What is this tree now leafing out in a Vancouver yard? It has prominent lenticels on its bark, and compund leaves. Thanks!
If you can still see its bud scales it would help to know of those are hairy and dry or hairless and sticky. Michael is probably calling it Sorbus sargentiana because of your tree's sparse and stubby branches but its new leaves look like those of the common (by far the most likely to be encountered in gardens of this region) S. aucuparia. 'Joseph Rock' wouldn't be expected to be found growing as a multistem clump.
I went for Sargent's Rowan because of the relatively few but rather large leaflets. But it isn't too easy to tell at this stage in spring.
Online Flora of China describes S. sargentiana with multiple hairy parts. Mine here looks superficially more like a sorbaria when sprouting than S. aucuparia, which has grayish hairy new growth (like that of specimen shown). http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200011714
