RUSSIAN THISTLE, Solsola koli L. var. tenuifolia Tausch. 1, branch; 2, root; 3, portion of older branch; 4, seed in hull; 5, seed, hull removed. Annual, reproducing by seed. Stem profusely branched, 1 to 3 feet (30 to 90 cm) high, forming typical ball-like tumbleweed at maturity. Young plants soft, succulent; mature plants stiff and woody. Leaves cylindrical or awl-shaped. Young leaves long, soft. Later leaves short, stiff, prickle pointed. Flowers numerous, small, without petals, axillary on upper branches. At maturity, entire plant may be splashed with red color; stem breaks from root and moves freely across open fields with winds scattering the seed. Found in spring grain and legume seedings. An important annual weed, it is most troublesome in dry years.