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- Tschan, Georg F., et al.
(författare)
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Credneria and Platanus (Platanaceae) from the Late Cretaceous (Santonian) of Quedlinburg, Germany
- 2008
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Ingår i: Review of Palaeobotany and Palynology. - : Elsevier BV. - 0034-6667 .- 1879-0615. ; 152:04-mar, s. 211-236
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Tidskriftsartikel (refereegranskat)abstract
- Foliage and reproductive structures of Platanaceae from the Upper Cretaceous (Santonian) of Quedlinburg, Central Germany, were comparatively studied and their systematic affinities established. One type of foliage preserved in sandstone and rarely in clayish siltstone belongs to the extinct genus Credneria. The leaves are typically obovate with a pinnate-actinodromous venation and distinct suprabasal veins. In addition, a substantial number of leaves preserved in siltstone and rarely in sandstone are identical to modern Platanus based on leaf architecture and epidermal features. As in modern Platanus leaf margin and size were found to be of no systematic significance in both fossil leaf types. Further, staminate flower heads preserved as cleavage compressions in siltstone were found in association with Platanus leaves; they contain pollen that is identical to modern Platanus in size and type of tectum. In addition. a few three-dimensionally preserved staminate flower heads with ca. 50 flowers on a receptaculum are described. Each flower appears to have a two-whorled perianth and six or seven stamens. The organs of the outer perianth whorl show a distinct epidermal cell pattern different from the inner ones. All perianth organs have the same length as the stamens. Stamens are bithecate and contain pollen identical to that found in compression fossils. Pistillate heads preserved in siltstone consist of numerous achenes with persistent styles, which show close similarity to modern Platanus. It remains unclear, whether additional inflorescence heads of uncertain sex found in sandstone that are slightly larger than those preserved in siltstone belong to the leaves of Credneria. Association evidence links vegetative and reproductive structures preserved in siltstone and indicates the presence of the modern genus Platanus in the Santonian.
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| 2. |
- von Balthazar, Maria, et al.
(författare)
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Floral Structure and Organization in Platanaceae
- 2009
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Ingår i: International journal of plant sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 170:2, s. 210-225
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Tidskriftsartikel (refereegranskat)abstract
- Developing and mature inflorescences and flowers of several representatives of Platanus were studied to clarify various aspects of floral structure and organization. Special attention was given to perianth differentiation. Extant Platanaceae are monoecious with unisexual flowers aggregated into compact, spherical inflorescence heads. Development of hairs in a basipetal direction subdivides the undifferentiated inflorescence surface into floral zones. Development of both male and female flowers of Platanus 3 hispanica begins with the initiation of a perianth whorl. Thereafter, the reproductive organs emerge on the floral apex: stamens in male flowers, staminodes and carpels in female flowers. The last organs to appear in both sexes are the small organs located between perianth and androecium. At anthesis, in both male and female flowers, organs of the first whorl are inconspicuous, scalelike, and only two to three cell layers thick. Alternating with these first thin organs is a whorl of short but fleshy organs. These second-whorl organs are basally united with the stamens, forming a short androecial tube. They also show some structural similarities with stamens. These features support the hypothesis that the second-whorl organs are of androecial (staminodial) origin. This hypothesis is further supported by the fossil record, where, in some taxa, second-whorl organs are particularly similar to stamens, as well as by morphological comparisons with flowers of Proteaceae.
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| 3. |
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| 4. |
- von Balthazar, Maria, et al.
(författare)
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Oliniaceae
- 2007
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Ingår i: The families and genera of vascular plants. - : Springer, Berlin. ; , s. 260-264
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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