Amaryllis is a plant genus containing one species, the Belladonna Lily (Amaryllis belladonna), a native of South Africa. It is a bulb plant, with a bulb 5-10 cm diameter. It has several strap-shaped, dull green leaves, 30-50 cm long and 2-3 cm broad, arranged in two rows. The leaves are produced in the autumn and eventually die down by late spring and the bulb is then dormant until late summer, when it produces one or two naked stems 30-60 cm tall, each bearing at the top a cluster of 2 to 12 funnel-shaped flowers. Each flower is 6-10 cm diameter, with six tepals (three outer sepals, three inner petals, with similar appearance to each other), white, pink or purple in colour. This flowering pattern is the cause of its common name 'naked lady'. The scientific name Amaryllis is named after a shepherdess in classical Greek poetry.

The Belladonna Lily was introduced into cultivation at the beginning of the 18th century. However, most of the so-called Amaryllis sold as 'ready to bloom for the holidays' bulbs belong to the allied genus Hippeastrum, despite being labeled as "Amaryllis" by sellers and nurseries. Continuing the theme of name confusion, bulbs of other species with a similar growth and flowering pattern are also sometimes called 'naked ladies', even though those species have their own more widely used and accepted common names, such as 'Resurrection Lily' for Lycoris squamigera.