. Contributions from the Botanical Laboratory, vol. 5. Botany; Botany. 6o Henderson—Comparative Study of Pyrolaceae and spora. It is coated with a dense brownish septate mycelium which pushes in between the epidermal cells, penetrates them, forming irregular vesicles and distorted nuclei, and even enters the sub-epidermal layers. A root cap is present, and MacDougal states that this resembles that of Sarcodes, in having more than two layers. The mycelium covers the root cap and penetrates the older cells in free tips, but penetrates beneath the root cap in those roots that are in the center of
. Contributions from the Botanical Laboratory, vol. 5. Botany; Botany. 6o Henderson—Comparative Study of Pyrolaceae and spora. It is coated with a dense brownish septate mycelium which pushes in between the epidermal cells, penetrates them, forming irregular vesicles and distorted nuclei, and even enters the sub-epidermal layers. A root cap is present, and MacDougal states that this resembles that of Sarcodes, in having more than two layers. The mycelium covers the root cap and penetrates the older cells in free tips, but penetrates beneath the root cap in those roots that are in the center of the clump. He states that starch is present in the outer cortical layers and that sec- ondary roots arise exogenously. Thus in the root tip region we have a gradually ascending series in the amount of fungus present from C. umbellata, with the epidermal cells of some roots with no hyphae—other roots with hyphae, but not in every cell; to C. maculata with a still greater number of the epidermal cells filled with hyphae; to P. rotundifolia and P. elliptica with all of the cells infested and with a beginning of a sheath of intertwined hyphae around the root tip; then in M. hypopitys an increase in the width and extent of this sheath and a division of it into two zones—the outer a more loosely interwoven mass of hyphae, the inner more compact; finally in M. uniflora a still greater width of the fungal sheath. The descriptions of the presence of hyphae in Sarcodes and Pterospora show a great resemblance to Mono- tropa, but not having material to examine the writer cannot say which has the larger amount of mycelial investment. In ChimapUla the hyphae are probably not of much use to the plant as the threads are only in the epidermal cells and do not extend out over the surface. The development of an outer sheath of hyphae in Pyrola and its great increase in amount in Monotropa, Sarcodes, and Pterospora would allow the fungus to be of more use to the plant and that this is true
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