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Studies of Paleozoic Seed Ferns: Anatomy and Morphology of Morphology of Microspermopteris aphyllum.
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- Author(s) / Creator(s)
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The discovery of numerous specimens of the monostelic pteridosperm genus Microspermop- teris in Pennsylvanian coal ball petrifactions from the Lewis Creek and What Cheer localities provides additional information about the anatomical and morphological variability within the genus. Specimens are now known up to 1.1 cm in diam that bear epidermal appendages in the form of variously-shaped trichomes. The external surface of the stem is further ornamented by longitudinal flaps of cortical tissue. Petioles exhibiting a single C-shaped vascular strand with abaxial protoxylem are produced in a 2/5 phyllotaxy. Large petiole bases that clasp the stem produce primary pinnae alternately. The presence of axillary branching appears simi- lar to that reported in Callistophyton and Lyginopteris. Triarch to polyarch adventitious roots, some with secondary tissues, are produced at both nodal and internodal regions. Of the cur- rently recognized monostelic seed fern genera, Microspermopteris is most similar to Heter- angium. Information is presented that supports current ideas regarding the evolution of the gymnospermic eustele from protostelic Devonian ancestors.
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- Date created
- 1976
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- Subjects / Keywords
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- Type of Item
- Article (Published)
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- License
- This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.