EXOBASIDIUM. 427 



Ex. rhododendri Cram. (]5ritain and U.S. America). Thiy 

 causes gall-like outgrowths on the leaves of the Alpine-rose 

 {BJwdodcndron ferrugincum and Bli. hirHi/funt). The swellings 

 may be small and fairly hard, or, attaining the size of cherries 

 or plums, they may be soft and spongy so that they shrivel 

 u]) isoon after the twig is cut; in colour they are yellowish- 

 white, l)ut ou tlie side exposed to sunlight become rose-red ; 

 the U.robasidimn-gedh nuiy even be formed on tlie small rolled- 

 up leaves caused by attacks of mites. 



Ex. Peckii Hals.^ [This species occurs in the flowers of 

 Andromeda Maridnd in the United States. It is confined 

 almost entirely to the inflorescences, and causes considerable 

 distortion. The l)ell-shaped corollas are replaced l)y ones quite 

 polypetalous, and the ovary becomes raised above the re- 

 ceptacle.] (P]dit.) 



The following five species have been i-econled on Ericaceae 

 in America : 



Ex. azaleae J't-rk. On lihododendron nud{tforuin. 



Ex. discoideum Kllis. On Rhododendron viscostini. 



Ex. decolorans JIaik. On Rhododendron viscosnm and A', occidentak'. 



Ex. arctostaphyli Haik. On Arctos^taphiilos pumjcn^. 



Ex. cassandrae I\'<,-k. On ('<fssandra calyctdatu. 



Otlier s))('cie.< to \w mentioned are: 



Exobasidium ledi Kai><t. On Ledum palustre. 



Ex. Warmingii IJosti'. (L'.S. America). This oec-ur.s on Saxifruga Aizoon, 

 S. bn/oides, S. a,yjera, etc ; it causes marked hypertrophy of the leaves, and in 

 this way, as well as by its many smaller spores, is distinguished from : 



Ex. Schinzianum Magii. On the leaves of Saxifraga rotundl folia, causing- 

 wiiiti.sh spots wiiich soon become bi'own and die. 



Ex. symploci Ellis. On Symplocns thuioria in North America. 



Ex. graminicolum Bres. On leaves of various grasses, e.g. Bromvs, 

 Arrhenathertim, etc. 



Ex. lauri (Tcyl.- is .said to produce bramhed outgrowths of over three 

 feet in length on Lmiriix nobili.^ and A. i-ii,i(irii'n,<i!< in the Canary Islands. 



Urohasidium rostratum Giign. occurs on the '' witches' broom," out- 

 growths cau.sed by Taphrina cornu-cervl Ghgn. on Aspidmm aristahtm 

 in India. 



'Halsted, Bid/etm of the Torrey Club, x.\., 189:i, p. VXl. 

 ■-(ieyler, Botau. Zeituwi, 1874, p. 322, I'l. VII. 



