. Plant studies; an elementary botany. Botany. 274 PLANT STUDIES dew, Microsphcera, grows on lilac leaves, which nearly al- ways show the whitish covering after maturity (Fig. 241). The branching hyphae show numerous partition walls, and are not coanocytic as in the Phycomycetes. Small disk-like haustoria penetrate into the superficial cells of the host, anchoring the mycelium and absorbing the cell contents. Sporophores arise, which form asexual spores in a pe- culiar way. The end of the sporophore rounds off, almost separating itself from the part below, and becomes a spore or spore-like bod
. Plant studies; an elementary botany. Botany. 274 PLANT STUDIES dew, Microsphcera, grows on lilac leaves, which nearly al- ways show the whitish covering after maturity (Fig. 241). The branching hyphae show numerous partition walls, and are not coanocytic as in the Phycomycetes. Small disk-like haustoria penetrate into the superficial cells of the host, anchoring the mycelium and absorbing the cell contents. Sporophores arise, which form asexual spores in a pe- culiar way. The end of the sporophore rounds off, almost separating itself from the part below, and becomes a spore or spore-like body. Below this another organizes in the same way, then another, until a chain of spores is developed, easily broken apart and scat- tered by the wind. Falling upon other suitable leaves, they germinate and form new mycelia, enabling the fungus to spread rapidly. This meth- od of cutting a branch into sections to form spores is called abstriction, and the spores formed in this way are called conidia, or conidi- ospores (Fig. 243, B). At certain times the myce- lium develops special branches which develop sex organs, but they are seldom seen and may not always occur. An oogo- nium and an antheridium, of the usual forms, but probably without organizing gametes, come into contact, and as a result an elaborate structure is developed—the ascocarp, sometimes called the "spore ; These ascocarps ap- pear on the lilac leaves as minute dark dots, each one being. Fig. 241. Lilac leaf covered with mil- dew (Micro&pkazra), the shaded re- gions representing the mycelium, and the black dote the ascocarps.— S. M. 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 Coulter, John Merle, 1851-1928. New York, D. Appleton and Company
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