MELAMPSORA 



355 



chains, ellipsoid to polygonal or subclavate, 18 — 28 x 10 



epispore colourless, about 2 /x thick, 



rather densely verruculose, with no 



perceptible germ-pores; no para- 



physes. 



Teleutospores. Sori hypophyllous, 

 subepidermal, small, roundish, red- 

 dish-brown, then dark-brown ; spores 

 prismatic, more or less rounded above, 

 pale-brown, 28 — 40 x 10 — 17 //,; epi- 

 spore thickened (up to 3 p,) above. 



-18^; 



Fig. 265. M. Hypericorum. 

 a, teleutospores, under the 

 epidermis ; b, ascidiospore, 

 without paraphyses. On 

 H. Androsaemum. 



On Hypericum Androsaemum, H. humifusum, H. perfora- 

 tum , H. pulclirum. Not common. May — October. (Fig. 265.) 



What was described by Plowright as the uredo-stage of this fungus is 

 stated by Fischer, Tranzschel, and others, to be the caeoma stage — the 

 spores " being produced in short chains, with sterile intercalary cells, 

 without paraphyses, but sometimes " (at least on Hypericum montanum) 

 '• surrounded by a layer of swollen colourless cells which might almost be 

 considered as an undeveloped peridium." Midler considers the form on 

 H. montanum as a biological race, since he could not infect other species 

 of Hypericum with spores from it. 



But Klebahn has proved (Zeitschr. f. Pflanzenkr. 1905, xv. 106) that a 

 species of Hypericum can bear both the cseorna-forrn without paraphyses 

 and the uredo-form with paraphyses. McAlpine (Rusts, p. 192) records 

 that in Australia the uredo-sori have very abundant paraphyses, inter- 

 mixed ; he describes them as "hyaline, capitate, overtopping the spores, 

 50 — 68 x 18 — 24^i." His species was on leaves and stems of H. japonicum, ' 

 and differs slightly from the British ones. His description of the uredo- 

 sori is as follows : " Sori mostly hypophyllous, scattered or gregarious, at 

 first bright-orange, becoming pale, pulverulent, up to \ mm. diam., 

 erumpent and surrounded by the ruptured epidermis. Spores subglobose 

 to ellipsoid, finely verrucose, orange-yellow, 14 — 21x11 — 17 (i, with two 

 germ-pores on one face." On the British specimens which I have seen, 

 there are no paraphyses and the spores are decidedly in chains. 



Distribution : Europe, Siberia, India. 



14. Melampsora Lini Desm. 



Credo miniata var. Lini Pers. Syn. Fung. p. 216. 



U. Zi'm'Schum. PI. Sail. ii. 230. Arthur, N. Amer. Fl. vii. 101. 



23—2 



