Capturenx2

UV photography was conducted using a Baader U-filter. This filter transmits UV wavelengths from 325 to 369 nm, with maximal penetrance in the UV-A range at 360 nm (Savazzi, 2011 ). The filter was used with an AF Micro Nikkor 60 mm lens, several mounts, and a Nikon D70 DSLR digital camera. UV photographs were downloaded to Nikon Capture NX2 software and then transferred to Image J 1.46 for quantitative analyses. Image J is an open access processing and analysis program written in Java that can be downloaded from National Institutes of Health (http://rsbweb.nih.gov/ij). In Image J, a phenotypic trait, like petal surface area can be traced and digitized. The circumscribed area can be calculated and the resultant pixel measurement for the trait can be converted to a meaningful scale (e.g. mm²) based upon a reference scale used in the picture (here, a ruler). Multiple traits were measured including petal length, petal surface area, floral-head area, UV floral guide length, and proportion of petal surface area comprised of UV floral guide. All statistical tests were performed in SPSS.