These are plants that are generally not for sale, but have colonized our wild spaces and will be happy to fill any gap in your garden. Learn to identify and get rid of them. The ones marked with an asterisk are aggressive and hard to eradicate.
Acer negundo Manitoba maple
Alliaria petiolata* Garlic mustard
Butomus umbellatus Flowering rush
Centaurea maculosa Spotted knapweed
Cirsium arvense Canada thistle
Cynanchum rossicum* Dog-strangling vine
Hemerocallis fulva Orange daylily
Heracleum mantegazzianum* Giant hogweed
Hesperis matronalis Dames rocket
Lysimachia nummularia Moneywort
Lythrum salicaria Purple loosestrife
Melilotus alba* White sweet clover
Melilotus officinalis Yellow sweet-clover
Myosotis scorpioides* True forget-me-not
Nepeta cataria Catnip
Pinus sylvestris Scots pine
Polygonum cuspidatum* Japanese knotweed
Phragmites australis* Common reed
Populus alba* White poplar
Rhamnus cathartica* Common buckthorn
Rhamnus frangula* Glossy buckthorn
Syringa vulgaris* Lilac
Urtica dioica ssp. dioica European stinging nettle
Vinca minor* Periwinkle