Hollyhock (Alcea rosea) is a large, fast-growing biennial plant in the Malvaceae family. Typical of country gardens, it blooms from late spring to summer, or even early fall, in very large flowers with simple corollas formed of 1.1 to 1.9 inches (3 to 5 cm) petals in varied colors. The darker their color, the greater their concentration of pigments, tannins, and medicinal properties.