Botanical fever

I am plugging away in the botanicals. Yellows are hard to shade and should be shaded with 

a mix of light red and Ultramarine blue to create a "botanical grey". Two wonderful artist friends have given me beautiful books with excellent advise on this type of art. One book is titled "The Art of Botanical Painting" from the Smithsonian, the other "Botanical Illustration" by Siriol Sherlock. My shadows are almost always watery Ultramarine, watery lemon yellow or/and watery crimson alizarin.