. The British rust fungi (Uredinales), their biology and classification. Uredineae. 152 PUCCINIA Uredospores. Sori hypophyllons, on pallid irregular spots, scattered, minute, punctiforra, pul- verulent, pallid-brown; spores more or less globose, eehinulate, yellow- brown, 16—24 fx, with three (rarely four) germ-pores. Teleutospores. Sori similar, surrounded by the cleft epidermis. Fig. 104. P. Chondrillae. Te- i,i„„i ; i-> u ir -j leiuospore and uredospores. blackish-brown ; spores ellipsoid, rounded and not thickened above, not constricted, rounded below, veiy delicately verruculose, brown
. The British rust fungi (Uredinales), their biology and classification. Uredineae. 152 PUCCINIA Uredospores. Sori hypophyllons, on pallid irregular spots, scattered, minute, punctiforra, pul- verulent, pallid-brown; spores more or less globose, eehinulate, yellow- brown, 16—24 fx, with three (rarely four) germ-pores. Teleutospores. Sori similar, surrounded by the cleft epidermis. Fig. 104. P. Chondrillae. Te- i,i„„i ; i-> u ir -j leiuospore and uredospores. blackish-brown ; spores ellipsoid, rounded and not thickened above, not constricted, rounded below, veiy delicately verruculose, brown, 26—36 x 16—24 /x; pedicels hyaline, very short. On Lactuca (Prenanthes) muralis only. Not common. April—September, All three spore-forms may be found on the same leaf. (Fig. 104.) The ascidiura of this species is not provided with a proper peridium and opens with a jjore, never the form of a cup ; moreover the secidiospores are more round than angular. The germ-pores of the uredo- spores are covered with a broad convex colourless cap, which swells up somewhat in water. The genetic connection of the three spore-forms has been proved experimentally by Jacky (Centralbl. f Bakt. ix. 1902, p. 842), as also the fact that the parasite is not transmissible to other species of Lactuca. There is another Eecidium also found on Lactuca muralis on the continent which possesses a well-developed peridium ; this belongs to Puccinia Opizii Bubak, and has its teleutospoVes on Carex inuricata. Distribution : Europe generally. 27. Puccinia variabilis Grev. jEcidium Grevillei Grove, Journ. Bot. 1886, p. 129. Pihccinia variabilis Grev. Scot. Crypt. Fl. pi. 75. Cooke, Handb. p. 500 ; Micr. Fung. p. 207, pi. 4, f. 82—3. Plowr. Ured. p. 150. Sydow, Monogr. i. 163. Fischer, Ured. Schweiz, p. 202, f. 158. jEcidiospores. /Ecidia amphigenous, on minute indetermi- nate yellow or purplish spots, solitary or a few loosely aggre- gated, cup-shaped, with whitish torn margin; spores sub
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