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Hieracium umbellatum [Narrow-leaved Hawkweed]


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Rørslett, B. 2014. Hieracium umbellatum L. (Asteraceae). Narrow-leaved Hawkweed. Flowers photographed in visible and ultraviolet light. http://www.ultraviol...eaved-hawkweed/

 

Hieracium umbellatum L.

NO: Skjermsveve

SE: Flockfibbla; nolanabber

DK: Smalbladet Høgeurt

FI: Sarjakeltano

DE: Doldiges Habichtskraut

EN: Narrow-leaved Hawkweed; Northern Hawkweed

 

This member of the contentious, some would say disasterous, genus Hieracium, is not apomictic like so many other hawkweeds, but an 'ordinary' sexual species. Thus, it shows a great deal of variation in its morphology, but the specific characteristics of stiff many-leaved tall stems, usually 0.5 m, leaf margins rolled or bent inwards, and a terminal corymb with many large flower heads set it apart from most other hawkweeds.

 

It inhabits dry meadows going all the way from coastal sites into the upland regions of Europe and Asia. Flowering typically is mid to late summer and I have seen it in flower ultimo September on upland sites. There are closely related or possibly conspecific entities in North America so the overall distribution may be circum-boreal.

 

EOL (2014) lists no less than 105 synonyms for this species. The synonyms includes the North American entries H. kalmii L. and H. canadense Michx.

 

Material was collected near Oslo, Norway 18 July 2014. The plants were abundant in a dry meadow on calcareous soils.

 

HIER_UMB_B1407184999_VIS.jpg

Image reference: HIER_UMB_B1407184999_VIS.jpg

Visible light: Nikon Df, Voigtländer APO-Lanthar 125 mm f/2.5 lens, daylight. Windy conditions rob the image of peak sharpness, on the other hand, the wind does bring out the 'roughness' and slight disorder of the ray flowers, which is very typical for H. umbellatum.

 

HIER_UMB_I1407182039_UV.jpg

Image reference: HIER_UMB_I1407182039_UV.jpg

Image reference: Nikon D3200 (modified), UV-Nikkor 105 mm f/4.5 lens, internal Baader U2" (Venus) filter, SB-140 flash.

 

By a stretch of imagination, one may designate the UV signature of H. umbellatum as a "bull's eye" pattern. Much of this effect is lost as the central ray flowers develop. The corolla is UV dark on its outside, but turn a false-colour UV blue when the floret opens. The anther tube and stigmas are UV dark, as so frequently seen in the Asteraceae. Each ligule (ray) has 5-toothed tips which are UV dark. The involucre is quite UV dark as well.

 

References:

Encyclopedia of Life (EOL): Hieracium umbellatum L. http://eol.org/pages.../names/synonyms (retrieved 18 July 2014)

 

[ Published 18 July 2014 ]

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Yes, this is my H. kalmii. I went with the naming by the local 'authority' Flora Novae Angliae.

But Flora of North America lists this flower as H. umbellatum also.

 

The spreading phyllary tips are a characteristic of this plant.

I wish you had a leaf to show me.

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