Multiflora rose: Rosa multiflora Thunbergia ex Murr, is banned in 13 US states, including my own, where it thrives at the expense of native species of many kinds.
Here (at left) it mingles with another invader–Amur honeysuckle (lonicera maackii) along the Tulpehocken Creek in Berks County, Pennsylvania. Amur honeysuckle has not yet made the “illegal plant” list. Both shrubs spread easily because they do not mind disturbed soil and they have attractive berries that birds consume, thus sowing the bushes widely.
I do not know how a plant can be illegal if the birds are our planting culprits; but I do know how hard it is to eradicate multiflora rose, which flourishes in our hedgerow among the sassafras, tulip trees, green ash, white ash, honey locust, wild cherry, walnut, oaks, and maples.
The shrubs are wickedly hard to pull out, as they are stemmy and prickly and have deep roots. We’ve hacked them out of the rocks and pulled them out by chain with our tractor and weed-whacked them and used a machete in the thickets. We have often enlisted our son in our efforts to limit their number along our property line. He refers to the rose as “devil-bush,” having been scourged by its thorns numerous times while endeavoring to cut back or pull out the shrubs. I, too, have shed my blood over its white flowers–not to mention erupted in rashes, because poison ivy frequently entwines itself around the stems of multiflora rose.
Well. They are in bloom now (end of May). And so far, the roses are winning.