. Fundamentals of botany. Botany. SEED-BEARING PLANTS 397 sporophyll, Fig. 295). In the Cycads and higher plants the megasporangia are called ovules. 355. Ovules.—The young megasporangia, or ovules of Cycads consist of two distinct regions of sterile tissue—an inner nucellus, and an outer covering, or integument,. Fig. 293.—Megasporophyll (carpel) of Cycas media, bearing one ripe naked (gymnospermous) seed, and three ovules which faEed to become seeds, doubtless through not being fertilized. (Compare Fig. 292.) which is an outgrowth of the ovule just below the nucellus. The integument serves t
. Fundamentals of botany. Botany. SEED-BEARING PLANTS 397 sporophyll, Fig. 295). In the Cycads and higher plants the megasporangia are called ovules. 355. Ovules.—The young megasporangia, or ovules of Cycads consist of two distinct regions of sterile tissue—an inner nucellus, and an outer covering, or integument,. Fig. 293.—Megasporophyll (carpel) of Cycas media, bearing one ripe naked (gymnospermous) seed, and three ovules which faEed to become seeds, doubtless through not being fertilized. (Compare Fig. 292.) which is an outgrowth of the ovule just below the nucellus. The integument serves to protect the more deUcate tissues within, and later becomes transformed into the seed- coat (Figs. 296-298). Only one of the four megaspores develops within the nucellus. 356. Female Gametophjrte.—As in Selaginella, the mega- spores begin to germinate while still in the sporangium^ but now a new feature is introduced into life history;. 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 Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's son & co.
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