. The British rust fungi (Uredinales) their biology and classification. Rust fungi -- Great Britain. 132 PUCCINI \. Pig. 83. P. Chry- santhemi. Ure- dospore (Brit- ish). Uredospores. Sori generally hypophyllous, on irregular pallid-yellow or brownish spots, scattered or in clusters, about 1—1! nun. diam. often circi- oate, pulverulent, snuff-brown; spores globose to ellipsoid, delicately echinulate, brown, 24— •">2 x 17—27p, mostly with three germ-pores. [Teleutospores. Mixed with the undospores, oblong or ellipsoid, rounded and slightly thickened above, usually rounded or some- what t
. The British rust fungi (Uredinales) their biology and classification. Rust fungi -- Great Britain. 132 PUCCINI \. Pig. 83. P. Chry- santhemi. Ure- dospore (Brit- ish). Uredospores. Sori generally hypophyllous, on irregular pallid-yellow or brownish spots, scattered or in clusters, about 1—1! nun. diam. often circi- oate, pulverulent, snuff-brown; spores globose to ellipsoid, delicately echinulate, brown, 24— •">2 x 17—27p, mostly with three germ-pores. [Teleutospores. Mixed with the undospores, oblong or ellipsoid, rounded and slightly thickened above, usually rounded or some- what tapering at base, scarcely constricted, delicately verruculose, chestnut-brown, 35—57 x 20—25 fi: pedicels thick, hyaline, persistent, 35—60[i long; mesospores subglobose or pyriform, slightly thickened at the summit, 32—37 x 20—21 fi.] On leaves of Chrysanthemum in- dicum and C. sinense (not on other species of the genus, much less on other genera of Compositae), in greenhouses, all the year round. The leaves that are attacked soon flag and die. (Figs. 83, 84.) This species is said to be very common in Japan. It was first observed in England in 1895, and has been found in other Euro- pean countries and in North America ; in 1904 it reached Australia and New Zealand. In Japan it produces teleutospores in separate sori, which are hypophyllous, roundish, dark-brown and naked, but in Europe the teleutospores have been rarely seen, though mesospores occasionally occur. Abnormal and 2-celled uredospores (as well as 3- or 4-celled teleutospores) have been described and figured by Roze, Jacky and Eischer ; but these I have not seen in British specimens. Since, under the conditions in which the plants are grown here, the young shoots appear above ground before the old ones die away, it is probable that the parasite maintains itself by the uredospores alone; the alternative would be the possession of a perennial mycelium, which has not. Please note that these images are
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