. Elementary botany. Botany. FURTHER STUDIES ON GYMNOSPERMS. 2IQ are exposed on the outer surface. All the plants of the great group to which the pine belongs have naked seeds. For this reason the name "gymnosperms " has been given to this great group. 438. Classification of gymno- sperms.—The gingko tree has until recently been placed with the pines, yew, etc., in the class coniferee, but the discovery of the spermatozoids in the pollen tube suggests that it is not closely allied with the coniferae, and that it represents a class coordinate with them. Engler arranges the living gymn
. Elementary botany. Botany. FURTHER STUDIES ON GYMNOSPERMS. 2IQ are exposed on the outer surface. All the plants of the great group to which the pine belongs have naked seeds. For this reason the name "gymnosperms " has been given to this great group. 438. Classification of gymno- sperms.—The gingko tree has until recently been placed with the pines, yew, etc., in the class coniferee, but the discovery of the spermatozoids in the pollen tube suggests that it is not closely allied with the coniferae, and that it represents a class coordinate with them. Engler arranges the living gymnosperms as follows :. Fig. 288. Spermatozoids of zamia in pollen tube j>g, pollen grain; «, a, spermatozoids. (After Webber.) Fig. 289. Spermatozoidof zamia showing spiral row of cilia. (After Webber.) Class 1. Class 2. Class 3. Class 4. Gnetales. Cycadales ; family Cycadaceae. Cycas, zamia, etc. Gingkoales ; family Gingkoaceae. Gingko. Coniferae ; family I. Taxaceae. Taxus, the common yew in the eastern United States, and Torreya, in the western United States, are examples, family 2. Pinaceae. Araucaria (redwood of California), firs, spruces, pines, cedars, cypress, etc. Welwitschia mirabilis, deserts of southwest Africa; Ephedra, deserts of the Mediterranean and of West Asia. Gnetum, climbers (Lianas), from tropical Asia and 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 Atkinson, George Francis, 1854-1918. New York, H. Holt and company
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