Hippeastrum (/ˌhɪpiːˈæstrəm/)[17] is a genus of 116 species,[18] and over 600 hybrids and cultivars, of perennial, herbaceous and bulbous plants, native to tropical and subtropical regions of the Americas, from Mexico south to Argentina and on some islands in the Caribbean.

However, the common name "amaryllis" has been used for Hippeastrum for years, especially for the ornamental cultivars (sold as indoor flowering bulbs around November and December, for Christmas, in the Northern Hemisphere).

Most Hippeastrum bulbs are tunicate (a protective dry outer layer and fleshy concentric inner scales or leaf bases).

The leaves are hysteranthous (develop after flowering), sessile (borne directly from the stem or peduncle), rarely persistent and subpetiolate.

[24] The tepals are united at the base to form a short tube, usually with a rudimentary scaly paraperigonium[25] with fimbriae[26] or a callose ridge present at the throat.

The androecium consists of six stamens with filiform (thread like) filaments, which are fasciculate (in close bundles) and declinate or ascendent.

The fruit forms a trivalve capsule containing seeds which are dry, flattened, obliquely winged or irregularly discoid, hardly ever turgid, and globose (spherical) or subglobose, with a brown or black phytomelanous testa.

However, in 1795 William Curtis, described Amaryllis equestris or the Barbados lily in his Botanical Magazine, referring to Aiton: "The spatha is composed of two leaves, which standing up at a certain period of the plant's flowering like ears, give to the whole flower a fancied resemblance of a horse's head; whether LINNÆUS derived his name of equestris from this circumstance or not, he does not condescend to inform us.

"[33] In 1803 John Sims claimed Curtis had made a mistake in this attribution, and that; "this name was given from the remarkable likeness the front view of it has to a star of some of the orders of knight-hood; an appearance well expressed by JACQUIN's figure in the Hortus Schoenbrunnensis"[34][35]Despite much speculation, there is no definitive explanation of either Linnaeus fils or Herbert's thinking.

[b][42] Linnaeus had earlier worked on the Estate of George Clifford near Haarlem between 1735 and 1737 describing the plants growing there in his Hortus Cliffortianus in 1738.

This paper sparked a debate over the next half century, that delayed the official transfer of species from Amaryllis to Hippeastrum.

[57] Baker both reduced the original number of species of Herbert, but also enlarged the genus by adding in other genera such as Habranthus, Phycella, Rhodophiala and Rhodolirion (also called Rhodolirium, and subsequently moved to Rhodophilia),[58] which he included as separate sections of Hippeastrum.

[63] Unplaced names include Hippeastrum ugentii,[64] considered in the Kew World Checklist of Selected Plant Families as probably a Crinum.

[29] Their habitat is mainly tropical and subtropical, though those species found south of the equator, or at sufficient altitude may be considered temperate.

[80] The bulb is tender and should not be exposed to frost, but is otherwise easy to grow with large rewards for small efforts, especially those that bloom inside during the winter months.

Summering outdoors in four or five hours of direct sunlight, plus fertilizing lightly as the season progresses, will help develop buds for the next year.

[80] Intense cultivation of a number of species, particularly from Brazil, Bolivia and Peru, has occurred because of the appearance and size of the flowers, resulting in many hybrids and cultivars.

[53][65] Leopoldii hybrids arose from the work of the British explorer and botanist Richard Pearce, an employee of James Veitch & Sons, a plant nursery.

[53][65][85] The late 19th and early 20th centuries saw Amaryllis breeding develop in the United States, particularly in Texas, California, and Florida in conjunction with the USDA (1910–1939).

[31][72] Most modern commercial hybrids are derived from the following species:[73] Three main methods are used for propagating Hippeastrum: seeds, bulbils and 'twin scales'.

[65] Hippeastrum hybrids and cultivars are valued for their large ornamental flowers, particularly for indoor cultivation during the northern hemisphere winter.

A bulb needs to produce large, healthy leaves in the summer growing season before it can send up a scape the following year.

Dutch bulbs usually produce flowers first, then, after they have finished blooming (hysteranthous), the plant will begin growing leaves.

Single, double, and miniature bulbs are the ones typically sold by nurseries and other stores for the holidays in December and for St. Valentine’s Day and Easter.

[92][93] Hippeastrum bulbs can be induced to rebloom yearly by mimicking the conditions in its natural environment (cool dry winters).

Even when plants are thriving outdoors in temperate climates, dormancy can be induced by withholding water and fertilizer in the northern hemisphere autumn, and bringing indoors to a cool environment prior to the first frost.

[52][72][74][94] The cultivar 'Clown' (Double Galaxy Group)[95] (white with red stripes) has received the Royal Horticultural Society's Award of Garden Merit.

Cultivars of Hippeastrum are popular indoor ornamental plants prized for their large brightly colored flowers (including red, pink, salmon, orange and white).

Although the market is dominated by the Netherlands,[73] and South Africa,[53] other areas of production include Israel, Japan and the United States (Florida).

The leaves represent the protection, purpose, growth and development of the Huntington's community worldwide in its search for a cure and treatment.