Geum rivale x urbanum, G. x intermedium [Hybrid Avens]

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Rørslett, B. 2012. Geum rivale L. x urbanum L., G. x intermedium Ehrh. (Rosaceae). Hybrid Avens. Flowers in visible and ultraviolet light. http://www.ultraviol...m-hybrid-avens/

 

Geum rivale L. x urbanum L. (G. intermedium Ehrh.)

 

Although the parents have slighly different ecology, they often grow adjacent to each other and the hybrid between them is not uncommon. The hybrid is sterile, but show great vigour and may propagate by vegatative means.Occasionally seeds might develop but whether they germinate in unknown.

 

Below are a few shots of the hybrid to show its intemediate growth habitus. The flowers are drooping like G. rivale but not to the same extent and the petals are spreading not closed. Pollinators frequently visit these flowers.

 

Specimens collected at Ljan near Oslo, Norway 21 June 2012.

 

 

Visible light: Nikon D300, Medical-Nikkor 120 mm f/4 lens, built-in ring flash.

 

 

Visible light: Nikon D300, Medical-Nikkor 120 mm f/4 lens, built-in ring flash. Hybrid flower to the left, Geum urbanum to the right. The hybrid has flowers near twice as large and the petals are not fully spreading like with G. urbanum.

 

Here is the UV record of the first flower above.

 

 

Noteworthy is that the petals in UV are different in terms of reflectivity on the proximal and distal side. This clearly is a trait derived from G. rivale since G. urbanum shows no such differentiation.

 

Below is a UV comparison shot of G. x intermedium (left) and G. urbanum (right). Basically the parent and the hybrid share their overall UV patterns. The other parent, G. rivale, was not in flower at the site so could not be documented this time.

 

Both UV pictures taken with Panasonic GH-2, Coastal Optics 60 mm f/4 lens, Baader U 2" (Venus) filter, SB-140 flash.

 

[Last update 26 Dec 2012]