. The British rust fungi (Uredinales) their biology and classification. Rust fungi. ON VIOLA 203 On Viola cornuta, V. lutea, V. tricolor, and most of the many hybrid Violas and Pansies now cultivated in gardens. Fresh aecidia are formed right through the summer till August, while those of P. Violae cannot usually be found after early June. (Fig. 150.) The mycelium of the secidia is perennial in the underground parts ; all the shoots which arise from the affected plant are deformed, the internodes are lengthened, the leaves become smaller, paler and often twisted. In P. Violae this is not the c
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. ON VIOLA 203 On Viola cornuta, V. lutea, V. tricolor, and most of the many hybrid Violas and Pansies now cultivated in gardens. Fresh aecidia are formed right through the summer till August, while those of P. Violae cannot usually be found after early June. (Fig. 150.) The mycelium of the secidia is perennial in the underground parts ; all the shoots which arise from the affected plant are deformed, the internodes are lengthened, the leaves become smaller, paler and often twisted. In P. Violae this is not the case ; only a slight swelling arises at the part where the localised mycelium is producing its iecidia. Bock (Centralbl. fiir Bakt. 2. xx. 586) found that he could produce the secidia of P. Violae on the three species of Viola named above, by artificial infection ; but like others he still considered the two species as distinct on account of their different habit. Liro, on the contrary, considers them as the same. In my experience, the uredo- and teleuto-sori of P. aegra are larger, and remain longer covered by the epidermis, but the spores are identical. This species can do considerable harm if allowed to spread ; there is no remedy, but all infected plants should be carefully uprooted and burnt. A Viola, badly attacked by the secidium, was once sent to the Gardener's Chronicle by a correspondent as " a hybrid between a fern and a violet.'' Distribution : Germany, Denmark. 75. Puccinia Fergussoni B. et Br. Puccinia Fergussoni Berk, et Br. Ann. Nat. Hist. 1875, p. 35. Cooke, Grevillea, iii. 179, pi. 49, f. 10 c ; Micr. Fung. p. 210. Plowr. Ured. p. 207. Sacc. Syll. vii. 682. Sydow, Monogr. i. 444. Grove, Journ. Bot. 1912, p. 10. Teleutospores. Sori hypophyllous or on the petioles, on large roundish or irregular yellow spots, in suborbicular or (on the petioles) elon- gated clusters up to 1| cm. long, densely crowded and confluent, long covered by the epidermis, then pulveru
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