Crown Vetch (Coronilla varia) could be a charming little plant, with its pink bloom, if it didn't spread, and spread, and dominate all other plants in the field.

Japanese honeysuckle (Lonicera Japonica) forms a fast-growing vine that twists its way up shrubs and small trees to finally smother them.

Japanese knotweed (Polygonum cuspidatum) is spreading along the riversides of New Jersey, standing tall on hollow stems that recall bamboo, and forming stands too thick for anything else to grow.