Mystery Solved!

Scott Belin

 is hereby recognized

 as

 plant sleuth extraordinaire

 for identifying the Angelica

 that mysteriously grew in my garden. 

My neighbor and I were stumped by a plant that showed up out of nowhere last year and  wintered over successfully. In April, Scott Belin responded to this post and identified it as Angelica. As he predicted, this year it has grown very tall and is producing many flower heads.

--Bernice