hello master gardeners
could you please tell me what it is? Thank you.
Thank you for contacting the Toronto Master Gardeners with your question.
This sapling looks all too familiar since it is a frequent invasive species found both in natural settings as well as uninvited garden guests. This appears to be a glossy buckthorn (Frangula alnus), and you would be advised to remove it along with any siblings.
Buckthorns are sold in nurseries and used sometimes as screening or barrier trees, but their black persistent berries are often spread by birds and animals eating and dropping the seeds far and wide.