4 kinds of Monarda (Beebalm)

Here are 4 different varieties of monarda--a purplish red/pink growing in the back next to the arbor, pink growing by the porch trellis, lavender, just opening, also by the arbor, and my favorite red (Jacob Kline) in the front garden by the mailbox.

See what I mean?

Explanation

This is the top 3rd of an orchid done in colored pencil.  I unfortunately do not have a scanner with a big enough bed to do the whole piece at once, and I am having great difficulty putting the 3 scans together in Photoshop.  The reason for this is that the paper sits at different heights from the bed when I put it in different places, and this affects the color of the background.  It is hard to match up the whites, as some are in shadow.  Does anyone know where I can find a scanner with a big bed to use for this piece???

The top third of a colored pencil work