Plant ID White Snakeroot
Thanks you for sending your photo to the Toronto Master Gardeners for identification.
The plant you have is a wonderful white snakeroot (Eupatorium rugosum ‘Chocolate’, aka Ageratina altissima ‘Chocolate’). It is a perennial that is native to the eastern United States. The dark bronze leaves turn green in the fall when clusters of white fluffy flowers appear. The dark purple stems provide a stunning contrast to the leaves and white flowers. It grows in zone 4-8 to a height of 90-120 cm and spread of 75-90 cm.
This perennial is so versatile. It grows in just about any conditions, from full shade to full sun, in sandy, normal or clay soil and is drought tolerant. It does not like wet feet, though.
If you like, you can share this plant with your friends or spread it around in your own garden in the spring. Just divide the roots and transplant quickly. The roots should not dry out completely in this process.
One word of caution – do not ingest any parts of this plant – they are all poisonous.
Having said that, you have a fabulous accent or background plant in your garden. It looks particularly nice with your black-eyed Susans next to it.