SOME BRITISH RUST FUXGI IGl 



SOME BRITISH RUST FUNGI. 

 Br Malcolm Wilson, D.Sc, F.L.S., 



Lecturer in Mycology, University of Edinburgh. 



In this Journal for 1915 (pp. 43-49) an account was given of 

 the occurrence of several alpine species of the Uredinese ; the follow- 

 ing notes supply additional information on some of these and record 

 tlie occurrence of several others. The British Bust Bungi by W. B. 

 Grove has been of great help in the determination. 



Melampsora alpina Juel. 



The uredo- and teleutospore stages of this species on Salix her- 

 hacea have already been recorded (Ber. d. schweiz. bot. Ges. ix. 49) 

 from Ben Lui. A further search was made on Ben Lui on July Ist^ 

 1915, and the secidial stage was discovered on Saxifraga oj^ijositi- 

 folia, growing at an altitude of about 2500 ft., in close proximity to 

 Salix herhacea, which was bearing young uredospore sori. Only a 

 singh' secidium was discovered, and no spermagonia were found on 

 the leaf, although these were probably present at an earlier date. 



The aicidial stage, which has been knoAvn as Cceoma SaxifragcB 

 Wint., has been found in Switzerland by Jacky (Ber. d. schweiz. bot. 

 Ges. ix. 49), who proved the connection between the tw^o stages by 

 carrying out infection experiments with both secidiospores and teleu- 

 tosix)res. The Scottish specimen agrees closely with his description. 



The complete description of the species is as follows : — 



Spermagonia. Several, epiphyllous. uEcidia, Solitary, epiphyllous, 

 orange-red, at first covered by the epidermis ; spore layer flat ; spores 

 spherical or polygonal, 17-25 x 16-24 ^, wall colourless up to 3 ^ in 

 thickness ; paraphyses colourless, filled with yellow granular contents, 

 ending in a swollen head which is always smaller than the secidiospoi-es. 

 Uredosjjores. Sori small, scattered, rounded, amphigenous, orange- 

 yellow ; spores ellipsoidal or spherical, 19-22 x 14-17 fx, finely echinu- 

 late, contents orange-yellow ; paraphyses abundant, capitate, thick- 

 walled, up to 88 fjL long, head about the same size as uredospores, 

 wall up to 5 ^t in thickness. Teleiitospores. Sori amphigenous, 

 mostly epiphyllous, rounded, up to '8 mm. in diameter, brownish 

 black, covered by the epidermis ; spores flattened or rounded at the 

 apex, rounded and usually diminishing in size towards the base, 

 2(3-50x9-14/7, wall thin, smootli yellowish brown. 



^cidia on Saxifrago oppositifolia L., Switzerland and on Ben Lui, 

 Scotland. July and August. Uredo- and teleutospores on Salix 

 herhacea L., Norway, Sweden, Switzerland and on Ben Lui, Scotland. 

 J uly-October. 



The discovery of the secidial stage clears up any doubt as to the 

 distinctness of this fungus from M. arctica Rost., a species also 

 growing on Salix herhacea and closely resembling M. alpina in its 

 uredo- and teleutospore stages, but apparently autcecious. 



