. Botany for agricultural students . Botany. 374 THALLOPHYTES haustoria are sent into the host. These haustoria absorb food from the tissues, and often cause considerable injury to the leaves and fruit. From the superficial hyphae arise numerous erect conidio- phores, which pioduce chains of conidiospores (Fig. 324). The powdery appearance of the Fungus is due to the ascocarps and the numerous conidiospores. The conidiospores are distributed by the wind and, when favorably placed, grow directly into hyphae, and are the means of producing new growths of the Mildew. Late in the summer and autumn
. Botany for agricultural students . Botany. 374 THALLOPHYTES haustoria are sent into the host. These haustoria absorb food from the tissues, and often cause considerable injury to the leaves and fruit. From the superficial hyphae arise numerous erect conidio- phores, which pioduce chains of conidiospores (Fig. 324). The powdery appearance of the Fungus is due to the ascocarps and the numerous conidiospores. The conidiospores are distributed by the wind and, when favorably placed, grow directly into hyphae, and are the means of producing new growths of the Mildew. Late in the summer and autumn, the superficial hyphae form. ^-V'i^ H Fig. 325. — At the left, surface of a leaf infected with Powdery Mildew, showing the superficial mycelium, ascocarps, and conidiophores. At the right, a cleistothecium broken open, showing the asci which develop within. From Tulasne and Nature. globular heavy-walled cleistothecia in which the asci are produced and which, when mature, appear to the naked eye as black dots on the surface of the leaf {Fig. 325). Projecting from the wall of the ascocarp are appendages which may have variously branched tips. Enclosed within the heavy wall of the ascocarp, the ascospores pass the winter. When freed in the spring by the breaking of the ascocarp, the spores may be blown or carried about and germinate upon a new host. The development of the ascocarp is a result of fertilization and the sex organs, like those of Pyronema, suggest those of the Red Algae. The ascocarp of the Mildews suggests the cystocarp of the. 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 Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
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