Few seed become established in turf with as little notice as knawel. This tough little annual starts growth in very early spring and its grass-like features make it very inconspicuous. It lies close to the ground, spreads and avoids the blades of the sharpest mower. Leaves are awl-shaped and sharp pointed . They are opposite each other on spreading branches. Flowers are small, green and spiny to the touch. Their outer leaves form a cup that holds the seed. This plant is found from Canada to Minnesota, along the Eastern states to Florida and occasionally in the Pacific Northwest. It is most troublesome in the mid-atlantic states.