Hyssop (Hyssopus officinalis) is a shrub of 20-50 (80) cm in height. It has a large ligneous stem root and numerous lignified, woody, tetrahedral, shortly pubescent or bare upright stems that are branched at the base. The leaves are opposite, almost sessile. The flowers are small, located in the axils of the upper leaves, 3-7 each, forming spike-like, often one-sided inflorescences. Calyx is light green, leafy; corolla is of blue, purple, rarely pink color. It blooms in July-September; the fruits ripen in August.