. Introduction to botany. Botany. Mosses, Ferns, and Horsetails. 301 The sporangia split open after the manner of anthers and the spores are readily shaken out by the wind. The spore is peculiar in having its outer coat split into four ribbon-hke bands which coil and uncoil with the varying humidity of the atmos- phere. On dry- ing, the bands uncoil, and on imbibing mois- ture they coil up again. Perhaps the coiled bands, when they come in contact with a suitable object, may serve to an- chor the spores in a moist place where the con- ditions for ger- mination are good ; or in dry situations,
. Introduction to botany. Botany. Mosses, Ferns, and Horsetails. 301 The sporangia split open after the manner of anthers and the spores are readily shaken out by the wind. The spore is peculiar in having its outer coat split into four ribbon-hke bands which coil and uncoil with the varying humidity of the atmos- phere. On dry- ing, the bands uncoil, and on imbibing mois- ture they coil up again. Perhaps the coiled bands, when they come in contact with a suitable object, may serve to an- chor the spores in a moist place where the con- ditions for ger- mination are good ; or in dry situations, where the bands are spread out, they may serve as sails to catch the wind so that the spores may be carried to more favorable situations. The bands may also prove useful in binding several spores together; for since the spores on germinating give rise to prothalha bearing only eggs or sperms, the prothallia being dioecious, it would be obviously in the interest of the fertilization. Fig. 160. Equisetum an'ens€. C, a sterile shoot; D, fertile shoots; o and /, clusters of sporangia; q and r, sporophylls bearing sporangia; s, t, and u, spores, with spiral bands uncoiled at t and u; v, tubers on the underground stem After 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 Stevens, William Chase, 1861-. Boston, D. C. Heath & Co.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1902
