CAEOMA. 419 



leafless shoots on Thujopsis dolabrata in Japan, whence they were 

 sent to me (Figs. 254 and 255). One example (not figured) was 

 as large as a young child's head. 



The shoots of the witches' brooms are furnished with vascular 

 bundles and possess a parenchyma rich in starch-content. 

 Each branch of the deformed shoot termi- 

 nates in a hemispherical saucer-shaped 

 ca«oma-cushion, at first covered over by 

 the epidermis, but with no peridium. The 

 caeoma-discs are at first brown, but after 

 the epidermis bursts and rolls back, the 

 yellow dusty spores appear. The spores !'•«• 255.— caeoma de/or- 



. ,-t f, mans. Portion of the pre- 



arise serially from very short basidia ; they ceding figure enlarged to 



■^ •^ ' */ 8howthe(7a€oma-dlscsonthe 



are yellow and have striped membranes. ends of twigs, (v. lubeuf 



The witches' brooms also exhibit marked 

 hypertrophy (Fig. 254). In the supporting branch both wood 

 and bark are considerably increased. Large medullary rays occur 

 in the wood, and nests of thin-walled parenchyma are interpolated 

 between the regular tracts of tracheae, so that the general 

 arrangement resembles that shown in juniper by Wbmle's 

 researches on Gymnosporangium. The parenchymatous groups 

 of cells in the wood appear to the naked eye as brown spots. 

 They are permeated by a vigorous intercellular mycelium, which 

 sends off large haustoria into the adjacent cells. 



Caeoma laricis (Westend).^ On needles of Larix. (Britain.) 



C. orchidis A. et S. On orchids. (Britain.) 



C. chelidonii Magn. On Chelidonium majus (U.S. America). 



C. fumariae Lk. On Corydalis. 



C. euonymi (Gmel.). On Eiio7iymus europaeus (Britain). 



C. confluens (Pers.). On Ribes alpinum, R. ruhrum, etc. 



C. nitens {C. himinatwm) is the well-known Blackberry-rust so common 

 in the United States. It is probably a form of Pueeinia Pechiana? 



C. aegfopodii (Rebent.). On Aegopodmm Podagraria and Chaerophyllum 

 aromMicwm. 



C. ligustri (Eabh.). On lAgustriim vulgare. 



C. ari-italici (Duby). On Arum maculatum. 



C. allionim Link. On Allium ursinum, A. oleraceum, etc' 



C. saxifrag-ae Strauss. On Saxifraga granulata? 



C. mercurialis (Mart). On Mercuriodis perennu? 



^ This and most of the other species are only stages of some Mdampsora. 



= Clinton, Botanical Gazette, 1895, p. 116. 



^ These three species are given as British in Plowright's 'Uredineae.' (Edit.) 



