Utrechtiaceae
| Utrechtiaceae | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Lebachia piniformis fossil |
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| Temporal occurrence | ||||||||||||
| Upper Carboniferous to Lower Permian | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Utrechtiaceae | ||||||||||||
| Mapes & GW Rothwell |
The Utrechtiaceae are an extinct family of conifers from the order of the Voltziales .
features
The representatives are forest trees with vertical (orthotropic) trunks and approximately horizontally ( plagiotropic ) leafy side shoots. At least in Utrechtia piniformis the side shoots are in whorls. The trunk is a Eustele , resin canals are missing.
The leaves are scaly, screw-like and only a few millimeters long. They are only supplied by a vascular bundle .
The reproductive organs consist of cone-shaped structures at the ends of leafy branches. The cones are unisexual, male and female organs were probably formed on different parts of the rungs. The female pin consists of a central axis on which two-part bracts sit in a helical arrangement. In the axils of the bracts arise short shoots, on the axis of which there are several sterile scales and one or more fertile scales. Each fertile scale has an inverted ovule , that is, its micropylene opening points towards the axis. In Utrechtia floriniformis , a female cone is around seven centimeters long, the side axes around eight millimeters.
The male cones look relatively modern. They are always terminal on the leafy branches. The cone consists of a central axis on which there are flat microsporophylls in a helical arrangement . Each sporophyll has a bent end that overlaps the overlying sporophyll. A small, basal expansion on the sporophyll partially covers the pollen sacs ( microsporangia ). These sit in pairs on the underside of the sporophyll and open with longitudinal slits. The pollen grains are monosaccate, so they have an air sac. Some pollen grains are up to 280 micrometers in diameter. Pollen obtained from the cones corresponds to the pollen genus Potonieisporites , pollen from the genus Ortiseia corresponds to the genus Nusckoisporites .
Systematics
The following genera are counted among the Utrechtiaceae:
- Lebachia
- Ernestiodendron : The leaves are almost at right angles from the branches.
- Ortiseia : the leaves are helically arranged, the stomata are dicyclic.
- Moyliostrobus : known from the Lower Permian of Texas ( Moyliostrobus texanum ).
- Otovicia
Walchia is a form of poorly preserved fossils. Walchiostrobus is a form genus for female cones, Walchianthus for male cones, which were found in isolation and cannot be assigned to any genus. The representatives were listed by earlier authors as Lebachiaceae or Walchiaceae, and the Utrechtiaceae are often found under the order Voltziales.
supporting documents
- Thomas N. Taylor, Edith L. Taylor: The Biology and Evolution of Fossil Plants . Prentice Hall, Englewood Cliffs 1993, pp. 676-679, ISBN 0-13-651589-4
Individual evidence
- ^ Charles B. Beck: Origin and Evolution of Gymnosperms . Columbia University Press, New York 1988, ISBN 0-231-06358-X
