Narrow-leaf pepperwort

Lepidium ruderale, the narrow-leaf pepperwort or roadside pepper-cress, is a slender annual or biennial herb in the family Brassicaceae native to Europe, North Africa, and temperate Asia and now widely naturalized in North America, Australia, and South America. It is a common ruderal of compacted bare ground, trampled pathsides, roadside verges, railway ballast, and saline waste places. Plants reach 10-50 cm in height and emit a strong pungent peppery smell when bruised. The stems are erect, much-branched from near the base, slender, and glabrous to sparsely short-hairy. Basal leaves are once or twice pinnately divided into narrow linear segments and wither early; stem leaves are alternate, simple, linear to narrowly oblong, and entire to slightly toothed. The inflorescence is an elongating slender raceme of very small flowers; petals are absent or extremely reduced so that the four green sepals predominate, with only two stamens (a reduction characteristic of the species). The fruit is a small flat oval silicle 2-3 mm long, slightly notched at the apex, with two single-seeded valves and a short style. Seeds are minute, reddish-brown, and mucilaginous when wetted.