Common Burdock – Arctium minus
The survivor will become familiar with common burdock most likely by peeling the bur-like seeds off his or her clothing after fleeing zombies through an overgrown pasture. After removing the burs, though, he or she should stop and take note of the plant.
The taproot of burdock is edible, as is the interior of the stem, and can be collected and cooked. Flour can also be made from the taproot, but that might be tricky in the blender-less future after doomsday. Burdock is a useful plant to know, though, because it grows well in disturbed areas, especially along roadways, paths, railroads, etc., which may be areas a post-apocalyptic survivor would find herself as she wanders the wastelands.
Also, in case society rebuilds itself, a survivor should know that burdock seeds were the initial inspiration for Velcro, and can study the hooks-and-needles form of the hairy burs to reinvent Velcro in a future where humans have learned from their mistakes in the past.
Habitat/plant community: Woodland edges, field edges, savannas, pastures, weedy meadows, along roads and railways, and in waste areas.
Light requirements: Full to partial sun.
Soils: Loamy, fertile soil.
Moisture requirements: Slightly moist to mesic conditions.
Environmental sensitivities: Intolerant to flooding
Functional/design uses: Considered a weed in many settings, but could be planted
Planting techniques: Should not be planted; instead, removed in most garden settings. Spreads by seeding itself, can form colonies of various sizes.
Photos pulled from http://www.co.stevens.wa.us/weedboard/other%20weeds/HTM%20pages/cburdock.htm