Hemlock is poisonous
Cow parsley looks like hemlock, but is not poisonous. It's something that's beneficial to have in grazing for livestock. Properly maintained grasslands with diverse species (that hopefully aren't poisonous) store carbon, support biodiversity, and provide food for livestock.
This is neither -- it's called hogweed and you can eat it. If you eat the seeds green they taste like gin and are kind of disgusting, but when they're dry they taste like spice. You can also eat nettles, which tend to grow near it.
Trees and shrubs (that are not poisonous) store carbon, support biodiversity, and provide shelter and environmental enrichment for animals.