. The British rust fungi (Uredinales) their biology and classification. Rust fungi -- Great Britain. ON IRIS 231 ovate, ochraceous-brown, echinulate, 20—35x16—26 jjl; epi- spore thick, with 2—4 (or more) germ-pores. Teleutospores. Sori hypophyllous, few and irregularly scat- tered, sometimes confluent, oblong, compact, persistent, soon naked, black: spores clavate or oblong, much thickened (up to 14 //,) at the summit and rounded, less often conical or truncate, gently constric- ted, usually attenuated below, smooth, fuscous-brown, darker above, 30—52x14—22yx; pedicels brown- ish, thick-walled
. The British rust fungi (Uredinales) their biology and classification. Rust fungi -- Great Britain. ON IRIS 231 ovate, ochraceous-brown, echinulate, 20—35x16—26 jjl; epi- spore thick, with 2—4 (or more) germ-pores. Teleutospores. Sori hypophyllous, few and irregularly scat- tered, sometimes confluent, oblong, compact, persistent, soon naked, black: spores clavate or oblong, much thickened (up to 14 //,) at the summit and rounded, less often conical or truncate, gently constric- ted, usually attenuated below, smooth, fuscous-brown, darker above, 30—52x14—22yx; pedicels brown- ish, thick-walled, persistent, about as long as the Fig. 178. P. Iridis. Teleuto- spores, on I. Pseudacorus. On Iris foetidissima, I. Pseuda- corus, and on many cultivated species of Iris. Not common. May—October; the teleutospores may be found on the old leaves until the following spring. (Fig. 178.) The uredo-stage is most abundant and assumes various characters, especially as regards the formation of spots ; when present these are conspicuous, oblong or oval, and yellowish, often with a greenish-brown circumference. In that case the leaf looks remarkably variegated. Plowright considered that the form which occurs on our cultivated Irises is different from that on our native species, because he could not find any teleutospores in the former ; other authors consider them as the same, because the teleutospores on many species are difficult to find, and appear only on dying leaves, especially towards the base, at the end of the season. One can easily recognise them by their being naked ; for in this species, contrary to the usual state of things, the uredo-sori remain long concealed by the epidermis and the teleuto-sori soon become uncovered. The uredospores are very thick-walled ; they can survive the winter and reproduce the fungus in the spring. This species might be hetercecious : no experimental cultures appear to have been made. It will probably turn out to possess seve
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