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Stomata on the Ovules of Zamia floridana
American Journal of Botany
Vol. 38, No. 1 (Jan., 1951), pp. 47-53
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2437991
Page Count: 7
You can always find the topics here!Topics: Stomata, Guard cells, Ovules, Integument, Epidermal cells, Fossils, Plant cells, Mother cells, Integumentary system, Epidermis
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Stomata are described on the nucellus and integument of the ovule of Zamia. The nucellar stomata occur over the major part of the free portion of the nucellus; the integumentary stomata are restricted to the very base of the ovule. The number of stomata is more variable on the nucellus than on the integument and some strobili appear to lack nucellar stomata entirely. The integumentary stomata resemble the foliar stomata in many respects and differ considerably from the nucellar stomata. Nucellar and integumentary stomata contain plastids and can synthesize starch. The hypothesis is presented that the nucellar and integumentary stomata are controlled by separate genetic mechanisms. Fossil members of the psilophytales, ancient ferns, and pteridosperms are not reported to have stomata on the sporangia. Modern ferns also lack stomata as a sporangial character. Beania, a fossil cycad contains integumentary stomata, but no fossil has been described with nucellar stomata.
American Journal of Botany © 1951 Botanical Society of America, Inc.