Sonchus asper [Spiny Sowthistle]

[Andrea B.]

Blum, A.G. (2015) Sonchus asper (L.) Hill (Asteraceae) Spiny Sowthistle. Flowers photographed in ultraviolet and visible light. http://www.ultravioletphotography.com/content/index.php/topic/1416-sonchus-asper-spiny-sowthistle/

 

Trenton, Maine, USA

02 August 2014

Wildflower

 

Comment:

S. asper has large, strongly curved, stiffly prickled "ears", or auricles, which clasp the stem.

In Ultraviolet light, S. asper has a UV-dark central area with brighter ray tips as do other Sonchus such as S. oleraceus and S. arvensis. S. asper typically has stipitate glands on phyllaries and peduncles.

 

Reference:

1. New England Wild Flower Society (2015) Sonchus asper (L.) Hill. Spiny-leaved Sow-thistle. https://gobotany.newenglandwild.org/species/sonchus/asper/

 

Equipment [Nikon D600-broadband + Carl Zeiss 60mm f/4.0 UV-Planar]

 

Visible Light [f/11 for 1/50" @ ISO-100 with Onboard Flash and Baader UVIR-Block Filter]

 

Visible Light [f/11 for 3" @ ISO-100 in Sunlight with Baader UVIR-Block Filter]

The curved, clasping auricles.

 

Ultraviolet Light [f/11 for 20" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

^{A long exposure was made to multiple flashes for more even lighting.}

 

Ultraviolet Light [f/11 for 15" @ ISO-400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

^{A long exposure was made to multiple flashes for more even lighting.}