Erysimum cheiranthoides [Little Wallflower]

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Rørslett, B. 2012. Erysimum cheiranthoides L. (Brassicaceae). Little Wallflower. Flowers photographed in visible and ultraviolet light. http://www.ultraviol...tle-wallflower/

 

Erysimum cheiranthoides L.

NO: Åkergull

SE: Åkerkårel; åkergyllen

DK: Gyldenlak-Hjørneklap

FI: Peltoukonnauris

DE: Acker-Schöterich

EN: Little Wallflower; Treacle-mustard

 

A small to medium-sized annual or short-lived biennal plant, E. cheiranthoides is a variable species that sometimes are divided into two subspecies (ssp. cheiranthoides and ssp. altum Ahti). The material studied by me belongs to the nominal race (ssp. cheiranthoides).

 

This species is a weed but never a problematic one and always is found on disturbed or intermittent habitats such as along side walks, road verges, fallow fields, or industrial sites. The flowers themselves are quite small, petals often are exserted just a few mm, but one frequently observes small pollinators visiting them. It begins flowering in late May or early June and can continue producing flowers until plants are killed by winter frost in October or November. I've seen flowers on this small Wallflower even in the beginning of December, but as this is an annual, it is pretty difficult to interpret the underlying strategy of the plant since developing mature seeds this late in the year is near impossible.

 

All photographs shown below are photomacrographs at 5X magnification from specimens collected near Oslo, Norway, 7 June 2010.

 

Image reference: ERYS_CHE_I1006072553_VIS.jpg

Visible light: Nikon D200, Coastal Optics 60 mm f/4 lens (reverse-mounted), Baader UV/IR Cut filter, Broncolor Minicom studio flash.

 

Image reference: ERYS_CHE_I1006074382_UV.jpg

Ultraviolet light: Nikon D40X, Coastal Optics 60 mm f/4 lens (reverse-mounted), Baader U 2" (Venus) filter, Broncolor Minicom studio flash.

 

Image reference: ERYS_CHE_I1006074203_UV.jpg

 

This is a species with prominent large marks on its petals, in fact, such marks are present on both sides. Venation is marked too in UV, but even stronger so on the lower side of the petals. Sepals are very UV-dark. The stellate hairs, typical for E. cheiranthoides, are shiny white in UV.

 

[Published: 26 Dec 2012. Last update: 17 Jan 2013]