lacerata 

 and B. cornuta, though these two forms have usually been 

 supposed to belong to separate species. No results were ob- 

 tained on Apple, Sorbus aria, Medlar, &c. 



Whether further researches show that these results are 

 confirmed or not, it is certain that we have in these forms of 

 Gymnosporangium and Boestelia parasitic fungi which are 

 highly polymorphic,* and heteroecious between Cupressine^ and 

 Eosace^e (as many other " Rust -fungi " are between Gramineae 

 and dicotyledonous plants), causing diseases of the cortex and 

 wood of the one, and of the leaves in the other. Obviously it is 

 advisable to take these facts into account where it is wished to 

 -grow either of these classes of plants in the best way. 



V. Othee Conifees. — Conclusion. 



Agaricus mellcus is recorded by Farlow as occurring on 

 Chamoicyimris spliaroidea (Spach.), and the same authority 

 mentions Botrytis vulgaris on Sequoia ; whether these are 

 parasitic, I do not know, and in fact the whole of the very long 

 list of American Conifer-fungi wants careful overhauling before 

 we can decide as to their share in producing diseases. 



I have found the roots of Wellingtonia badly infested with 

 mycelium which seems to be that of a Hymenomycete ; and 

 Araucarias occasionally suffer from similar forms. 



The Yew seems to be very little affected with fungi ; at least 



* I purposely omit discussion here of such points as Kienitz-Gerloff'g 

 discovery of alleged Uredo-spores among the Teleuto-spores of these fungi. 



