Identification: Weed? Or keep?

This purple stemmed plant has emerged from no where in a seldom visited side yard.
The area is usually very very arid, but has received extra water this summer from a leaking hose.

It reminds me of a young peony...?

Any suggestions appreciated

 

Could it be an Astilbe?

 

My guess is Angelica gigas, so keep.

(I couldn't get the larger images, so am basing my guess on squinting at the smaller ones.)

Cheers!