Watercolor with other paints and colored pencils is the standard medium for botanical illustrations.  But in the late 18th century Mary Delany began making cut paper collages or ‘mosaicks’ as she called them.  She would cut minute pieces of paper and stick them to a solid black background. To create shading and depth smaller pieces were layered over larger ones with some parts enhanced with watercolor.  After making nearly a thousand of these masterpieces failing eyesight prevented her adding to the collection.  In 1896 much of her work was donated to the British Museum where they can be viewed here in their online collection.