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Concept
Geraniales
Résumé
Geraniales is a small order of flowering plants, included within the rosid subclade of eudicots. The largest family in the order is Geraniaceae with over 800 species. In addition, the order includes the smaller Francoaceae with about 40 species. Most Geraniales are herbaceous, but there are also shrubs and small trees.
Flower morphology of the Geraniales is rather conserved. They are usually perfectly pentamerous and pentacyclic without fused organs besides the carpels of the superior gynoecium. The androecium is obdiplostemonous. Only a few genera are tetramerous (Francoa, Tetilla, Melianthus). In some genera some stamens (Pelargonium) or a complete whorl of stamens are reduced (Erodium, Melianthus). In the genera Hypseocharis and Monsonia there are 15 instead of the usual ten stamens. Most genera bear nectariferous flowers. The nectary glands are formed by the receptacle and are localised at the bases of the antesepalous stamens.
The economic importance of Geraniales is low. Some species of the genus Pelargonium (Geraniaceae) are cultivated for their aromatic oil used in the perfume industry. Some other species, also mostly within Geraniaceae, have horticultural or medicinal uses. A Paleobotanic record is missing.
The botanical authority for Geraniales is given to Jussieu, but since the original description did not fulfill all the rules for a valid publication and was subsequently validly published, attribution is given to both Jussieu and the subsequent publication, hence the designation Geraniales Juss. ex Bercht. & J.Presl Jussieu, who developed the concept of botanical families, described the Gerania, as a grouping of five genera, including Geranium. Although Jussieu used the term Ordo this did not correspond to current understandings of the term Order. The subsequent attribution occurred in 1820, in the Czech text O Prirozenosti Rostlin, by Friedrich von Berchtold and Jan Svatopluk Presl, hence ex Bercht. & J.Presl. However, Berchtold and Presl also only described a rad (ordo) of five genera, which they called Geraniae.
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