Thee are growing in a swampy area in our ravine in West Toronto
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Although the photo is a little unclear, the shape of the leaves and the way they seem to be unfolding as they grow, as well as the prolific growth pattern, lead me to believe that this could be Asian bittersweet (Celastrus orbiculatus), also known as Oriental bittersweet, an invasive species. However, it could also be American bittersweet (Celastrus scandens L.), a native variety.
After consulting with one of my colleagues, another possibility would be Skunk cabbage (Symplocarpus foetidus). This native plant grows close to the ground and is known for its strong smell (the scientific name ‘foetidus” means strong-smelling). Hence the name Skunk cabbage. It usually grows in wet areas and some sources says that this plant can live for over 100 years!
Please see below links to Skunk cabbage and Asian bittersweet