. The fungi which cause plant disease . Plant diseases; Fungi. 324 THE FUNGI WHICH CAUSE PLANT DISEASE verrucosely sculptured, borne singly, or sometimes in chains, (5) teliospores, smooth or variously sculptured but not echinulate, borne singly or in chains. In every species the mycelium even- tually gives rise to teliospores, which produce in germination four basidia, either remaining within the spore-cell or borne in the air on a short promycelium, each basidium supporting a single, stalked or sessile basidiospore. The order of some two thousand species, constituting the "rust" fu
. The fungi which cause plant disease . Plant diseases; Fungi. 324 THE FUNGI WHICH CAUSE PLANT DISEASE verrucosely sculptured, borne singly, or sometimes in chains, (5) teliospores, smooth or variously sculptured but not echinulate, borne singly or in chains. In every species the mycelium even- tually gives rise to teliospores, which produce in germination four basidia, either remaining within the spore-cell or borne in the air on a short promycelium, each basidium supporting a single, stalked or sessile basidiospore. The order of some two thousand species, constituting the "rust" fungi, many of them living on cultivated plants of high value, is of great economic significance. Its members are strict, obUgate, parasites which in no stage of the life except in the promycelial stage can develop other than on the living host. The complexities of the life histories of the species, with their five distinct spore forms, inhabiting at different seasonal periods two or even three different host plants, renders the order both difficult and exceedingly in- teresting. The hfe history of the most complete of these fungi may be stated as follows: I. .£cia (secidia) and O. pycnia (often called spermo- gonia or pycnidia). The my- celium arising from a basidio- spore invades the host plant, and vegetates until vigor suf- ficient to spore formation is attained, meantime often pro- ducing local spotting, hyper- trophy, or other injury to the host. The mycelium then de- velops a stroma which pro- duces spore beds (son) and ruptures the epidermis. These sori are usually deeply sunken in the host and cup-shaped and take the common name "cluster cups," Fig. 239, technically secia or aecidia. The sporophores arise from a hyphal plexus at the base of the cup and the spores are borne catenulate in acropetal suc-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
