I'm rushed for time today, so I can't write as much as I'd like. Fortunately, I can direct you to some writings describing Mahonia from the garden's interpretative sign and this thread on the garden's forums (with other photographs, including some that are just a touch more true-to-life).
This was an overexposed photograph which I decided to save by performing the calculations command in Photoshop. I selected both blue channels, inverted each, then used the “linear burn” calculation.
Photography resource link: Shooting Wildflowers via the excellent Human Flower Project weblog.
Mahonia x media 'Charity' - Z7 - RHS Index of Garden Plants, M. Griffiths
One of the things that always amazed me about the Mahonias -- strictly ornamental although I believe the berries are edible -- in my garden was the hardness of the wood. That and the astonishingly vibrant colour of the wood. Not that either is important, but I thought I'd share.
Thanks for all the fine photos.