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The Cretaceous Pteridosperms Ruflorinia and Ktalenia and Implications on Cupule and Carpel Evolution

Thomas N. Taylor and Sergio Archangelsky
American Journal of Botany
Vol. 72, No. 12 (Dec., 1985), pp. 1842-1853
Stable URL: http://www.jstor.org/stable/2443601
Page Count: 12
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Cretaceous Pteridosperms Ruflorinia and Ktalenia and Implications on Cupule and Carpel Evolution
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Abstract

The vegetative (Ruflorinia sierra) and fertile (Ktalenia circularis) organs of an Early Cretaceous pteridosperm collected from Santa Cruz Province in Argentina are described. The sterile leaf is at least tripinnate and bears decurrent secondary pinnae with obliquely attached, sharply pointed pinnules. The fertile member arises from the base of the vegetative rachis and bears two types of appendages, cupules and bracts. Bracts are attached to the main axis near cupules and are present in clusters of up to six. Cupules are sessile, spherical, and arranged in opposite or subopposite pairs along the axis. A small lip is present on one surface of the cupule. The number of seeds per cupule may be one or two, with each characterized by a distal nucellar beak and circular, chalazal scar. Cuticular anatomy, including the fine structure of the stomatal complex, is described for both vegetative and reproductive organs. The cupules of Ktalenia and other Mesozoic seed plants are compared, and a discussion presented regarding the possible function of the cupule.

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