[qyph]

Blackberry has thorns and serrated leaves so you can distinguish it fairly easily regardless of season. When there are leaves on the plants there aren't really many plants that are easy to confuse with poison oak around here. Just look for leaves that come in sets of 3 leaflets with rounded/smooth lobes.

[dap]

It's great you don't have trouble. I don't have that confidence yet. I've been using a plant id app to check when I see it and I've gotten it wrong both ways.

https://www.verywellfit.com/poison-oak-photo-4020320

> The leaves may be notched, round, or oak-like depending on what other foliage is around the poison oak plants. They may be shiny—or not. They may have a red tinge—or not. This is where the challenge of identifying these plants comes into play. ... > The actual shape of poison oak's leaves change based on the environment it is growing in, with the lobes able to vary on the same plant.

That may be why I've found it hard to pin down.

[clmay]

I agree, I find it easy to identify in any season. We have few plants that resemble it or its growth habits in anything but a superficial way, plus poison oak is much less variable in leaf size and shape than poison ivy.

The buds and stem tips are especially good giveaways, but I didn't really realize it until I lived somewhere with multiple species of sumac.