Maryland Biodiversity Project, lists plants and other biota and contains links to photos.

Flora of Virginia  The first manual on Virginia plants in 250 years. Published in 2012, featuring 3,164 species, almost 1,600 pages, and 1,400 original illustrations, with keys and excellent habitat information. $96.49 (including S&H).

The Flora of Virginia App puts all the content of the print Flora, and much more, onto your Android or iOS device. $19.99.  Click for Android devices. or Click for iOS devices.

Compare the involucral bracts of sunflowers.  A pictorial guide for identification of Helianthus species.

The Biota of North America Program, from the North Carolina Botanical Garden.

Dr. Duke's Phytochemical and Ethnobotanical Databases, from a scientist at USDA, Agricultural Research Service.

Forest Biology and Dendrology at Virginia Tech, facts on over 450 species of trees.

NatureServe Explorer, a database with information on 50,000 plants, animals, and communities.

PLANTS Database, USDA, Natural Resources Conservation Service.

Lady Bird Johnson Wildflower Center at the University of Texas, Austin, has lots of photos; many plants are western but many have a wide range that includes our area. Search by family name or scientific name and other characteristics.

Southeastern US Plant Identification Resource, created by John. R. Gwaltney, contains many searchable photos of plants of the southeastern US, which include plants in our range.

iNaturalist, "helps you identify the plants and animals around you. Get connected with a community of over 750,000 scientists and naturalists who can help you learn more about nature!" For PC, Mac, iOS, Android.

Seek, "Take your nature knowledge up a notch with Seek! Use the power of image recognition technology to identify the plants and animals all around you. Earn badges for seeing different types of birds, amphibians, plants, and fungi and participate in monthly observation challenges with Our Planet on Netflix."

LeafSnap, an electronic field guide to the trees of the U.S., available for iPhone and iPad.