. The British rust fungi (Uredinales) their biology and classification. Rust fungi. GYMNOSPOEANGIDM 309 j^cidiospores. ^cidia hypophyllous, on the same spots, flask shaped, 1—2 mm. broad, pale-brown, split to the base into lacinise which remain united at the summit, and at first are joined at intervals by short transverse bands; spores finely verru- culose, brown, 28—30 fj. (average). Teleutospores. Spore-masses on the branches, at first pulvinate, dark- brown, then irregularly conical, 8—• 10 mm. high, red-brown, gelatinous; spores of two kinds, thick-walled and thin-walled, broadly and obtus
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. GYMNOSPOEANGIDM 309 j^cidiospores. ^cidia hypophyllous, on the same spots, flask shaped, 1—2 mm. broad, pale-brown, split to the base into lacinise which remain united at the summit, and at first are joined at intervals by short transverse bands; spores finely verru- culose, brown, 28—30 fj. (average). Teleutospores. Spore-masses on the branches, at first pulvinate, dark- brown, then irregularly conical, 8—• 10 mm. high, red-brown, gelatinous; spores of two kinds, thick-walled and thin-walled, broadly and obtusely bi- conical, scarcely constricted, smooth, brown, 40—50 x 25—30 fi; germ-pores four, two in each cell. ^cidia on Pyrus communis, July— September; teleutospores on Juniperus Sabina, April and May. Not Fig. 234. Groups of secidia on leaf of Pear. xi. (Fig. 234.) This is said to occur on other species of Pyrus and Juniperus. The life-history is similar to that of the other Gymnosporangia. The spermo- gones are said by Fischer to have occurred on the fruit of the Pear ; other authors record the secidia on both the young fruits and the petioles. The secidia are easily distinguishable from all the others, the upper part of the peridium, after dehiscence, looking very like the calyptra oi Polytriohum; but the teleutospores are similar to those of O. confusum, the chief diflference being that the thick-walled spores of the latter are rounded at the summit, not bluntly conical. In this, as in all the similar cases, when the secidium is found on its host, search should be made in the neighbourhood for the alternate host ; the Juniper is often found in a neighbouring garden. Since it is. always the teleutospore-mycelium that is perennial, the only successful remedy for this plant-disease is to destroy and burn the Juniper, or at least the affected part; it is useless to spray the tecidial host. Distribution: Please note that these images ar
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