. The British rust fungi (Uredinales), their biology and classification. Uredineae. 140 PUCCINIA Spermogones. Fig. 92. P. Centaureae. Teleuto- sijores aud uredospore. Chiefly epiphyllous, in little clusters, orange. Sori generally hypophyllous, on yellowish or brownish spots (spots sometimes none), 2^''^'^^<^'^y rather large, secondary very minute, much scattered, pulverulent, brown; spores globose to ellipsoid, acu- leolate, brown, 22—80 x 16— 28 fi, wdth three (or two) germ- pores. Teleutospores. Sori similar, but blackish-brown; spores ellipsoid or somewhat obovate, rounde
. The British rust fungi (Uredinales), their biology and classification. Uredineae. 140 PUCCINIA Spermogones. Fig. 92. P. Centaureae. Teleuto- sijores aud uredospore. Chiefly epiphyllous, in little clusters, orange. Sori generally hypophyllous, on yellowish or brownish spots (spots sometimes none), 2^''^'^^<^'^y rather large, secondary very minute, much scattered, pulverulent, brown; spores globose to ellipsoid, acu- leolate, brown, 22—80 x 16— 28 fi, wdth three (or two) germ- pores. Teleutospores. Sori similar, but blackish-brown; spores ellipsoid or somewhat obovate, rounded at both ends, not thick- ened above, not or hardly constricted, delicately verruculose, chestnut-brown, 24—40x16—25//.; epispore thin; pedicels hyaline, thin, generally very short. On Centaurea nigra. Teleutospores, August—November. Common. (Fig. 92.) As Plowright says, there are two generations of uredospores. The primary uredospores, which are the equivalent of the aecidiospores, accom- panied by spermogones, appear in May, and are followed by the secondary uredospores, which form much smaller sori. The former, however, do not occur on every infested plant, being only produced from direct infection by the basidiospores. The primary uredospores are widely scattered by the wind ; Plowright proved that they produce the secondary spores in about fourteen days. Fischer and Jacky record this also on C. Scabiosa, but the Pucciui06 on other species of Centaurea are considered to be distinct species or else biological races. Distribution: Europe, Asia Minor, Siberia, North America. 14. Puccinia Cyani Pass. Uredo Cyani Schleich. Plant. Helv. 95. Puccinia si/aveolens var. Cyani Winter, Pilze Deutschl. p. 190. Plowr. Ured. p. 183. Sacc. Syll. vii. 633. P. Cyani Pass, in Eab. Fung. Eur. 1767. Sydow, Monogr. i. 38. Spermogones. A few mixed with the primary uredo-sori. Uredospores. Sori generally hypophyllous, without spots, scattered or crowded, minute, roundish, pulverulent, c
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