. Beginners' botany. Botany. 202 BEGINNERS' BOTANY objects when examined under the microscope (X about 200). They are spherical, green bodies, each surrounded by two spiral bands attached to the spore at their intersection, s. These bands exhibit hygroscopic movements by means of which the spores be- come entangled, and are held together. This is of advantage to the plant, as we shall see. All the spores are alike, but some of Xhepro- thallia grow to a greater size than the others. The large prothallia produce only archegonia while the smaller ones produce antheridia. Both of these organs are
. Beginners' botany. Botany. 202 BEGINNERS' BOTANY objects when examined under the microscope (X about 200). They are spherical, green bodies, each surrounded by two spiral bands attached to the spore at their intersection, s. These bands exhibit hygroscopic movements by means of which the spores be- come entangled, and are held together. This is of advantage to the plant, as we shall see. All the spores are alike, but some of Xhepro- thallia grow to a greater size than the others. The large prothallia produce only archegonia while the smaller ones produce antheridia. Both of these organs are much like those of the ferns, and fertili-. FlG. 299. — Equisetum arvense. st, sterile shoot; f, fertile shoot showing the spike at a; b, sporophyll, with sporangia; o', spore. zation is accompUshed in the same way. Since the prothallia are usually dioecious, the special advantage of the spiral bands, holding the spores together so that both kinds of prothaUia may be in close proximity, will be easily understood. As in the fern, the fertilized egg-cell develops into an equisetum plant. The sterile shoots (ji". Fig. 299) appear much later in the season. They give rise to repeated whorls of angular or furrowed branches. The leaves are very much reduced scales, situated at the inter- nodes. The stems are provided with chlorophyll and act as assimilating tissue, nourishing the rhizome and the fertile shoots. Nutriment is also stored in special tubers developed on the rhi-. 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 Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan company
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
