. The British rust fungi (Uredinales), their biology and classification. Uredineae. CRONARTIUM 317 Teleutospores. Columns hypophyllous, cylindrical, curved, up to 2 mm. long, crowded especially along the veins of the leaf, sometimes covering the whole leaf, orange to brownish- yellow ; spores oblong, smooth, reaching 70/z long x 21 /x broad. JEcidia on stems and branches of Piims Ceinbra, P. monti- cola, P. Strohus, March—June; uredo- and teleutospores on Kibes nigr-um, P. ruhrum, etc., July—October. Uncommon except when imported; Surrey, King's Lynn, Exeter, West- burv, Woburn, Windsor Forest
. The British rust fungi (Uredinales), their biology and classification. Uredineae. CRONARTIUM 317 Teleutospores. Columns hypophyllous, cylindrical, curved, up to 2 mm. long, crowded especially along the veins of the leaf, sometimes covering the whole leaf, orange to brownish- yellow ; spores oblong, smooth, reaching 70/z long x 21 /x broad. JEcidia on stems and branches of Piims Ceinbra, P. monti- cola, P. Strohus, March—June; uredo- and teleutospores on Kibes nigr-um, P. ruhrum, etc., July—October. Uncommon except when imported; Surrey, King's Lynn, Exeter, West- burv, Woburn, Windsor Forest, Perth, etc. (Fig. 240.). Fig. 240. C. ribicola. a, spore of Perldermium Strubi; b, the teleutospore- columus on leaf of Bed Currant (reduced); c, uredospore; d, top of a column of teleutospores, x 600. This dangerous parasite, sometimes called the Weymouth Pine Eust, is confined in its secidial stage to the five-leaved Pines ; it is reported on the continent also on P. excelsa and P. Lamhertiana. The secidiospore is distinguished from that 'of Peridermium Pini and P. Cornui by the fact that a great part of the surface is smooth. The attacked trees are stunted, the tops show a bushy growth that can easily be recognised; the part where the mycelium is growing is swollen. In the Currant, the attacked leaves become thicker in texture, and different in colour. It was first discovered, in this country, at King's Lynn by Dr Plow- right, who found the Cronartmm on leaves of blacky white, and red currant on July 3, 1892. On Aiigust 13 he exhibited in London a branch of P. Strohus affected by the mycelium of the alternate stage; the tree grew about fifteen yai-ds away from the cun-ant bushes. On March 19, 1893, he found the Peridermium in full perfection at the same place. Though the aecidium occurs in Europe chiefly on the "Weymouth Pine {P. Strohus), yet that cannot be its original host, since neither Cronartium ribicola nor Peridermium Strohi was found in America (the home
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