Snapdragons, known botanically as Antirrhinum majus, are a species of flowering annual that produces large racemes of brightly colored flowers atop tall stems from late spring into fall. The plants grow in full sun to partial shade and are identified before they bloom with a careful inspection of the leaves, stalk and nascent raceme or developing flower head. Snapdragons take their name from the form of the individual ruffled flowers that form along the tip of the stalk. When the flower is pressed from the sides the two hinged ruffled petals open and resemble the head of a dragon opening its mouth.
Observe the foliage tissues of the plant. Snapdragon plants will have a uniform bright to mid-tone green hue. The stalks can be very slightly lighter in green color but the difference between leaf and stalk is not stark.
Look at the leaf architecture. Snapdragon leaves have a central vein that runs on a vertical axis with the leaf relatively smooth on either side of the vein. The leaves take the form of an elongated ovoid or surfboard shape and have a rounded tip that curls under or dips down very slightly.
Inspect the stalks of the plants. Snapdragon stalks range from 6 to 48 inches at maturity and are round in shape, smooth, thick and sturdy and grow stiffly upright from the soil. The leaves branch out horizontally from the stalk and the tip of the stalk is capped by a flower raceme with buds that form a slightly conical shape tapering towards the top.