. A text-book of mycology and plant pathology . Plant diseases; Fungi in agriculture; Plant diseases; Fungi. 188 MYCOLOGY American mycologists, pycnia (pycnium), in which spermatia, or pycniospores, are formed. Pycnia indicate the nature of the life cycle and furnish positive characters for identification. Arthur has shown that if pycnia and urediniospores are found arising from the same mycelium, ascidia do not occur in the cycle; and if pycnia and telio- spores are found there are neither uredinia nor a3cia in the life cycles. These pycnospores are accompanied or succeeded by aeciospores (ae
. A text-book of mycology and plant pathology . Plant diseases; Fungi in agriculture; Plant diseases; Fungi. 188 MYCOLOGY American mycologists, pycnia (pycnium), in which spermatia, or pycniospores, are formed. Pycnia indicate the nature of the life cycle and furnish positive characters for identification. Arthur has shown that if pycnia and urediniospores are found arising from the same mycelium, ascidia do not occur in the cycle; and if pycnia and telio- spores are found there are neither uredinia nor a3cia in the life cycles. These pycnospores are accompanied or succeeded by aeciospores (aecidiospores), which appear in the cluster cups, or aecia in long chains. The peridia of the dififerent kinds of secia are variable, and hence. Fig. 64.—Spore forms of wheat rust, Pucainia graminis. A, Section through barberry leaf showing pycnia on upper surface and aecia on lower; B, two uredinio- spores; C, germinating urcdiniospore; D, teliosorus showing several teliospores; E, single two-celledjteliospore; F, germinating teliospore with four-celled basidium and two basidiospores; G, basidiospore growing on barberry leaf. (Adapted from deBary.) mycologists have described four different kinds of form genera: Caoma = peridium absent; JEcidium = cup-shaped and peridium toothed; Rastelia = peridium elongate and fimbriate; Peridermium = peri- dium irregularly split and broken. Urediniospores (uredospores) succeed the asciospores and they appear in sori known as uredinia (uredinium). Amphispores are special forms of urediniospores formed in arid, or semi-arid climates and usually have a thick cell wall and a persistent pedicel. They are in the nature of a resting spore. Meso- spores are exactly of the same nature as the two-celled teliospores, but they arise merely by the omission of the last nuclear division, and hence,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
Size: 1546px × 1616px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1917
