Native (Mainly) Plant Groups
Maryland Native Plant Society
Virginia Native Plant Society
Virginia Native Plants to Attract Butterflies
VA's Department of Conservation and Recreation's info on Native Plants
National Park Services information about Maryland Natives and here.
University of Maryland's printable booklet about Maryland Natives.
Ladybird Johnson Wildflower Center's info about Maryland Natives and Virginia Natives.
Chesapeake Conservation Landscaping Council (also a water quality group)
Invasive Plants in our Region
Nature Conservancy's info on Invasive Plants in Maryland-DC
University of Maryland on Invasive Species
Invasive Species of Concern in Maryland from the Maryland Invasive Species Council
Maryland Department of Agriculture's info on Invasive Plants
Sierra Club on Invasive Plant Removal
EPA's Invasive Plants of the Mid-Atlantic
Maryland Invasive SPecies Resource Center
USDA's Noxious Weed List for Maryland
Virginia's Dept of Conservation and Recreation on Invasives in Virginia
Water Quality Groups
Anacostia Watershed Society
Chesapeake Bay Foundation
Washington Parks and People
DC Greenworks - specialize in green roofs.