There is yet one more plant that has appeared in the garden we have moved to in downtown Toronto.
This perennial gets large (about 2.5 feet tall and 3 feet wide). While it tolerates full sun, it most certainly does not like to be dry as it wilts rapidly, and recovers just as rapidly with a quick watering.
What might this plant be?
Your perennial is a ligularia, Ligularia dentata. There are upwards of 150 varieties in this plant family of ornamental herbaceous perennials, and the appearance of different cultivars varies greatly. Yours is possibly the variety ‘Othello’, with its yellow, daisy-like composite blooms, and its rounded but slightly “toothed” or serrated leaves (hence the “dentata” in its Latin name). You describe it very well: ligularia prefer damp conditions and thrive best in partial to full shade, especially in climates like ours where summer temperatures are high. Slugs are one of the few pests that afflict ligularia, as your photo shows. If you have a shadier spot in your garden, you may wish to consider transplanting your ligularia, either in the fall or next spring. Here are a couple of websites with useful details: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?.taxonid=244813&isprofile=1&gen=Ligularia