. The fungi which cause plant disease . Plant diseases; Fungi. 326 THE FUNGI WHICH CAUSE PLANT DISEASE In a few species "*'' ^^ there are what are known as amphispores or resting forms of urediniospores provided with thickened walls. They have colorless contents and pedicels more persistent than those of the usual urediniospore. III. Telia (teleuto-sori). Toward the latter part of the grow- ing seasons another kind of spore appears, often in the same sorus with the urediniospore and from the same mycehum. It is of various forms in different genera, one or more- celled, varies in shape, th
. The fungi which cause plant disease . Plant diseases; Fungi. 326 THE FUNGI WHICH CAUSE PLANT DISEASE In a few species "*'' ^^ there are what are known as amphispores or resting forms of urediniospores provided with thickened walls. They have colorless contents and pedicels more persistent than those of the usual urediniospore. III. Telia (teleuto-sori). Toward the latter part of the grow- ing seasons another kind of spore appears, often in the same sorus with the urediniospore and from the same mycehum. It is of various forms in different genera, one or more- celled, varies in shape, thickness of wall, surface marking, color, etc., but is uniform in the character of the germination which is very different from that of any of the other rusl^spores. In teliospore germination, tjrpically each cell of the teliospore sends forth one germ tube. These tubes soon cease growth and by septation become 4-celled. Each cell then sends out a short branch (sterigma) on which there develops one round or oval, 1-celled, thin-walled spore, the basidiospore, often in this group called the sporidium. Morphologically the promycelium is a basidium bearing its four sterigmata and four basidiospores. Relationship is thus shown on the one hand to the Ustilagi- nales, on the other hand to the Auricula- riales, an assumption that is borne out by cytological evidence. Deviations from the typical mode of germination are found in sev- eral genera mentioned belciw (e. g., Coleosporium). Basidiospores germinate immediately by germ tubes which on suitable hosts give rise again to aecia and pycnia or in some species to other spore forms completing the life cycle. The most complex life cycle is thus seen to comprise pycnio- spores, seciospores, urediniospores, teliospores and basidiospores. For brevity the first four stages are commonly designated by the following sjTnbols:. Fio. 240.—Germination of teliospores of P. asparagi. After Please note that these images are extracted from sc
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
