• Ultraviolet Photography

Barbarea vulgaris [Winter-cress]

Conical Cells
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#1 nfoto

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Posted 31 December 2012 - 02:15

Rørslett, B. 2012. Barbarea vulgaris R.Br. (Brassicaceae). Winter-cress. Flowers photographed in visible and ultraviolet light. http://www.ultraviol...s-winter-cress/

Barbarea vulgaris R.Br. (s. lat.)
Syn: B. vulgaris R.Br. var, arcuata (Opiz ex J. Presl & C. Presl) Fr.; .B. arcuata (Opiz ex J. Presl & C. Presl) Rchb.; B. vulgaris R. Br. ssp. arcuata (Opiz ex J. Presl & C. Presl) M. Loehr (var. arcuata), B. vulgaris R. Br. var. silvestris Fr. (var. vulgaris)

NO: Vinterkarse; buevinterkarse, bogevinterkarse (var. arcuata); sørlig vinterkarse, sørleg vinterkarse (var. vulgaris)
SE: Sommargyllen; vanlig vinterkarse (var. arcuata); bangyllen (var. vulgaris)
DK: Almindelig Vinterkarse (var. vulgaris), Udspærret Vinterkarse (var. arcuata)
FI: Peltokanankaali
IS: Garðableikja
DE: Echtes Barbarakraut
EN: Winter-cress

An early-flowering mustard native to Eurasia, it is widely distributed in the Nordic countries from the 17th Century onwards. Its habitats are usually quite dry and it thrives on calcareous rocks, road verges, fallow fields, along railroads, and other man-made habitats. Flowering commences early in May and continues into June.

Being of an invasive nature, B. vulgaris can replace native vegetation and is considered a severe threat to vulnerable and endangered plant communities on thin calcareous soils in coastal areas of Norway.

B. vulgaris shows dense sprays of dark yellow flowers and is eagerly visited by butterflies, hoverflies, bees, and bumblebees. One frequently observes yellow crab spiders hiding in these inflorescences ready to attack prey, usually pollen-gathering bees.

The species show considerable variation and two main types are present. The two are difficult to differentiate until fruit begins to develop, then they are easily kept apart. The taxonomic treatment ranges from having two separate species to varieties of a common B. vulgaris.

Material (var arcuata) collected near Oslo, 13 May 2012.

Attached Image: BARB_VUL_I1205240077_VIS.jpg
[Image reference: BARB_VUL_I1205240077_VIS.jpg]
Visible light: Panasonic GH-2, Coastal Optics 60 mm f/4 APO lens, Baader UV/IR Cut, studio flash.

Attached Image: BARB_VUL_I1205240065_UV.jpg
[Image reference: BARB_VUL_I1205240065_UV.jpg]
Ultraviolet light: Panasonic GH-2, Coastal Optics 60 mm f/4 APO lens, Baader U 2" (Venus) filter, Broncolor Minicom (studio flash (uncoated xenon tube).

This species may have one of the most beatiful UV patterns of all mustards. The large, dark UV marks continue into strongly prominent UV-dark veins on both sides and are even stronger present on the abaxial (lower) side of the petals. The adpressed sepals are very dark in UV and so are the buds.

Photographed at high magnification, it becomes obvious that these UV marks are closely correlated with massive development of conical cells. See picture below, taken at 3 X magnification.

Attached Image: BARB_VUL_I1105139953_UV.jpg
[Image reference: BARB_VUL_I1105139953_UV.jpg]
Conical cell structures and UV marks on petal of B. vulgaris var. arcuata. Ultraviolet light: Nikon D40X, EL-Nikkor 50 mm f/2.8 lens stacked on UV-Nikkor 105 mm f/4.5 lens plus extension, Baader U2" (Venus) filter, Broncolor studio flash (uncoated Xenon tube). Note also the very UV-dark elongate pollen grains.

[Published: 26 Dec 2012]