• Ultraviolet Photography

Orobanche gracilis [Slender Broomrape]

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#1 nfoto

    Former Fierce Bear of the North

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Posted 04 June 2015 - 22:52

Rørslett, B. 2015. Orobanche gracilis Sm. (Orobanchaceae) Slender Broomrape. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...nder-broomrape/

Orobanche gracilis belongs to a large, parasitic genus with a near Cosmopolitan distribution. It is a European species and one out of twenty Orobanche species found in Slovenia. These plants are entirely without chlorophyll and are seen as leafless stems emerging with clusters or spikes of quite small flowers of an intricate and complex design. They parasitize roots of many vascular plants and most species are confined to a single or a few hosts.

The flowers of O. gracilis smell a little sickly and unpleasantly sweet. Perhaps the flowers are pollinated by small flies or beetles?

Plants photographed in a dry upland meadow at Bohinje Jezero, Slovenia, 4 June 2015. The host plants were Trifolium spp.

Attached Image: OROB_GRAC_G1506045545_VIS.jpg
Image reference: OROB_GRAC_G1506045545_VIS
Visible light: Nikon Df, Noct-Nikkor 58 mm f/1.2 lens

Attached Image: OROB_GRAC_I1506042373_UV.jpg
Image reference: OROB_GRAC_I1506042373_UV
Ultraviolet light: Nikon D3200 (internal Baader U2" filter), Coastal Optics 60 mm f/4 APO lens, SB-140 flash

In UV, greater diversity in [false] colours is seen. There are UV-reflective parts around the entrance to the corolla throat.

[ Published 5 June 2015 ]

#2 nfoto

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Posted 05 June 2015 - 06:56

Host plants at this location subsequently were identified as Trifolium pratense and T. montanum.

I think now pollinators must be bigger creatures than small flies as postulated earlier. Still, the emitted pungent scent indicates some kind of specialisation strategy.

#3 Andrea B.

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Posted 05 June 2015 - 12:49

I searched a bit and found mention of bees or bumblebees for some Orobanche.
Also some speculation about self-pollination.

This example is one of the prettier species of Orobanche I've seen.
And the Noct certainly gives a nice portrait of it. Looks like you were around f/2 - f/4 ??
Andrea G. Blum
Often found hanging out with flowers & bees.