. A manual of botany. Botany. 88 MANUAL OF BOTANY trated by an incompletely septate mycelium. Dm-ing the summer this mycelium produces patches of gonidia, each borne upon a short stalk. These develop underneath the epidermis of the host, and, being of a yellow or reddish colour, give the part a rusty appearance. These are known as uredospores or uredogonidia. These escape by rupture of the epidermis {fig. 849, a), and are blown upon other grass plants, where they ger- minate, and the hypha penetrates the host through a stoma. In the interior a mycehum is produced, which again produces patches
. A manual of botany. Botany. 88 MANUAL OF BOTANY trated by an incompletely septate mycelium. Dm-ing the summer this mycelium produces patches of gonidia, each borne upon a short stalk. These develop underneath the epidermis of the host, and, being of a yellow or reddish colour, give the part a rusty appearance. These are known as uredospores or uredogonidia. These escape by rupture of the epidermis {fig. 849, a), and are blown upon other grass plants, where they ger- minate, and the hypha penetrates the host through a stoma. In the interior a mycehum is produced, which again produces patches of uredospores. Towards the end of the summer the same mycehum gives Fig. 849. Fig. Fig. 849. A. Grass leaf infested with Fuccinia graminis^ showing the uredo- spores bursting through the epidermis of tiie leaf. E. Teleutospore ger- minating and producing promycelium with sporidia. Fig. 850. Teleuto- spores of Fuccinia graminis bursting through epidermis of straw. After Kny. origin to black patches which are visible upon the straw. These are composed of numbers of compound gonidia, two together upon a single stalk, developed as before by abstriction {fig. 850). These, which are called teleutospores, or teleutogonidia, have thick black walls and are very resistant. They remain quiescent tin the spring, when one or both of the cells germinates, produ- cing a small promycehum, usually of four cells. Each cell puts out a small gonidiophore, from which a small gonidium, called a sporidium, is developed by abstriction {fig. 849, b). From a re- semblance to the cells which abstrict the spores in the next group, these cells are sometimes called proto-hasidia. The sporidium is a very small thin-waUed structure, and from its lightness it is. 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 Green, J. Reynolds (Jos
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
