Annual herbaceous plant of short days, which has an initial maturity cycle between 100 and 120 days, whose height ranges between 30 and 110 cm. The root is cylindrical, pivotal, with a fibrous and shallow branching system. The stem is ridged, smooth or slightly hairy, cylindrical and herbaceous to slightly woody, with resin canals in the bark; it is aromatic when crushed. Leaves opposite at the bottom, alternate at the top, up to 20 cm long, pinnate, composed of 11 to 17 leaflets, serrate, the lower ones of each leaf often setiform (threadlike), the upper ones sometimes completely setiform.