The picture does not give enough detail. To help identify, we need a close up picture of the leaves, flowers if any, and the bark,

Thank you

Next time I'll get a better picture. Thanks for the tip.

I just identified this "shrub" as plum tree suckers from a 4- way plum tree nearby.

Yes, European orchard plums often sucker. At Discovery Park there is a staircase that cuts through a thicket of plum suckers that, curiously, are all the same height, in the manner of a running bamboo or an aspen.