The dark green leaves of Aconitum species lack stipules. They are palmate or deeply palmately lobed with five to seven segments. Each segment again is trilobed with coarse sharp teeth. The leaves have a spiral (alternate) arrangement. The lower leaves have long petioles. The tall, erect stem is crowned by racemes of large blue, purple, white, yellow, or pink zygomorphic flowers with numerous stamens. They are distinguishable by having one of the five petaloid sepals (the posterior one), called the galea, in the form of a cylindrical helmet, hence the English name monkshood. Two to 10 petals are present. The two upper petals are large and are placed under the hood of the calyx and are supported on long stalks. They have a hollow spur at their apex, containing the nectar. The other petals are small and scale-like or nonforming. The three to five carpels are partially fused at the base. The fruit is an aggregate of follicles, a follicle being a dry, many-seeded structure.