. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. VIII] UREDINALES 207. Fig. 183. Coleosporium Son- chi ; uredosorus, x 545 ; after Holden and Harper. group of basal cells of indefinite extent, from which the aecidiospore mother- cells are cut off The aecidium is, in fact, no more a definite organ than the uredo- or teleutosorus, and only appears so in the more elaborate forms because of the modification of its peripheral cells to form a pseudoperidium. The important distinction lies not in the general morpho- logy of the sorus, but in the fact that an association of two nuclei from diff
. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. VIII] UREDINALES 207. Fig. 183. Coleosporium Son- chi ; uredosorus, x 545 ; after Holden and Harper. group of basal cells of indefinite extent, from which the aecidiospore mother- cells are cut off The aecidium is, in fact, no more a definite organ than the uredo- or teleutosorus, and only appears so in the more elaborate forms because of the modification of its peripheral cells to form a pseudoperidium. The important distinction lies not in the general morpho- logy of the sorus, but in the fact that an association of two nuclei from different cells takes place in the basal cell of the aecidium and in the specialization indicated by the separation of the sterile cells. In its general structure the spermogonium, con- sisting as it does of a series of spermatial hyphae with or without circumjacent paraphyses, is not very different from the other sori, and, in the simplest cases, it also is of indefinite extent. Omission of Spore Forms. In many rusts one or more spore forms are omitted; the case where the so-called primary uredospore is substituted for the typical aecidiospore has been already described; these and others in which the characteristic aecidium or caeoma alone is lacking are distinguished by the prefix brachy. Hemi- indicates the presence of uredo- and teleutospores without aecidia or spermogonia. The suffix opsis is used for forms with aecidia and teleutosori. They lack uredosori but a few uredospores are sometimes found in the teleutosorus. Micro- and lepto- forms have teleutospores with a few occasional uredospores and sometimes spermogonia. The teleutospores germinate in the former group only after a period of rest, in the latter upon the same host plant as soon as they reach maturity. Species with the full complement of spores are distinguished by the prefix eu. As already pointed out, the sporophyte in some of the brachy- species starts from the fertile cells at the base of the so-called uredoso
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
