Invasive species currently associated with the most severe degradation of native biodiversity in the Crum Woods are:

    Norway maple (Acer platanoides)

    English ivy (Hedera helix)

    three herbaceous species:
        garlic-mustard (Alliaria petiolata)
        Japanese knotweed (Polygonum cuspidatum)
        lesser celandine (Ranunculus ficaria)

    A host of other invasive species as a group significantly reduce
biodiversity in the Crum Woods, and any one might be on the verge of
graduating to a severe problem species.  They include:

the trees:
    tree-of-heaven (Ailanthus altissima)
    royal paulownia (Paulownia tomentosa)
    Japanese cork-tree (Phellodendron japonicum)
woody vines:
    akebia (Akedia quinata)
    Asiatic bittersweet (Celastrus orbiculatus)
    Japanese honeysuckle (Lonicera japonica)
the upright shrubs:
    burning-bush (Euonymus alatus)
    common privet (Ligustrum vulgare)
    California privet (Ligustrum ovalifolium)
    Amur honeysuckle (Lonicera maackii)
    multiflora rose (Rosa multiflora)
    sapphire-berry (Symplocos paniculata)
    doublefile viburnum (Viburnum plicatum)
the prostrate shrubs:
    Japanese spurge (Pachysandra terminalis)
    periwinkle (Vinca minor)
the herbs:
    goutweed (Aegopodium podagraria)
    common reed (Phragmites australis)