Juice mark

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On the right under UV light the sap marks of the juggler flowers (black area)

As juice times areas are within a flower or flower called that affect pollinators behavior. Juice marks can also be referred to as pollen or anthers dummy . These are areas of the petals that do not reflect UV light .

The significance of the juice marks was first described by Christian Konrad Sprengel in 1793 . He recognized that the sap marks show the flower visitor the way to the nectar . The exact meaning of the sap marks was only seen through later and offers a lot of space for evolutionary considerations. Probably the first visitors to the flowers were looking for food, which they found in the form of pollen in the flowers. Structures later emerged that were supposed to hide the pollen from voracious flower visitors in order to minimize pollen loss. However, the plant species affected not only had disadvantages due to such flower visits. Pollen was also transferred to other flowers, which increased their reproductive success. So in order to continue to attract visitors, other flower elements had to imitate pollen.

Juice marks are always color-coded from the rest of the blossom or flower. However , this color difference is often not visible to the human eye , as it is based on UV absorption of the sap marks. Nectar-seeking insects can see “Near UV” (UV-A), e.g. B. Wild bees up to 300 nm wavelength.

A large number of such pollen dummies are known today. These can be pronounced as two-dimensional discolorations or as three-dimensional perfect replicas of stamens.

By changing color in the area visible to humans, sap marks can tell the insects how much nectar the flower is producing. An example is the horse chestnut blossom , which indicates high nectar production with yellow juice marks that later turn from orange to red the less nectar is produced.

The sap marks are differentiated according to their shape on the petals (i.e., petals).

  • Line marks run on the petals from the inside of the flower to more or less close to the edge of the petal.
  • Circular moles begin in the center of the flower (the flower head does not reflect UV light in the daisy family) and continue over all the petals until they end at a species-specific distance and edge shape.
  • Ring marks begin at a distance from the center of the flower on the petals and end like circular marks, so that the basic shape of a ring can be recognized.
  • Speckle marks can appear as small dots or as irregular, but axially symmetrical spots in relation to the leaf axis.
  • Combined times include two distinct forms from the four basic forms mentioned above.

Web links

Individual evidence

  1. Pat Willmer: Pollination and Floral Ecology. Princeton University Press, 2011, ISBN 978-0-691-12861-0 , pp. 528 f.
  2. Hans Kugler : Flower ecological studies with bumblebees. The color sense of animals. The optical bond in nature. The juice painting problem. In: Planta , Volume 10, Springer-Verlag, 1930, pp. 229–280.
  3. a b Martin Hallmen: Observe and get to know wild bees. In: Practical lessons in biology - with templates, Ernst Klett Verlag, Stuttgart 1997, ISBN 3-12-043140-0 .
  4. Hans-Joachim Lehnert: Insects and flowers. Suggestions for the design of the theme in botanical gardens. In: Hans-Joachim Lehnert, Felicitas Wöhrmann (Ed.), Blossom Ecology at Botanical Gardens. Foxglove calls Hummel. Results of the 12th workshop of educational staff in the Association of Botanical Gardens eV from June 1997 in the Botanical Garden of the Ernst-Moritz-Arndt University of Greifswald , self-published sponsored by the Association for the Promotion of the School Biology Center Hannover eV, Osnabrück May 1998, p. 17. PDF- Document online , accessed October 10, 2014.
  5. Hans Kugler: The use of the sap mark changes in the horse chestnut blossoms by bees and bumblebees. In: Reports of the German Botanical Society, Volume 54, 1936, pp. 394–400.