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Oxalis violacea [Violet Wood Sorrel]


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#1 Andrea B.

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Posted 22 May 2015 - 22:34

Blum, A.G. (2015) Oxalis violacea L. (Oxalidaceae) Violet Wood Sorrel. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...et-wood-sorrel/

Boyce Thompson Arboretum, Superior, Arizona, USA
24 April 2013
Wildflower in botanical garden

Synonyms:
  • Ionoxalis violacea (L.) Small
  • Oxalis violacea L. var. trichophora Fassett
  • Sassia violacea (L.) Holub
Comment:
Rarely found in the wild, O. violacea thrives in shaded gardens. Like other Oxalis, the edible leaves, often used in salads, have a tart lemony tang. It also has the typical UV-absorbing striped throat.

Reference:
1. New England Wild Flower Society (2015) Oxalis violacea L. Violet Wood Sorrel https://gobotany.new...xalis/violacea/

Equipment [Nikon D600-broadband + Nikon 105mm f/4.5 UV-Nikkor]

Visible Light [f/11 for 1/200" @ ISO-400 in Sunlight with Baader UVIR-Block Filter]
Attached Image: oxalisViolaceaVisFlash_042413boyceThompArbSupAZ_9181origProofPn.jpg

Ultraviolet Light [f/11 for 1/200" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]
Attached Image: oxalisViolaceaLeafUVBaadSB14_042413boyceThompArbSupAZ_9194pf01.jpg

Ultraviolet Light [f/11 for 1/125" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]
The shamrock-like leaf of O. violacea. Note the bumps of oxalate crystals around the edges of the leaf.
Attached Image: oxalisViolaceaLeafUVBaadSB14_042413boyceThompArbSupAZ_9213pf.jpg
Andrea G. Blum
Often found hanging out with flowers & bees.

#2 nfoto

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Posted 22 May 2015 - 22:51

Interesting. This species of Oxalis behaves very similar to say a Geranium sylvaticum or G. pratense by having highly UV-reflective petals the veins of which are UV-dark. I found some old material of O. tetraphylla, another violet-flowered member, which in UV appeared similar to the white-flowering O. acetosella instead. Thus it seems almost impossible to predict a UV response from the flower colour as such.

#3 colinbm

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Posted 23 May 2015 - 12:54

Nice presentation, Andrea
Do those crystals sting ?
Col

#4 nfoto

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Posted 23 May 2015 - 13:25

No, they don't. This is not in any manner similar to the nettles and their stinging allies.

The massive content of oxalic acid might make these species less palatable to herbivores though.

#5 Andrea B.

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Posted 24 May 2015 - 22:56

No, I've handled the leaves of several types of Oxalis with no harm.
Andrea G. Blum
Often found hanging out with flowers & bees.