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[Andrea B.]

Blum, A.G. (2016) Erigeron annuus (L.) Pers. (Asteraceae) Daisy Fleabane. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...daisy-fleabane/

Synonyms:

• Annual Fleabane
  
• Erigeron annuus var. discoideus (Victorin & Rouss.) Cronq.
  
• Stenactis annua (L.) Nees

Comment:
Erigeron strigosus and E. annuus can intergrade, however E. strigosus usually has entire lower leaves and stems with sparse, tightly appressed hairs while E. annuus has coarsely toothed leaves and spreading stem hairs. The almost linear leaves of E. strigosus are relatively narrower than the leaves of E. annuus. The corolla and disc in both species are UV-dark. Here the E. annuus pollen in appears brighter in UV.

SET 1
Shore Cottage, Southwest Harbor, Maine
11 August 2014
Wildflower

Reference:
1. Jepson eFLora. (2012). Key to Erigeron. Jepson Herbarium, U. of Cal.-Berkeley, Berkeley, CA.
http://ucjeps.berkel..._IJM.pl?key=429
2. New England Wild Flower Society (2016) Erigeron annuus. Annual Fleabane. https://gobotany.new...rigeron/annuus/

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

Visible Light [f/11 for 1/2" @ ISO-400 with Onboard Flash and Baader UVIR-Block Filter]


Visible Light [f/11 for 2" @ ISO-400 with Onboard Flash and Baader UVIR-Block Filter]
Note that the stem hairs are not closely pressed to the stem.


Ultraviolet Light [f/11 for 20" @ ISO-400 with SB-14 UV-modified Flash and BaaderU UV-Pass Filter]
The long exposure was chosen to permit multiple flashes for shadow reduction and increased illumination.