. The British rust fungi (Uredinales) their biology and classification. Rust fungi. ON cyperacea; 243 ^cidiospores. ^cidia hypophyllous, crowded on red and yellow spots, roundish, also in elon- gated clusters on the young branches, petioles, and nerves, sometimes en- tirely covering the young fruits, shortly cylindrical, with broad, re- curved, white, much torn margin; spores orange, verruculose, 15—21 x 14—18yU,. Uredospores. Sori hypophyllous, punctiform, about ^ mm. long, on yellowish spots; spores more or less globose, pale-brown, echinulate, 1<S— 22 X 17—21 p., with three, rarely four,
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. ON cyperacea; 243 ^cidiospores. ^cidia hypophyllous, crowded on red and yellow spots, roundish, also in elon- gated clusters on the young branches, petioles, and nerves, sometimes en- tirely covering the young fruits, shortly cylindrical, with broad, re- curved, white, much torn margin; spores orange, verruculose, 15—21 x 14—18yU,. Uredospores. Sori hypophyllous, punctiform, about ^ mm. long, on yellowish spots; spores more or less globose, pale-brown, echinulate, 1<S— 22 X 17—21 p., with three, rarely four, germ-pores. Teleutospores. Sori amphigenous, linear or punctiform, up to 1 mm. long, pulvinate, brownish-black; spores resembling those of P. Caricis, 40—58 x 15—22 Fig. 187. P. Pringsheimiana. Leaf of Bibes Grossularia with groups of seoidia. iEcidia on Rihes Grossularia, R. nigrum (?), May and June, common; uredo- and teleutospores on G. acuta, G. caespitosa, C. Goodenovii, G. stricta. (Fig. 187.) The teleutospore-hosts are those given by Klebahn and Fischer. Klebahn first suggested the connection of the sBcidium with a Puccinia on Carex, and has since demonstrated the truth of this idea by many culture experiments. Soppitt also showed the same for Carex acuta and C. Ooode- novii. The secidium is said to attack R. alpmuin, R. aureum, R. rubrum, R. sanguineum, but less frequently. Plowright records the secidium on leaves of Ribes nignmx (Norfolk, June, 1890), but there is no proof that it belonged to this species. This species is one of those forms originally named by Klebahn P. Ribedi-Caricis ; he has since divided them under five heads which can scarcely be reckoned anything but biological races :—P. Pringsheimiana^ P. Rihis-nigri-Acutae, P. Eihis-nigri-Paniculatae, P. Pseudo-cyperi, and P. Magnusii (the latter on C. acutiformis and C. riparia). The same species of Ribes serve as alternate hosts in each case, in varying degrees of susceptibility, except
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