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Senecio jacobaea [Common Ragwort]


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Rørslett, B. 2013. Senecio jacobaea L. (Asteraceae). Common Ragwort. Flowers photographed in visible and ultraviolet light.

http://www.ultraviol...common-ragwort/

 

Senecio jacobaea L.

Syn: Jacobaea vulgaris Gaertn.

NO: Landøyda; landøyde

SE: Stånds

DK: Eng-Brandbæger

FI: Jaakonvillakko

DE: Jakobs-Greiskraut

EN: Common Ragwort; Tansy Ragwort (US)

 

This is a gregarious plant often colonising its habitats in dense stands and since it is poisonous to livestock, considered a noxious weed. Several countries (UK, Ireland) have enforced legal Acts of control measures. It is native to Eurasia and introduced to North America where it is considered invasive. Plants can be more than 1 m tall and are biennial or perennial. They overwinter as dense rosettes of basal foliage and dried stems that spread seeds..

 

The main habitats are fairly dry often sandy soils, forest edges, roadsides, and agricultural land such as pastures. It flowers copiously with flat-topped corymbs of yellow flower heads from Mid summer until late in the season (September-October). Seed set is rich and its ability to invade new territory is a reason for it being considered a problem weed. Another is its content of alkaloid components many of which are toxic to grazing animals and livestock. In the fresh state plants taste bitter so animals tend to avoid them, but dried the bitterness disappears and hay containing ragwort can cause poisoning and irreversible damages to internal organs.

 

The yellow flower heads attract a great number of pollinators. One always observes flying insects entering or leaving the flowers.

 

Plants photographed at Lier, southern Norway, 18 Aug 2005.

 

SENE_JAC_I0608189214_VIS.jpg

Image reference: SENE_JAC_I0608189214_VIS.jpg

Visible light. Nikon D70, UV-Nikkor 105 mm f/4.5 lens, daylight.

 

SENE_JAC_I0608189215_UV.jpg

Image reference: SENE_JAC_I0608189215_UV.jpg

Ultraviolet light. Nikon D70, UV-Nikkor 105 mm f/4.5 lens, Hoya U-340 filter, SB-140 flash.

 

[Published: 17 Jan 2013]

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