. Nature and development of plants. Botany. 252 DEVELOPMENT OF A RUST bodies which rupture the epidermis and finally open out into cups filled with chains of yellowish spores. An examination of Fig. 162 shows that these spores are formed in rows at the end of hyphae and surrounded by a layer of rather thick-walled hyphae. This stage of the rust is known as the cluster cup or aecial stage and the spores are called aeciospores. Often smaller spore-bear-. FiG. 162. Cluster cups as seen in section of leaf of spring beauty, Clay- tonia. At right one of the cups is ruptured, exposing the aeciospores
. Nature and development of plants. Botany. 252 DEVELOPMENT OF A RUST bodies which rupture the epidermis and finally open out into cups filled with chains of yellowish spores. An examination of Fig. 162 shows that these spores are formed in rows at the end of hyphae and surrounded by a layer of rather thick-walled hyphae. This stage of the rust is known as the cluster cup or aecial stage and the spores are called aeciospores. Often smaller spore-bear-. FiG. 162. Cluster cups as seen in section of leaf of spring beauty, Clay- tonia. At right one of the cups is ruptured, exposing the aeciospores. Below a small cup, pycnium, is discharging pycniospores that are possibly functionless male gametes. ing cups, known as pycnia (sing, pycnium), are associated with this phase of the fungus. These small spores, while capable of germinating, do not appear to enter into the life history of the fungus by producing a new parasite. They have been looked upon as male gametes that originally effected fertilization in a female organ from which developed the spore-bearing cluster cup, the process being similar to that noted in the Red Algae. On the other hand they are regarded by some authorities as spores that have lost their power to germinate and so breed the fungus asexually. The process of spore formation in the cluster cup, as will be seen from the outline given below, is so different from that of the algae and is known in so few forms that any interpre- tation of the phenomena should be deferred for 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 Curtis, Carlton Clarence, 1864-1945. New York, H. Holt
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