. Nature and development of plants. Botany. 384 EVOLUTION OF THE FLOWER consists of a few scales as in the sweet flag, oak, etc. (Fig. 263, B), but in higher forms, the perianth appears as the conspicuous leafy portion of the flower as in the lily (Fig. 263, C). Finally flowers appear in which the leaves of the perianth become dif- ferentiated into an outer cal)^ composed of several green sepals and a corolla of larger, more delicate and often brightly-colored leaves, called the petals (Fig. 263, D). We have now reached a point where the flower is said to be complete, consisting of all the org
. Nature and development of plants. Botany. 384 EVOLUTION OF THE FLOWER consists of a few scales as in the sweet flag, oak, etc. (Fig. 263, B), but in higher forms, the perianth appears as the conspicuous leafy portion of the flower as in the lily (Fig. 263, C). Finally flowers appear in which the leaves of the perianth become dif- ferentiated into an outer cal)^ composed of several green sepals and a corolla of larger, more delicate and often brightly-colored leaves, called the petals (Fig. 263, D). We have now reached a point where the flower is said to be complete, consisting of all the organs that are normally associated in the Fig. 264. Fig. 265. Fig. 264. Flower of strawberry with elongated receptacle bearing nu- merous spirally arranged sporophylls: A, open flower. B, flower in section, showing arrangement of parts upon receptacle, r, which forms a shallow cup at base bearing the perianth and microsporophylls. C, the fruit or enlarged receptacle bearing the minute spirally-arranged megasporophylls. Fig. 265. Flowers with shortened receptacles: A, flower of Pyrola with calyx and corolla arranged in whorls or cycles. B, section of flower, showing all the organs in cycles. C, flower of geranium. D, flower with corolla removed to show the coherence of the five megasporophylls that results from the shortening of the receptacle. As stated above the simpler type of flower is characterized by numerous sporophylls, spirally arranged and separately at- tached to an elongated receptacle. One of the most important variations that appeared in the evolution of the flower is asso- ciated with the shortening of this receptacle. This is brought. 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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