. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 136 PUCCINIA Formerly united with Pucdnia Absinthii, from which it is distinguished by its (on the average) narrower and shorter teleutospores, with longer pedicels. I could not see in any case that the teleutospores were verru- culose, as they are said to be. Distribution : North-western and Central Europe. 8. Puccinia expansa Link. Pucdnia expansa Link, Sp. PI. vi. 2, p. 75. Sydow, Monogr. i. 146. Fischer, Ured. Schweiz, p. 182, f. 141—2. P. Senecionis Cooke, Micr. Fung. p. 207. Plowr. Ured. p. 209, (non Lib.
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 136 PUCCINIA Formerly united with Pucdnia Absinthii, from which it is distinguished by its (on the average) narrower and shorter teleutospores, with longer pedicels. I could not see in any case that the teleutospores were verru- culose, as they are said to be. Distribution : North-western and Central Europe. 8. Puccinia expansa Link. Pucdnia expansa Link, Sp. PI. vi. 2, p. 75. Sydow, Monogr. i. 146. Fischer, Ured. Schweiz, p. 182, f. 141—2. P. Senecionis Cooke, Micr. Fung. p. 207. Plowr. Ured. p. 209, (non Lib.). Teleutospores. Sori amphigenous,but generally hjrpophyllous, on round yellowish or brownish spots, densely crowded and con- fluent in roundish clusters 5—8 mm. broad, blackish-brown; spores ovate or broadly ellipsoid, rounded at both ends, with a minute paler ^. „„ „ mix apical papilla, hardly constricted, Fig. 88. P., expansa. Teleuto- r r r ' J ' spores and mesospore, on S. smooth, brown, 30—40x19—30/i, """ '^°" but sometimes smaller; pedicels hyaline, very short; an occasional mesospore is seen. On Senecio aquaticus, S. Jacobaea. Not common. July— September. (Fig. 88.) The sori of this species are chiefly on the underside of the leaf; they are collected into roundish or elongated groups and open by a small round pore, after the manner of some secidia, so that, when the spores have fallen out, the group looks like a honeycomb. P. glomerata is said to be distinguished by its paler, narrower and longer spores with a smaller papilla, and by having the sori on both leaf-surfaces. I think the two species are the same so far as our specimens are concerned, but have followed Sydows' Monographia pro tern. Plowright has confused the characters of the two, partly because he thought his species on S. aquaticus was P. Senecionis Lib., which is incorrect. The true P. Senecionis Lib. has not been found in Britain. Distribution : Central Europe, Holla
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