Witch hazel (Hamamelis virginiana) is a deciduous shrub that loses leaves in Winter but, because it sometimes sprouts flowers then, it has the alternate name "winterbloom." From the leaves and bark of this plant come the beauty product witch hazel, obtained from steaming its twigs.

The bark, leaves, and twigs are high in tannins, which offer astringent properties of tightening pores and removing excess oil. It can be used purely as a facial cleanser or with other added ingredients (like aloe vera) for soothing, anti-inflammatory effects. Many witch hazel products today are all natural, lacking artificial ingredients that may overdry or irritate sensitive skin. Hair can benefit, too, as items such as Aveda Witch Hazel Light Hold Hair Spray reduce flyaways and oily scalps.

Source