Three-furrow pollen dicotyledonous

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The division of living beings into systematics is a continuous subject of research. Different systematic classifications exist side by side and one after the other. The taxon treated here has become obsolete due to new research or is not part of the group systematics presented in the German-language Wikipedia.

The Rosopsida or Dreifurchenpollen-dicotyledonous form a taxon of plants from the department of flowering plants (Magnoliophyta). Like all dicotyledonous flowering plants, your embryo has two cotyledons , but emerges from pollen with three characteristic furrows that are only visible in an electron microscope image. This special type of pollen grain is called tricolpat , i.e. three-furrowed.

In the systematics of biology, this group was only newly defined a few years ago, when modern technology recognized the previously unknown type of pollen grain . In some systems it is placed as a third class next to the monocots and remaining dicotyledons . It is often referred to as Eudicots or True Dicotyledons . The group's pollen can be detected in formations older than 126 million years ( Lower Cretaceous ). The oldest buttercup fossil found, Leefructus mirus , is approximately 122.6 to 125.8 million years old.

properties

In the vegetative area, the Rosopsida can hardly be distinguished from the remaining dicotyledons. However, few things can be generalized. The leaves are often compound and the widespread stipules are paired and ingrown. Transversal prophylls are located on the axillary rungs. The flower is usually four to five-fold, arranged in whorls and (often several times) divided into calyx and crown. Stamens are usually arranged in one or two circles, but often occur more often ( polyandry ). Carpels are often fused together ( coenocarp ).

Systematics

Individual evidence

  1. ↑ James A. Doyle, Carol L. Hotton: Diversification of early angiosperm pollen in a cladistic context. In: Stephen Blackmore, Susan H. Barnes (Eds.): Pollen and Spores: Patterns of Diversification. Clarendon, Oxford 1991, ISBN 0-19-857746-X , pp. 169-195.
  2. ^ Ge Sun, David L. Dilcher et al. a .: A eudicot from the Early Cretaceous of China. In: Nature. 471, No. 7340, 2011, pp. 625-628, doi : 10.1038 / nature09811 .

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