. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 154 PUCCINIA 28. Puccinia Taraxaci P],owr. Puccinia Phaseoli var. Taraxaci Eebent. Fl. Neomaroh. p. 356. P. variabilis Grev. ; Cooke, Handb. p. 500; Micr. Fung. p. 207 P. Taraxaci Plowr. Ured. p. 186. Sacc. Syll. ix. 305. Sydow, Monogr. i. 164. Fischer, Ured. Schweiz, p. 226, f. 178. Spermogones. In little yellow roundish clusters. Vredospores. Sori amphigenous, with or without spots, scattered, minute, sometimes confluent and larger, roundish or oblong, pulverulent, brown; spores glo- bose to ovate, echin
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 154 PUCCINIA 28. Puccinia Taraxaci P],owr. Puccinia Phaseoli var. Taraxaci Eebent. Fl. Neomaroh. p. 356. P. variabilis Grev. ; Cooke, Handb. p. 500; Micr. Fung. p. 207 P. Taraxaci Plowr. Ured. p. 186. Sacc. Syll. ix. 305. Sydow, Monogr. i. 164. Fischer, Ured. Schweiz, p. 226, f. 178. Spermogones. In little yellow roundish clusters. Vredospores. Sori amphigenous, with or without spots, scattered, minute, sometimes confluent and larger, roundish or oblong, pulverulent, brown; spores glo- bose to ovate, echinulate, pale-brown, 22—27 X 16—24 yu,, with two germ-pores. Teleutospores. Sori similar, but blackish, ^—| mm. diam.; spores ellip- Fig 106. P. Taraxaci. ^"^^ *° ovate, rounded at both ends, not Teleutospore and uredo- thickened above, not constricted, very delicately verruculose, brown, 25—38 x 16—24/x; epispore thin; pedicels hyaline, short. On Taraxacum officinale. Rather common. Spermogones and primary uredospores in April; the teleutospores may be found till November. The distinctions which Plowright attempts to draw between the primary and secondary uredospores are not so marked as is the case in P. Centaureae, and break down in practice. (Fig. 106.) This species differs from P. variabilis, with which it was formerly confused, chiefly in the absence of the secidium. But, in addition to that, the uredospores of P. Taraxaci are far more abundant and the sori more especially found on the upper leaf-surface; the uredospores of P. variabilis are scanty and are usually intermixed in the teleuto-sori. P. Taraxaci is morphologically indistinguishable from P. Biei'acii, but culture experi- ments have proved that it cannot be transferred from Taraxacum to the alHed genera of the Oompositas. Plowright's remark {I. c. p. 187) that I considered this species to have "a true secidium" is a mistake, arising probably from a confusion between it and P. variabilis.
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