|A Hippeastrum cultivar in flower|
Hippeastrum // is a genus of about 90 species and over 600 hybrids and cultivars of perennial herbaceous bulbous plants. They generally have large fleshy bulbs and tall broad leaves, generally evergreen, and large red or purple flowers.
Hippeastrum is a genus in the family Amaryllidaceae (subfamily Amaryllidoideae, tribe Hippeastreae, and subtribe Hippeastrineae)  The name Hippeastrum was derived from the common name given to it by William Herbert of "Knight's-star-lily". For many years there was confusion among botanists over the generic names Amaryllis and Hippeastrum, one result of which is that the common name "amaryllis" is mainly used for cultivars of this genus, often sold as indoor flowering bulbs particularly at Christmas in the northern hemisphere. By contrast the generic name Amaryllis applies to bulbs from South Africa, usually grown outdoors. The genus is native to tropical and subtropical regions of the Americas from Argentina north to Mexico and the Caribbean.
Reproduction is generally by allogamy (cross-pollination) and Hippeastrum may be propagated by seed or offset bulbils (bulblets), although commercial ventures use in vitro techniques, or splitting of the bulb into sections. The genus has been intensely bred and cultivated since the early nineteenth century to produce large colourful showy flowers. In temperate climes these can be placed outside in the summer, and after a dormancy period, be induced to rebloom inside in the winter.
- 1 Description
- 2 Taxonomy
- 3 Distribution and habitat
- 4 Ecology
- 5 Breeding and propagation
- 6 Conservation
- 7 Cultivation
- 8 Uses
- 9 Culture
- 10 Species
- 11 Synonyms
- 12 Intergeneric hybrids
- 13 References
- 14 See also
- 15 Bibliography
- 16 External links
Most Hippeastrum bulbs are tunicate (a protective dry outer layer and fleshy concentric inner scales or leaf bases). The bulbs are generally between 5–12 cm (2"–5") in diameter and produce two to seven long-lasting evergreen or deciduous leaves that are 30–90 cm (12"–36") long and 2.5–5 cm (1"–2") wide. The leaves are hysteranthous (develop after flowering), sessile, rarely persistent and subpetiolate.
The flowers are arranged in umbelliform inflorescences which are pauciflor or pluriflor (2-14 flowers), supported on an erect hollow scape (flower stem) which is 20–75 cm (12"–30") tall and 2.5–5 cm (1"–2") in diameter with two free bracts forming a spathe which is bivalve with free leaflets at its base. Depending on the species, there are two to fifteen large showy flowers, which are more or less zygomophic and hermaphrodite. Each flower is 13–20 cm (5"–8") across, and the native species are usually purple or red. They are funnelform (funnel shaped) and declinate (curving downwards and then upwards at the tip) in shape. The perianth has six brightly colored tepals (three outer sepals and three inner petals) that may be similar in appearance or very different. The perianth segments are subequal or unequal. The tepals are united at the base to form a short tube, usually with a rudimentary scaly paraperigonium with fimbriae 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 anthers are dorsifixed or versatile. In the gynaecium, the ovary is inferior and trilocular with pluriovulate locules. The style is filiform, and the stigma trifid. 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. 
Separation of Hippeastrum from Amaryllis
The taxonomy of the genus is complicated. The first issue is whether the name should more properly be Amaryllis L.. In 1753 Carl Linnaeus created the name Amaryllis belladonna, the type species of the genus Amaryllis, in his Species Plantarum along with eight other Amaryllis species. 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. It is to this work that he refers in his Species Plantarum. This was assumed to be the South African Cape Belladonna, although not precisely known. Clifford's herbarium is now preserved at the Natural History Museum in London.
At the time both South African and South American plants were placed in this same genus. By the early nineteenth century Amaryllis had become a polymorphic (diverse) genus with about 50 species from what we would consider a dozen genera today, and attempts were made to separate it into separate genera. This work commenced in 1819 with the contributions of the English botanist, the Revd. William Herbert in Curtis's Botanical Magazine  which he expanded in 1821 in The Botanical Register, identifying 14 species of the new genus of Hippeastrum, and only leaving three species in Amaryllis. The rest of the Amaryllis species he transferred to other genera, several of which he created.
