Stinging Nettle (Urtica dioica)
Despite the fact that stinging nettle can cause skin irritation upon contact with its hairy leaves and stems, this plant can be useful both as a food source and as a medicinal herb. Nettles can often be found in pastures, fields, overgrown yards, waste dumps, roadsides, floodplains, ditches, and along roads, so they should be easily locatable in an overgrowing, abandoned world of the future.
The leaves of stinging nettle can be eaten, and taste somewhat like spinach. Be sure to either soak the leaves in water or cook them before touching them with bare hands or eating them, in order to remove the stinging chemicals.
The leaves are best eaten when young and tender, but if collected anytime between June and September, they can be used for medicinal purposes. As an herb, nettle is an astringent tonic, and can have positive effects in cases of hemorrhages, nosebleeds, diarrhea, dysentery, and fevers. In case you are unfortunately suffering from rheumatoid arthritis or eczema while surviving in the future, nettles can help with those conditions as well.
Of Note to Pre-Apocalyptic Landscape Architect Types:
Leaves grow oppositely on vertical stem, and are serrated with a pointed tip. Leaves and stems are hairy. Flowers are small and brown or green. Grows 1 to 2m tall. Moist fields, forests, or shorelines. Full to partial sun. Prefers moist, rich environments. Does not thrive in phosphorous-deprived soils; prefers nitrogen rich soil. Prefers damp environments. Cannot tolerate saline environments. Often considered a weed, but can be useful in a garden. Nettles make good companion plants to many vegetables including broccoli, tomatoes, mints and other herbs. Can thrive in areas rich in poultry droppings. Cuttings can be used as compost activator (with high nitrogen content). Can be propagated by seed, cuttings, or root division.