Flax (Linum usitatissimum) is an annual herb. The root is rather short, whitish with a few larger primary branches. Stem is 60-120 (150) cm tall, mostly erect and straight, thin, cylindrical. The leaves are quite numerous, relatively spirally arranged, 2-3 cm long, 3-4 mm wide. The flowers are few in number, mostly of medium size or rather small, 1.5-2.4 cm in diameter. Petals are 12-15 mm long, wedge-obovate. The fruit is a capsule 6-8 mm long, 5.7-6.8 mm in diameter, flattened-spherical or spherical-ovate. Seeds are usually 10, sometimes less, 3.3-5 mm long, ovate or elongated-elliptical, somewhat unequal, strongly flattened, rounded at the base, pointed at the top, light brown to dark brown, occasionally greenish-yellow, perfectly smooth, shiny.