Since then a key question has been whether Linnaeus's original type was a South African plant (now Amaryllis) or a South American plant (now Hippeastrum). If the latter, the correct name for the genus Hippeastrum would then be Amaryllis and a new name would need to be found for the South African genus. In 1938 JCT Uphof claimed, with some evidence, that the plant was in fact the South American Hippeastrum equestre (Linn. fil.) Herb. (syn. Amaryllis equestris (Linn. fil.) ex Aiton, accepted name H. puniceum) a plant which Carl Linnaeus' son, Linnaeus the Younger (Linn. fil.) had described c. 1781-3 (unpublished) but soon after appearing in the Hortus Kewensis of 1789. This paper sparked a debate over the next half century, that delayed the official transfer of species from Amaryllis to Hippeastrum. This debate involved botanists on both sides of the Atlantic and the final outcome was a decision by the 14th International Botanical Congress in 1987 that Amaryllis L. should be a nomen conservandum (conserved name, i.e. correct regardless of priority) and ultimately based on a specimen of the South African Amaryllis belladonna from the Clifford Herbarium. Thus Amaryllis L. is the correct name for the South African genus, not the South American genus (Hippeastrum).
Claim for Leopoldia
The second issue is whether the name should be Leopoldia. In 1819 Herbert had proposed Leopoldia as a nomen provisorium (provisional name) for the same taxon as he called Hippeastrum in 1821. Although Leopoldia was subsequently validated (i.e. became the correct name), this was overlooked, and Hippeastrum rather than Leopoldia was used for the genus of New World amaryllids. Following Filippo Parlatore in 1845, the name Leopoldia was used for a genus of grape hyacinth species, allied to Muscari. In order to preserve the widespread usage of both Hippeastrum and Leopoldia, Fabio Garbari and Werner Greuter proposed in 1970 that Herbert's Hippeastrum and Parlatore's Leopoldia should be conserved and Herbert's Leopoldia rejected. This was accepted and Hippeastrum Herb. is now a conserved name (nomen conservandum), i.e. the correct name regardless of the fact that it does not have priority over Leopoldia.
- Aschamia (Salisb.) Baker (e.g. H. reginae)
- Cephaleon Traub (e.g. H. machupijchense)
- Lais (Salisb.) Baker (e.g. H. striatum)
- Macropodastrum Baker (e.g. H. elegans)
- Omphalissa (Salisb.) Baker (e.g. H. aulicum)
- Sealyana Traub (e.g.: H. reticulatum)
Although the 1987 decision settled the question of the scientific name of the genus, the common name "amaryllis" continues to be used. Bulbs sold as amaryllis and described as ready to bloom for the holidays belong to the genus Hippeastrum. "Amaryllis" is also used in the name of some societies devoted to the genus Hippeastrum. Separate common names are used to describe the genus Amaryllis, e.g. "Naked Lady".
The name Hippeastrum was first given to the genus by Herbert, being derived from the Greek,  meaning a "Knight's Star" from ἱππεύς (hippeus, mounted knight) and ἄστρον (astron, star), to describe the first recognized species, Hippeastrum reginae. Herbert proposed to call the genus, which he distinguished from Linnaeus' Amaryllis, Hippeastrum, or "Knight's-star-lily". He states;
"I have named [them] Hippeastrum or Knights-star-lily, pursuing the idea which gave rise to the name Equestris" (p.12).
Herbert's fourteen species included this Hippeastrum equestre. This 'equine' connection refers to Carl Linnaeus the Younger who had named (in an unpublished manuscript) a West Indian species as Amaryllis equestris Linn. fil., because of its similarity to the African genus Amaryllis. This name and attribution was first published by William Aiton in 1789, in his Hortus Kewensis. Which species this was is not known precisely. 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."
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 JAQUIN's figure in the Hortus Schoenbrunnensis"
Despite much speculation, there is no definitive explanation of either Linnaeus fils or Herbert's thinking. For instance the 'Knight's Star' has been compared to Linnaeus' decoration as a Knight of the Order of the Polar Star. The Latin word equestris (of a knight, or horseman) may have been confused with equi (of a horse), or possibly Herbert was making a literary Knight's Move on the Linnaean term. The flower name has even been compared to the mediaeval weapon, the spoked mace or Morning Star which it superficially resembles.
