National Capital Parks-East - Nonnative Species

Of the 1026 species of vascular plants documented from National Capital Parks-East (NACE) 26.6 percent are species not native to Maryland or the District of Columbia. Only a few of these are actually invasive (displacing our native plant species). Non-native invasive aquatic species include Hydrilla (Hydrilla verticillata) and Eutrophic Water-nymph (Najas minor). Species invasive in wetlands include Dew Flower (Murdannia keisak), Common Reed (Phragmites australis), and Purple Loosestrife (Lythrum salicaria). Plants that are invasive in upland areas include vines such as Oriental Bittersweet (Celastrus orbiculatus), Japanese Honeysuckle (Lonicera japonica), English Ivy (Hedera helix), Japanese Wisteria (Wisteria floribunda), and Yam-leaved Clematis (Clematis terniflora). Other upland invasives are grasses such as Japanese Stilt-grass (Microstegium vimineum), Sweet Vernal Grass (Anthoxanthum odoratum) and Tall Fescue (Festuca elatior), shrubs such as Bush Honeysuckle (Lonicera maackii) and herbaceous plants such as Ivy-leaved Speedwell (Veronica hederaefolia), Garlic-mustard (Alliaria petiolata), and Beefsteak Mint (Perilla frutescens). Less is known about the impacts of non-native animals within NACE but the worst offenders may be the feral domestic cats that impact the wild bird and small mammal populations within NACE.