. A textbook of botany for colleges and universities ... Botany. SPERMATOPHYTES 261 the ovules may be foliar or cauline. In the different groups of angio- sperms, however, the ovules are borne in very definite ways. General structure. — In the development of the ovule, the nucellus first appears as a protrusion from the surface which bears it; later a ring arises around its base, which develops into an integument; and still. Fig. 581. — Development of an anatropous ovule, the series beginning at the left; the two integuments appear successively and gradually overtop the nucellus as the ovule b
. A textbook of botany for colleges and universities ... Botany. SPERMATOPHYTES 261 the ovules may be foliar or cauline. In the different groups of angio- sperms, however, the ovules are borne in very definite ways. General structure. — In the development of the ovule, the nucellus first appears as a protrusion from the surface which bears it; later a ring arises around its base, which develops into an integument; and still. Fig. 581. — Development of an anatropous ovule, the series beginning at the left; the two integuments appear successively and gradually overtop the nucellus as the ovule becomes curved; last figure a section showing relation of the two integuments and the nucellus at maturity of ovule. — After Gray. later a second ring may arise outside of the first, which develops into a second integument (fig. 581). Soon the integument (or integuments) overtops the nucellus, and where it closes in over the nucellus there is left a narrow, more or less elongated passageway, the micropyle (fig. 582). Among the Archichlamydeae and monocotyledons there are m em-,. 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 Coulter, John Merle, 1851-1928; Barnes, Charles Reid, 1858-1910, joint author; Cowles, Henry Chandler, 1869- joint author. New York, Cincinnati [etc] American book company
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