Ranunculus acris [Tall Buttercup]

[Andrea B.]

Blum, A. G. (2012) Ranunculus acris L. (Ranunculaceae) Tall Buttercup. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...ll-buttercup-1/

Updated: 02 Sep 2018

 

Synonyms:

• Ranunculus acer auct.
  
• Ranunculus stevenii Beck
  
• Meadow Buttercup
  
• Giant Buttercup
  

Comment:

R. acris is usually found in damp areas. It can be distinguished from the similar R. repens (http://www.ultraviol...ping-buttercup/) and R. septrionalis by its stalkless and deeply divided leaflets.

 

The shiny corolla of the various buttercups makes for a little difficulty when photographing them in either visible or UV light. As light passes through the epidermal carotenoid pigment, yellow is reflected. The light then reflects off the underlying starch layer to add some diffuse backscattered yellow light. Topping this off, so to speak, the flat, non-striated cuticle produces a broadband specular reflection.⁽³⁾

^{[Edit: An incorrect reference to conical cells was removed from this paragraph. A more detailed explanation was added from the referenced paper.]}

 

In the UV shot you can see the white 'blowout' that can occur in the photograph. We have speculated that this shininess may also act as a kind of pollination signal in various flowers. In these buttercups the dark UV bulls-eye matches the visible bull-eyes which are darker yellow than the rest of the corolla.

 

Reference:

1. Mittelhauser et al. (2010) Tall Buttercup, page 295. The Plants of Acadia National Park. The U. of Maine Press, Orono, ME.

2. Newcomb, L. (1977) Tall Buttercup, page 242. Newcomb's Wildflower Guide. Little, Brown & Co., New York City, NY.

3. Vignolini et al. (2011) Directional scattering from the glossy flower of Ranunculus: how the buttercup lights up your chin. Journal of the Royal Society Interface, v9 no71 pp1295-1301.

 

 

SET 1

Southwest Harbor, Maine, USA

13 July 2007

Wildflower

 

Equipment [Nikon D200-broadband + Nikon 105mm f/4.5 UV-Nikkor]

 

Visible Light [f/16 for 1/250" @ISO 400 in Sunlight with Baader UVIR-Block Filter]

 

Ultraviolet Light [f/16 for 2" @ISO 400 in Sunlight with Baader UV-Pass Filter]

 

 

SET 2

Southwest Harbor, Maine, USA

15 July 2008

Wildflower

 

Equipment [Nikon D200-broadband + Nikon 105mm f/4.5 UV-Nikkor]

 

Visible Light [f/11 for 1/350" @ISO 400 in Sunlight with Baader UVIR-Block Filter]

 

Ultraviolet Light [f/11 for 3" @ISO 400 in Sunlight with Baader UV-Pass Filter]

 

 

SET 3

Southwest Harbor, Maine, USA

11 July 2012

Wildflower

 

Equipment [Nikon D300-broadband + Carl Zeiss 60mm f/4.0 UV-Planar]

 

Visible Light [f/16 for 1" @ ISO 200 with onboard Flash and Baader UVIR-Block Filter]

 

Ultraviolet Light [f/16 for 1" @ ISO 200 with SB-14 UV-modified Flash and Baader UV-Pass Filter]