Eurybia divaricata [White Wood-aster]

[Andrea B.]

Blum, A.G. (2013) Eurybia divaricata (L.) G.L. Nesom (Asteraceae) White Wood-aster. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...ite-wood-aster/

 

Hartshorne Woods Park, Middletown, New Jersey, USA

23 September 2013

Wildflower

 

Synonyms:

• Aster castaneus Burgess
  
• Aster divaricatus L.
  
• Aster excavatus Burgess
  
• Aster tenebrosus Burgess
  

Comment:

E. divaricata is quite prolific along shaded woodland paths in several of my local parks. Its yellow disc florets turn reddish as they age.

In UV the white rays become UV-dark and the disk florets turn UV-black.

 

Reference:

1. New England Wild Flower Society (2013) Eurybia divaricata. White wood-aster. https://gobotany.newenglandwild.org/species/eurybia/divaricata/

 

Equipment [Nikon D600-broadband + Nikon 105mm f/4.5 UV-Nikkor]

 

Visible Light [f/5.6 for 1/40" @ ISO 400 with Coolpix A]

 

Visible Light [f/5.6 for 1/60" @ ISO 400 with Coolpix A]

A typical shaded patch of White Wood-asters along a man-made path in Hartshorne Woods.

There is poison ivy (Toxicodendron radicans with 3 notched leaves) and Virginia Creeper (Parthenocissus quinquefolia with 5 notched leaves)

in the foreground and some young tulip trees (Liriodendron tulipifera with large lobed leaves) in the background.

 

Visible Light [f/8 for 1/60" @ ISO 400 with Coolpix A]

The phyllaries of E. divaricata help make the identification together with the hairy stems and lower heart-shaped leaves having fewer than 10 teeth.

 

Visible Light [f/11 for 1/200" @ ISO 100 with onboard Flash and Baader UVIR-Block Filter]

 

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

An extra long exposure was made in order to fire the flash three times for more even lighting in this indoor shot.

[nfoto]

Any close-ups of the capitula, Andrea? In the last picture there are clear signs of conical cells on the ray florets.

 

A tangential remark about the Parthenocissus. So nice to see it in its natural habitat. Over here it is a common ornamental plant and a true nuisance when it escapes from cultivation which happens quite frequently. Every year I try to eradicate it and tear down its climbing vines that find their way all over my wooden house, only to see them return next season in other spots. The only consolation is foliage in autumn turns into the most beautiful hues of red and orange, which is why I planted it in the first place.