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Polemonium boreale [Northern Jacob's Ladder]


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#1 nfoto

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Posted 26 July 2013 - 20:43

Rørslett, B. 2013. Polemonium boreale Adams (Polemoniaceae). Northern Jacob's Ladder. Flowers photographed in visible and ultraviolet light. http://www.ultraviol...-jacobs-ladder/

Polemonium boreale Adams
NO: Polarflokk
EN: Northern Jacob's Ladder

This is a low perennial species with large pale blue flowers. It is distributed in high Arctic regions (Svalbard, Greenland, Arctic North America) and there is only a single location in mainland Europe. Here it grows on sandy calcareous soils in the middle of a churchyard. The first find was in 1863 and the entire site became protected by Law in 1919. The dead and the living have been happily co-existing since then. Churchyard management has been carefully customised so as to impact P. boreale as little as possible. Thus grass is only mowed late in the season to allow P. boreale seeds to ripen and footpaths have been laid to steer trampling away from the plant colonies. Evidently the measures work as the population was thriving at my visit.

P. boreale has fairly open flowers compared to the campanulate flowers of P. acutiflorum, with which it hybridises. Genetic pollution through hybridisation is considered a major threat to the small mainland population at Bugøynes. This is due to the fact that Polemonium species are quite commonly cultivated in local gardens. Hence there are numerous warning signs telling people not to plant such species in their gardens on on graves. Management of the protected P. boreale includes identification and physical removal of any hybrid material before hybrids can propagate further. I am uncertain if the eradication is done on a yearly basis, however, as limited resources might prevent such practice. Thus, I did notice a few plants of intermediate stature with flowers lacking the yellow throat so characteristic for P. boreale at the churchyard perimeter but did not uproot the specimens (this was before I had noticed the warning signposts).

Plants photographed at Bugøynes, Finnmark, Norway (single mainland European locality) 24 Jul 2013.

Attached Image: POLE_BOR_B1307247663_VIS.jpg
Image reference: POLE_BOR_B307247663_VIS.jpg
The habitat of P. boreale (Nikon D800, Fisheye-Nikkor 16 mm f/3.5). Equisetum arvense is a constant follower on the sandy soils. P. boreale is a weak competitor but apparently E. arvense causes it no problem.

Attached Image: POLE_BOR_B307247645_VIS.jpg
Image reference: POLE_BOR_B307247645_VIS.jpg
Visible light: Nikon D800, Voigtländer 125 mm f/2.5 APO-Lanthar, daylight

Attached Image: POLE_BOR_B307247656_VIS.jpg
Image reference: POLE_BOR_B307247656_VIS.jpg
Visible light: Nikon D800, Voigtländer 125 mm f/2.5 APO-Lanthar, daylight

Attached Image: POLE_BOR_I1307240991_UV.jpg
Image reference: POLE_BOR_I1307240991_UV.jpg
Ultraviolet light: Panasonic GH-2, Coastal Optics 60 mm f/4 APO, Baader U2" (Venus) filter, SB-140 flash.

The UV appearance shows large patches with conical cells on the corolla.

References:
http://www.ultraviol...-r%C3%B8rslett/

[Published 27 Jul 2013 Last update 29 Jul 2013]

#2 Andrea B.

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Posted 28 July 2013 - 15:20

It is a beautiful flower. I'm impressed with the care shown to preserve its growth in the churchyard.
What longitude was this location?
Andrea G. Blum
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#3 nfoto

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Posted 28 July 2013 - 19:25

69 58 N 29 38 E. So it is not very far North.

#4 Andrea B.

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Posted 29 July 2013 - 02:50

Yeah it is !!
The furtherest north I've ever been is 45°N, so 70°N seems very north to me.
Andrea G. Blum
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#5 nfoto

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Posted 29 July 2013 - 06:39

Norway extends to 71 11 N hence my comment.