Aethophyllum stipulare
| Aethophyllum stipulare | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Anisium ( Triassic ) | ||||||||||||
| 246 to 237 million years | ||||||||||||
| Locations | ||||||||||||
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Voltzia sandstone (Grès à Voltzia), Vosges |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Aethophyllum | ||||||||||||
| Brongn. | ||||||||||||
| Scientific name of the species | ||||||||||||
| Aethophyllum stipulare | ||||||||||||
| Brongn. | ||||||||||||
Aethophyllum stipulare is an extinct representative of the Voltziales , formerly related to the conifers . It is the only known herbaceous representative of the Coniferopsida .
features
Fully grown plants are rarely more than two meters high. Plants 30 cm high are fertile. The trunk has a diameter of up to two cm and is not very branched. The trunk type is a Eustele , the protoxylem is inside (endarch). The trunk is traversed by numerous air-filled cavities. The marrow in the trunk center is parenchymal . Secondary xylem (wood) is practically not formed.
The leaves are numerous and linear. They are 5 to 30 cm long and 0.2 to 0.9 cm wide. They are seated, have parallel nerves with four to seven nerves and run down the axis.
Reproductive organs
The female cones are in groups on the lower side branches. They are 3.5 to 22 cm long and 1 to 2 cm in diameter. The bract-seed-scale complexes are arranged in a helical arrangement on the pin axis. The bracts are linear. In the armpit of each bract there is a seed scale. This has five horn-like appendages, on each of which sits at the base a backward curved ovule , the micropyle of which points towards the cone axis. Bract and seed scale are fused together at their base and form a kind of stalk.
The long male cones are at the top of the plants. They are ellipsoidal, around 5 cm long with a diameter of 1.5 cm. They have numerous, densely imbricated sporophylls. These are stalked and shield-like. They have four to six elongated sporangia on the underside . The pollen is bisaccat.
All branches of the plant end in cones. No branch can therefore continue its apical growth after cone formation. Although the plants could continue to grow via axillary buds, the lack of larger plants suggests that Aethophyllum had a determined growth.
Seedlings
The seeds germinated epigeously . The hypocotyl is well developed and usually has two cotyledons . The primary leaves then resemble the later leaves, but are smaller. Even the cotyledons are linear and have parallel veins.
The cotyledons are two-veined, the following leaves four-veined, while the leaves on older plants usually have six veins.
ecology
Aethophyllum stipulare grew very quickly. The plant grew in the floodplains of a river delta . It produced seeds at the same time that the secondary growth began, i.e. within a year. It was a ruderal plant that could quickly colonize the dry areas of the river delta. The seed production then took place before the next flood. Herbaceous ruderals today on angiosperm limited. This growth strategy had long been regarded as the cause of the success of the flowering plants, but with Aethophyllum it had already developed before the flowering plants appeared.
Systematics
The genus Aethophyllum and the species Aethophyllum stipulare were first described by Adolphe Brongniart in 1828 . Schimper and Mougeot placed them in 1844 as monocotyledons , August Schenk identified them in 1891 with Schizoneura paradoxa , a representative of the Equisetales . Karl Mägdefrau recognized in 1942 that there were two different species. It was not until 1975 that the Grauvogel strain and the Grauvogel recognized that Aethophyllum was a conifer. They could also assign the isolated male cones described in 1973 as Masculostrobus acuminatus to the species Aethophyllum stipulare .
The species is described by Taylor et al. placed in the Voltcial order, but not assigned to a family due to insufficient information, so it is incertae sedis .
In a cladistic study, Aethophyllum came to lie as a sister group of ( Dolomitia cittertiae + Majonica alpina ) within the Voltza-like Voltcials . These are late Permian and Triassic forms.
supporting documents
- ^ William A. DiMichele, Robert A. Gastaldo: Plant Paleoecology in Deep Time . Annals of the Missouri Botanical Garden, Volume 95, 2008, pp. 144-198, here 148.
- ^ A b c Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants . Second Edition, Academic Press 2009, ISBN 978-0-12-373972-8 . P. 823.
- ↑ a b c d e Léa Grauvogel-Stamm, Louis Grauvogel: Aethophyllum Brongniart 1828, conifère (non équisétale) du grés à Voltzia (red sandstone supérieur) des Vosges (France). Note préliminaire . Géobios, Volume 8, 1975, pp. 143-146. doi : 10.1016 / S0016-6995 (75) 80012-X
- ↑ a b c Aljos Farjon: A Natural History of Conifers . Timber Press, Portland 2008, ISBN 978-0-88192-869-3 , p. 88.
- ^ A b Gar W. Rothwell, Léa Grauvogel-Stamm, Gene Mapes: An herbaceous fossil conifer: Gymnospermous ruderals in the evolution of Mesozoic vegetation . Palaeogeography, Palaeoclimatology, Palaeoecology, Vol 156, 2000, pp 139-145. doi : 10.1016 / S0031-0182 (99) 00136-4
- ^ Gar W. Rothwell, Gene Mapes, Genaro R. Hernandez-Castillo: Hanskerpia gen. Nov. and phylogenetic relationships among the most ancient conifers (Voltziales) . Taxon, Vol. 54, 2005, pp. 733-750.