Can you suggest a low maintenance, short (~2ft), thorny shrub?

Barberry is very prickily and hardy here in the Nortwest.

Barberry is a great choice although not native. Two suggestion would be Barberry - Sunjoy™ Gold Beret or Rosey Glow depending on the color and height you are looking for. If you would like the benefit of some fruit, Gooseberries may work.

Head over to Al's Garden Center and I am sure they have what you need.

If all else fails, you could use native poison oak and they will soon stop planting their butts there. :)

Barberry springs to mind.

There are lots of kinds.... a couple are native to North America but not the Pacific Northwest.

They are beautiful shrubs year-round.... and wicked thorny.

You could also try roses.... there are varieties that grow most anywhere.... and they are sharp as needles.

EDIT: Maybe look into the Oregon-Grape Holly/ Holly-leaf barberry. It's native (it's your state flower), related to the barberry.... but without the thorns. Instead of thorny stems.... it has prickly leaves with barbs on them.... not pleasant to brush up against (but less likely to tear your skin open too).

Dwarf yaupons are extremely astounding flowers that are rather hardy. jap boxwoods are yet another shrub/bush that have finished o.k. with none authentic attempt on our area. We further offered a house that have been on the marketplace for a whilst, and each and all the flowers had died different than for those, which nonetheless regarded basically advantageous. they are thriving now with accepted watering.

Bayberry ia a good one. Ouch if you grab one.

pubes