I harvested some oregon grape root and leaf today for medicine. This variety is Mahonia/Berberis nervosa and it is a prolific understory plant where I live on Vancouver Island. M. aquifolium is also around, but you are more likely to find it on the south island or as part of landscaping. In some areas of North America oregon grape is not prolific.
So while I harvest quite a lot of it yearly and use it as a staple in my practice, it is not always advisable to do so in certain bio-regions. It is important to focus on using plants that can be ethically harvested/wildcrafted/grown.
The berries of these plants are edible and I quite like them, but some people find them too sour. They are high in pectin as well and can be used as an add in to preserves. I use the roots, the leaves, and the berries medicinally. I most often use the roots and I prepare them as tea or tincture for treating a variety of issues. I use this herb in formula a lot for bacterial infections, parasitic infections, and digestive issues. I also use it as a wash (usually with other herbs as well) for infected wounds and it is great for bacterial conjunctivitis as well. It is primarily bitter and energetically cooling to the system so I consider its use in the context of hot conditions according to a Chinese medicine energetic paradigm.
When you scratch at the root you should be able to see bright yellow (sometimes a bit orangey) shining out at you.
Here's another shot of the inside - there is a pithy inner part to the root and you can see the bright yellow colour again
I was mostly harvesting roots today, but I kept some leaves for medicine as well.