. Nature and development of plants. Botany. DEVELOPMENT OF PLANTS 347 of Selaginella have a creeping habit like that of Lycopodium, and the aerial stems are covered with leaves arranged in several rows, very frequently in four rows of two large and two smaller leaves (Fig. 241, i^). Usually but a single chloroplast appears in each cell, as already noticed in several algae and in the Antho-. FiG. 241. A common cultivated Selaginella: i, habit of the plant—^, strobili; b, a branch bearing roots, r. lA, portion of stem, showing leaf ar- rangement.—H. O. Hanson. cerotales. The roots are frequently
. Nature and development of plants. Botany. DEVELOPMENT OF PLANTS 347 of Selaginella have a creeping habit like that of Lycopodium, and the aerial stems are covered with leaves arranged in several rows, very frequently in four rows of two large and two smaller leaves (Fig. 241, i^). Usually but a single chloroplast appears in each cell, as already noticed in several algae and in the Antho-. FiG. 241. A common cultivated Selaginella: i, habit of the plant—^, strobili; b, a branch bearing roots, r. lA, portion of stem, showing leaf ar- rangement.—H. O. Hanson. cerotales. The roots are frequently developed from the en,d of naked branches that extend from the stems to the ground (Fig. 241, r). {a) Sporangia and Spores.—^The sporangia are borne on the stems in the axils of the leaves which form a strobilus, as in Lycopodium. However, they differ radically from those of the Lycopodium, in that two kinds of spores are formed, small spores or microspores and larger ones or megaspores. The formation of two kinds of spores, or heterospory, is not confined to the Lycopodiales. It occurs among certain genera of the Filicales. 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 Curtis, Carlton Clarence, 1864-1945. New York, H. Holt
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