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Cleistogamy and Chasmogamy in Bromus carinatus Hook. & Arn.
Jack R. Harlan
American Journal of Botany
Vol. 32, No. 2 (Feb., 1945), pp. 66-72
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2437112
Page Count: 7
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Observations were made on the appearance of cleistogamous florets in plants of Bromus carinatus grown under different environmental conditions. Comparisons were made at several stages of development between cleistogamous and chasmogamous panicles. Bromus carinatus is facultatively cleistogamous, producing both chasmogamous and cleistogamous florets on the same plant. Optimum conditions for flowering induce chasmogamy; adverse conditions induce cleistogamy. The developmental gradient in cleistogamous spikelets and inflorescences is much steeper than the gradient in the chasmogamous spikelets and inflorescences. Both types of florets may appear on the same panicle, due to an abrupt change in the developmental gradients at an early stage in the development of a panicle. This steepness of developmental gradient in cleistogamous spikelets is associated with marked precocity in maturation of both ovary and pollen. Morphologically, cleistogamous flowers differ from chasmogamous ones in having smaller floral organs, particularly anthers, stigmas, and lodicules.
American Journal of Botany © 1945 Botanical Society of America, Inc.