. Comparative morphology of Fungi. Fungi. UREDINALES 579 In another direction, Uromycladium and Ravenelia have been dif- ferentiated. In the simpler forms, as Uromycladium simplex (McAlpine, 1905), there arises at each terminal cell a teliospore deceptively similar in form and structure to Uromyces (Fig. 389, 9). The basal cell changes into a double-walled, hyaline cyst c filled with a gel capable of swelling (a characteristic of both genera). Exceptionally, the cysts may be absent and replaced by a second teliospore. In other forms, , U. bisporum,. Fig. 392.—Ravenelia cassiaecola. A. Infe
. Comparative morphology of Fungi. Fungi. UREDINALES 579 In another direction, Uromycladium and Ravenelia have been dif- ferentiated. In the simpler forms, as Uromycladium simplex (McAlpine, 1905), there arises at each terminal cell a teliospore deceptively similar in form and structure to Uromyces (Fig. 389, 9). The basal cell changes into a double-walled, hyaline cyst c filled with a gel capable of swelling (a characteristic of both genera). Exceptionally, the cysts may be absent and replaced by a second teliospore. In other forms, , U. bisporum,. Fig. 392.—Ravenelia cassiaecola. A. Infected twig of Cassia nictitans, with telium on stem and uredinium on leaf. B. Enlarged section of stem. C. Section through periphery of telium on stem. The cuticle is ruptured. Mycelium visible in the cells of the bark. Telium shows mature and young heads, one in cross section. Ravenelia appendiculata. D. Head seen from above. E. Isolated spore. (A, natural size; B X 10; C X 350; D, E X 400; after Dietel, 1906.) the sporiferous hyphae regularly produce two teliospores without cysts. Still others, as U. maritimum, develop two teliospores (Fig. 389, 6 and 7) above a third cell from which a cyst is developed; here also, in an excep- tional case, the cyst may be replaced by a third teliospore. And finally in the highest forms, , U. Tepperianum, three teliospores without cysts are regularly formed on the stipe cells. In Ravenelia (Fig. 392), a very significant development of spore heads appears (Parker, 1887; Dietel, 1906). The first fundament of the heads. 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 Gäumann, Ernst Albert, 1893-1963; Dodge, Carroll William, 1895-. New York [etc. ] McGraw-Hill Book Company, Inc.
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