Distribution and habitat
Hippeastrum species are concentrated in two centres of diversity, the main one in Eastern Brazil and the other in the central southern Andes of Peru, Bolivia and Argentina, on the eastern slopes and nearby foothills. Some species are found as far north as Mexico and the West Indies. The genus is thought to have originated in Brazil where at least 34 of the species have been found. Their habitat is mainly tropical and subtropical, though those species found south of the equator, or at sufficient altitude may be considered temperate. Hippeastrum is found in a wide range of habitats. Many are found in underbrush, while others prefer full sun. Hippeastrum angustifolium is an example of a species preferring flood areas, while other species prefer a drier habitat. There are also epiphytic species such as Hippeastrum aulicum, Hippeastrum calyptratum, Hippeastrum papilio and Hippeastrum arboricola, which require air circulation around their roots.
Hippeastrum hybrids and cultivars are valued for their large ornamental flowers, particularly for indoor cultivation during the northern hemisphere winter. The larger the bulb, the more flowers it will produce. The largest bulbs measure 14 to 16 inches (36 to 41 cm) in circumference and will produce three or more scapes (flower stems) with four or more blooms each. The commonest bulbs measure 10½ to 12½ inches (27 to 32 cm) with two scapes with four to six flowers each depending on the cultivar. Some bulbs put up two flower scapes at the same time; others may wait several weeks between blooms and sometimes the second scape will have only two or three flowers rather than the usual four. A bulb needs to produce large, healthy leaves in the summer growing season before it can send up a scape the following year. Bulbs are often described by the country of origin of the bulb producers, since they may have different characteristics, e.g. 'Dutch Amaryllis', 'South African Amarylllis'. Dutch bulbs usually produce flowers first, then, after they have finished blooming (hysteranthous), the plant will begin growing leaves. Bulbs from the South African growers usually put up a scape and leaves at the same time (synanthous).
Of the many hybrids, the best known are those producing flowers with red, pink, salmon, orange and white colors. Other flower colors include yellow and pale green with variations on these including multicoloring, with different colored mottling, stripes or edges on the petals. Some flowers have uniform colors or patterns on all six petals while others have more pronounced colors on the upper petals than on the lower ones.
Although many names are used to describe the plants, e.g. 'Large Flowering', 'Dutch', 'Royal Dutch', there are five types that are commonly sold;
- 1) Single flower (large flowering)
- 2) Double flower
- 3) Miniature (dwarf)
- 4) Trumpet
- 5) Jumbo (mammoth).
'Trumpets', as the name suggests, have flared, tube-shaped flowers. Single, double, and miniature bulbs are the ones typically sold by nurseries and other stores for the holidays in December and for Valentine's Day and Easter.
Of the Hippeastrum species, Hippeastrum cybister has extremely thin petals often described as spider-like. The miniature evergreen Hippeastrum papilio (so named because it resembles a butterfly) has a unique color and pattern with broad rose-burgundy center stripes and striations of pale green on the upper petals and narrow stripes on the bottom three. It has been crossed with both cybister and single flower cultivars to produce hybrids with unusual striping.
Species are generally diploid with 2n=22 chromosomes, but some species, e.g. Hippeastrum iguazuanum have 24. The genus has a high degree of intercompatibility allowing crossing. Seedlings will flower in 3 to 5 years.
Some species, such as the Uruguayan Hippeastrum petiolatum, are sterile and unable to produce seeds. H. petiolatum is a sterile triploid that reproduces asexually, producing many bulbils around the mother bulb. These are light, and easily carried on the surface of water ensuring distribution of the species during the rainy season. Other species such as Hippeastrum reticulatum are self-pollinating, reproducing by distributing seed. Although this does not guarantee genetic diversity in natural populations, it is widely used by colonising species. These two examples are not however typical of the genus, which commonly reproduces through allogamy. One mechanism that limits self-pollination is that of self-incompatibility by which seeds are only produced by pollination from other plants. Furthermore the plant generally releases its pollen about two days before its stigma is receptive, making cross-pollination more likely. Pollinators include Humming birds in subtropical areas, and moths.
Hippeastrum species are used as food plants by the larvae of some Lepidoptera species including Spodoptera picta (Crinum grub)  as well as Pseudococcidae (Mealybugs), large, and small narcissus bulb flies (Eumerus strigatus and E funeralis), thrips, mites, aphids, snails and slugs. A fungal disease attacking Hippeastrum is Stagonospora curtisii (red blotch, red leaf spot or red fire).
