PlantFiles is getting a new look! Just in time for spring, we're rolling out a new look for the best online plants database. It will also work with your smart phones and mobile devices, so now you can take it with you on garden center visits or botanical garden tours. Questions or comments? Please post them here.
For orange there is also regla, sessei, libanensis, betulifolia, pubescens (all section Erythrostachys), x jamensis Pat Vlasto and Devanteville, greggii Lowry's Peach, lasiantha.
As Robin said, it is hard to tell with scarlet forms if they are closer to red than orange.
The standard for determining colors for patents is the RHS Colour Chart. Less expensive and infrequently used is the Pantone Color Formula Guide, used for printing, painting and other graphic standards. I use the Color Picker on Photoshop to read the RGB colors from images (other bitmap graphics have their own versions)