This is something that showed up uninvited (as best we can tell) in our backyard garden on the east bank of the Humber fairly early this spring, By now (mid-July) it is 5=6 feet tall. PictureThis and PlantID both claim it is mulberry (either red or white) but I do not think the leaves have the correct profile. iNaturalist thinks it is Fatoua villosa. But I have not seen that reported in Toronto yet. The garden faces west, getting full sun from around mid-day.
I think it is a weed that should be removed (and I will probably do that). But I am still curious what it might be. So far it has no flowers or berries or anything else that might be an identifying feature. I have gone through your archive photos, but don’t see anything similar. I love the site; this is the first time I have asked for help.
sincerely,
A. Younger
Thank you for contacting Toronto Master Gardeners.
A weed is commonly defined as any plant growing where you don’t want it so the determination is subjective. The vigorous growth you are describing is characteristic of a tree which you may not want in that spot regardless of the identification. While it is easier to identify plants with a variety of photographs, the picture you have submitted strongly suggests that the plant is a mulberry, botanically a member of the genus Morus. Mulberries are known for having highly variable leaf shape In the photograph, the leaves and alternate placement of buds are both characteristic of mulberries, although other leaf shapes are more common, particularly on mature plants. You are unlikely to see flowers or fruit if the plant is a sapling.
Identifying the plant to the level of species is more difficult because Mulberries naturally cross-pollinate. The Red Mulberry, native to Ontario, is considered an endangered species because cross pollination with the introduced White Mulberry, Morus alba, has resulted in diminishing numbers of the native plant and a proliferation of hybrids.
Assuming that you do not want the plant, you will want to remove it as soon as you can as the longer you wait the more difficult removal will be.