. The British rust fungi (Uredinales), their biology and classification. Uredineae. CRONARTIUM 315 produce the same on Vincetoxicum, Ji'emesia, Cynanchum, and Verbena., as well as on many species of Paeonia. There is reason for believing that the parasitism on Xemesia, at least, has arisen at a very recent date. This species is therefore plurivorous in its teleuto-stage, but not in its secidial stage. The mycelium is perennial, according to Fischer, in the pine- branches ; it produces secidiosiaores in May and infects the alternate hosts, on which uredo- arid teleutospores are borne during the
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. The British rust fungi (Uredinales), their biology and classification. Uredineae. CRONARTIUM 315 produce the same on Vincetoxicum, Ji'emesia, Cynanchum, and Verbena., as well as on many species of Paeonia. There is reason for believing that the parasitism on Xemesia, at least, has arisen at a very recent date. This species is therefore plurivorous in its teleuto-stage, but not in its secidial stage. The mycelium is perennial, according to Fischer, in the pine- branches ; it produces secidiosiaores in May and infects the alternate hosts, on which uredo- arid teleutospores are borne during the summer—the latter can germinate at once. 2. Cronartium Quercuum Miyabe. Uredo Quercus Brondeau in Duby, Bot. Gall. ii. 893 (1830). Cooke, Handb. p. 526; Micr. Fung. p. 216. Plowr. Ured. p. 257. Fischer, Ured. Schweiz, p. 539. Peridermium deformans and P. giganteum Tubeuf, Pflanzenkr. p. 429. Melampsora (?) Quercus Schrot. ; see Sacc. Michel, ii. 308 ; Syll. vii. 594. Cronartium asclepiadeum var. Quercuum Berk. Cli-evill. iii. 59 (from the U.S.). Sacc. Syll. vii. 597. C. Quercuum Miyabe, Bot. Mag. Tokyo, xiii. 74 (1899). C. Quercus Arthur, North Americ.-Fl. vii. 122 (1907). [zEcidiospores. -^cidia caulicolous, forming subglobose swellings 5—25 cm. across, arranged in tortuous lines or cerebroid, at first orange-yellow, bladdery; peridium col- ourless, circumscissile, soon falling away in flakes or sheets, about 2 cells thick, outer surface smooth, inner verrucose: Fi<j. -239. C. Quercuum. , , , . , . , Uredospores, on Quercus cells roundish or irregularly compressed, (ex herb. Thos. Brittain). walls very thick, lumen small; spores obovate, 25—32 x 17—23 /x ; wall colourless, uniformly thick (2|^—3i/u.), coarsely verrucose, usually with smooth spot at base and extending up one side, tubercles somewhat deciduous.] Uredospores. Sori hypophyllous, thickly scattered, round, small {I mm.), hemispherical, dehiscing by an apical pore, at length surrounded by the torn epiderm