Amaryllis belongs to the Amaryllidaceae family and is actually called Hippeastrum. Amaryllis and Hippeastrum are two closely related genera and are often confused. The biggest difference is in the stem. Amaryllis has a massive stem and Hippeastrum a hollow stem. Hippeus means knight and Astrum star, hence the Dutch name Ridderster.
Hippeastrum is nowadays available in many types and colors. Whereas this used to be mainly red and pink, now almost all colors are conceivable. Large-flowered, full-flowered, small-flowered, leguminous and multiflora types have become available in a wide range in recent years.