. The fungi which cause plant disease . Plant diseases; Fungi. 318 THE FUNGI WHICH CAUSE PLANT DISEASE Urocystis Rabenhorst"' (p. 314) Sori usually in the leaves or stems, occasionally in other parts, producing dark-colored, usually dusty, spore-masses; spore-balls permanent, composed of an enveloping cortex of tinted sterile cells and usually one to Fig. 233.—Spore several interior fertile cells; fertile cells generally balls of U. ce- , , , , . ,. , , puia5. After dark-colored; germmation often by a short promyce- Thaxter. jj^^^ ^^^^^ ^^.^ duces terminally-grouped spori- dia; these give
. The fungi which cause plant disease . Plant diseases; Fungi. 318 THE FUNGI WHICH CAUSE PLANT DISEASE Urocystis Rabenhorst"' (p. 314) Sori usually in the leaves or stems, occasionally in other parts, producing dark-colored, usually dusty, spore-masses; spore-balls permanent, composed of an enveloping cortex of tinted sterile cells and usually one to Fig. 233.—Spore several interior fertile cells; fertile cells generally balls of U. ce- , , , , . ,. , , puia5. After dark-colored; germmation often by a short promyce- Thaxter. jj^^^ ^^^^^ ^^.^ duces terminally-grouped spori- dia; these give rise to similar secondary sporidia or to infec- tion-threads. Besides the forms discussed below, foreign species are listed on Anemone, Liliacese, Gladiolus, Primula, etc. U. cepulae Frost.^'' ^ "»' i^« Sori in leaves, forming isolated pustules or affecting them for the greater part of their length and breadth, sometimes occur- ring at their bases, in the bulbs. Upon rupture of the covering membrane a dusty black-brown spore-mass appears; spore-balls ovoid to spherical, 17-25 n in length; sterile cells tinted, ovoid to spherical, small, rather com- pletely covering the spores, usually 4r-8 n in length; fertile cells reddish-brown, ovoid to spherical, usually 1, rarely 2 in a ball, chiefly 12-16 ju in length. On Allium. The first American description of the fungus was by Farlow ^ in 1876. A second thorough paper was from Thaxter in 1889.** The myedium grows between the host cells. At maturity lateral. Fig. 234.—Spores of U. cepulte genni- nating. x, sporidia; 23, geriuinating conidium. After Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Stevens, Frank Lincoln, 1871-1934. New York : Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
