Stems: erect, simple. Leaves: oblanceolate or linear, obtuse, entire or dentate, the upper sessile, the lower slender-petioled. Flowers: pale yellow. Fruit: the siliques elongated, linear, four-angled, valves strongly keeled by a prominent mid-vein.
This common Treacle Mustard has very small pale yellow flowers and rather whitish leaves, which latter grow in a tuft at the base of the plant and also alternately all the way up the stiff erect stems. The flowers have four tiny green sepals and four yellow petals, which latter are cruciate, or set in the form of a cross. The Treacle Mustard belongs to the Cruciferce, or Mustard Family, all of whose members have four cruciform petals.