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Blackstonia perfoliata [Yellow-wort]


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#1 nfoto

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Posted 12 April 2013 - 23:54

Rørslett, B. 2013. Blackstonia perfoliata (L.) Huds. (Gentianaceae). Yellow-wort. Flowers photographed in visible and ultraviolet light. http://www.ultraviol...ta-yellow-wort/

Blackstonia perfoliata (L.) Huds.
EN: Yellow-wort

This is a quite small (10-40 cm tall) perennial species of calcareous dry soils and dunes. It is wide-spread in Continental Europe and Britain, but not very common.

The small, bright yellow flowers are borne in terminal cymes. Pollinators are readily attracted to these flowers and one can observe them eagerly zooming into the flowers from a distance. Sometimes there is a fierce fight for landing space amongst the visiting pollinators. The flowers open only in sunlight and close rapidly when the sun is covered by clouds.

Plants photographed at Sigournais, Vendée, France 1 June 2011.

Attached Image: BLAC_PER_Z1106015493_VS.jpg
Image reference: BLAC_PER_Z1106015493_VS.jpg

Visible light: Nikon D3S, Voigtländer 125 mm f/2.5 APO-Lanthar lens, daylight. Pollinators struggle to find a landing spot on a flower.
:
Attached Image: BLAC_PER_I1106013624_UV.jpg
Image reference: BLAC_PER_I1106013624_UV.jpg

Ultraviolet light: Nikon D40X, UV-Nikkor 105 mm f/4.5 lens, Baader U 2" (Venus) filter, SB-140 flash.

The UV marks are large and prominent. The corolla is densely covered with conical cells.

[Published 13 Apr 2013]