I don't think it is considered a shrub plant? Perhaps a perennial?

Looks like Oxalis regnellii var. triangularis. Cute little houseplant type. I've used them in the garden this year and dug up the rhizomes or whatever they are. I know someone in zone 7, who posts here, gets them to overwinter by burying them deeply - like 8".

Here is a link that might be useful: link to pic at Brent and Becky's