The question of the difference between Amaryllis and Hippeastrum is a classic case of botanical confusion, stemming from a long and complicated taxonomic history. While the common names are often used interchangeably, from a strict botanical perspective, they refer to distinct genera with key differences.
The most fundamental difference lies in their scientific classification. Both belong to the Amaryllidaceae family, but they are separate genera. The true Amaryllis genus is small, containing essentially one species: Amaryllis belladonna, the Belladonna Lily or Naked Lady. This plant is indigenous to South Africa. In contrast, the genus Hippeastrum is much larger, comprising over 90 species and numerous hybrids. These plants are native to tropical and subtropical regions of the Americas, from Mexico through the Caribbean and down to Argentina.
There are distinct physical characteristics that separate the two. A primary difference is the structure of the flower stem, or scape. The scape of a true Amaryllis belladonna is solid. Conversely, the flower scape of a Hippeastrum is hollow. Their flowers also differ in form. A. belladonna produces clusters of 2-12 fragrant, trumpet-shaped flowers that are typically shades of pink. Hippeastrum cultivars produce larger, often unscented flowers in a vast array of colors and patterns (red, white, orange, pink, striped, etc.), usually in groups of 2 to 4, but sometimes more on larger bulbs.
Their growth and flowering habits are markedly different. Amaryllis belladonna is a perennial that flowers in late summer or autumn. Its most notable trait is that the flowers appear after the foliage has died back, which is why it's called the "Naked Lady." The strap-like leaves grow during the winter and spring and then wither before the flower stalk emerges. Hippeastrum, the common "amaryllis" sold for winter forcing, typically flowers in late winter or spring. Its growth pattern involves the flower stalk emerging first or simultaneously with the growth of new, broad, strap-like leaves, which persist after flowering to help replenish the bulb.
The mix-up began in the 18th century when the Swedish botanist Carl Linnaeus mistakenly placed several New World bulbs in the Old World Amaryllis genus. While the error was later corrected by the botanist William Herbert, who placed the New World bulbs in the new genus Hippeastrum (meaning "Knight's Star"), the common name "amaryllis" had already become firmly entrenched in the horticultural trade and public consciousness for these showy bulbs. This misapplication persists to this day, where "amaryllis" in a gardening context almost always refers to Hippeastrum.
