Crataegus monogyna is environmentally harmful in California and maybe some other states, but it has not been determined to be harmful in Virginia (at least according to the Virginia Department of Conservation and Recreation and the SE-EPPC). If you lived in California, you'd be acting irresponsible (at least by most gardener's standards) by planting this plant. The story is quite different in Virginia.

You probably haven't posted your request in the best forum. This forum is about natives, and Crataegus monogyna is not a native anywhere in North America (which is where most readers of this forum live).

BTW, please do check to see if plants are invasive in your area before choosing to include them in your landscape. Invasives are exponentially-multiplying biological litter. Planting invasives (that are invasive to YOUR state or part of the country) is similar, or worse, to throwing trash out of your car window (except this trash multiplies!). Planting natives is a wonderful thing, but some non-native plants may also be great choices. It's up to you to check whether or not a plant is likely to be an asset or a detriment to your landscape and to the environment.