. Contributions from the Botanical Laboratory, vol. 5. Botany; Botany. Fig. 2. Longitudinal sections (X300) of epidermal cells of root tip. 1. C. maculata 2. P. rotundifolia Y _ free hyphal filaments, S = sheath. separated by a pseudoparenchyma, much like that seen in Monotropa. There is apparently no invasion of any layer beneath the epidermis. Kramar (44) has described all stages of the growth of the mycorhiza. The walls of the epidermal cells first become infested with hyphae forming a pseudoparen- chyma between the cells. Later, when the epidermal cells become full size the hyphae penetrat
. Contributions from the Botanical Laboratory, vol. 5. Botany; Botany. Fig. 2. Longitudinal sections (X300) of epidermal cells of root tip. 1. C. maculata 2. P. rotundifolia Y _ free hyphal filaments, S = sheath. separated by a pseudoparenchyma, much like that seen in Monotropa. There is apparently no invasion of any layer beneath the epidermis. Kramar (44) has described all stages of the growth of the mycorhiza. The walls of the epidermal cells first become infested with hyphae forming a pseudoparen- chyma between the cells. Later, when the epidermal cells become full size the hyphae penetrate the cell wall, make direct for the nucleus and begin to form a ball around it. The nucleus finally becomes hypertrophied and lifeless. When this occurs and the cell is packed full of hyphae they penetrate the cell wall again and spread out over the surface. Before this occurs r i' Kramar says that the fungus is only a parasite drawing its nourishment from the plant. After the outer covering is formed, however, the fungus can then take the place of root hairs and absorb water for the plant. It may also give a part of its own assimilated food to the plant. Frank observes that as the fungus dies each year the plant could then absorb its protein content. Kramar also describes the contents of the subepi- dermal cells, that they are coarsely granular and that these cells represent a storage place where the nutritive material, taken in by the mycelium, lies until ready to be transferred to where it is to be used. He probably saw the starch grains similar in appearance to those of Chimaphila when they had become disintegrated to the extent of not showing a hilum. Pyrola elliptica has practically the same appearance as P. rotundifolia. P. secunda is reported to have fungal hyphae by Irmisch (32), Rommel (65), Andres (2), Petersen (60); P. minor by Kramar (44) and Petersen (60). P. aphylla is described by Holm (30) as having the root free from hyphae. This seems rather improbable in vi
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