Breeding and propagation
Hippeastrum breeding began in 1799 when Arthur Johnson, a watchmaker in Prescot, England, crossed Hippeastrum reginae with Hippeastrum vitattum, obtaining hybrids that were later given the name Hippeastrum × 'Johnsonii' (Johnson's amaryllis, 'hardy amaryllis' or St. Joseph's lily). Johnson shared his work with the Liverpool Botanic Garden which was fortunate, since his greenhouse was destroyed in a fire. His hybrid was being cultivated in the US by the mid-nineteenth century. Many new hybrid lines followed as new species were sent to Europe from South America, the most important of which were Reginae and Leopoldii.
The Reginae strain hybrids were produced by Jan de Graaff and his two sons in the Netherlands in the mid 19th century by crossing Hippeastrum vitatum and Hippeastrum striatum with Hippeastrum psittacinum and some of the better hybrids available in Europe at the time. Some of the most successful hybrids were Graveana and Empress of India.
Leopoldii hybrids arose from the work of the British explorer and botanist Richard Pearce, an employee of James Veitch & Sons, a plant nursery. Pearce brought back specimens of Hippeastrum leopoldii and Hippeastrum pardinum from the Andes. These two species were notable for large flowers that were wide open and relatively symmetrical. Crossing these two species with the best of the Reginae strain produced a lineage of very large open flowered specimens, with up to 4-6 flowers on each scape. The Veitch nursery dominated the commercial development of Hippeastrum leopoldii and other varieties up to the early years of the twentieth century, the best of their hybrids setting the standard for modern commercial development.
In the late 19th and early 20th century saw amaryllis breeding develop in the United States, particularly in Texas, California, and Florida in conjunction with the USDA (1910–1939). The major US contribution came from the work of Henry Nehrling and Theodore Mead, whose hybrids crossed with Dutch stock have produced some modern hybrids, although not matching the European strains.
In 1946 two Dutch growers moved to South Africa and began cultivation there. Although most cultivars of Hippeastrum come from the Dutch and South African sources, bulbs are now being developed in the United States, Japan, Israel, India, Brazil and Australia. The double flowers from Japan are particularly beautiful. Nurseries may list Amaryllis bulbs as being 'Dutch', 'Israeli', 'Peruvian' etc., depending on the country of origin.
Most modern commercial hybrids are derived from the following species:
• H. vittatum
• H. leopoldii
• H. pardinum
• H. reginae
• H. puniceum
• H. aulicum
Three main methods are used for propagating Hippeastrum; seeds, bulbils and 'twin scales'. More recently micropropagation in vitro has been used on a commercial scale.
Seed multiplication may be used for the development of new cultivars or to increase the yield of native species. Seeds are generally sown in early summer in seedbeds, and then transplanted to larger containers. They require warmth frequent watering, and should not be given a dormant period. Seeds do not breed true. Plants obtained from seeds take about 6 years to bloom. 
Home propagation is best performed by using offset bulbils. Commercially, only cultivars that produce at least three bulbils on the mother bulb are used for this form of propagation. Plants grown from this method take 3–4 years to bloom.
The commonest commercial propagation method is referred to as 'twin scales'. This involves the division of the bulb into 12 sections and then separating each section into twin scales connected by the basal plate. The cuttings that are derived from these are grown in moist vermiculite in the dark till bulbils appear. More recently growing them in sunlight produce a better crop.
The technique of plant tissue culture in vitro improves the propagation of Hippeastrum by decreasing the time required to reach the minimum size to start the reproductive cycle, using sections of bulbs grown in artificial media with the addition of plant hormones.
Most modern cultivars lack any fragrance. 'Dancing Queen' represents an exception. (Radescu 2012) Fragrance is genetically related to flower colour (white, or pastel shades) and is a recessive characteristic, so that when fragrant and non fragrant varieties are crossed, not all progeny will be fragrant, whereas two fragrant progenitors will produce an all fragrant progeny.
- Hippeastrum arboricolum Ravenna (Argentina)
- Hippeastrum aviflorum Ravenna (Argentina)
- Hippeastrum canterai Arechavaleta (Uruguay)
- Hippeastrum ferreyrae (Traub.) Gereau & Brako (Peru)
- Hippeastrum petiolatum Pax (Argentina & Brasil)
Hippeastrum cultivars and species can be grown inside in pots or outside in warmer climates (Hardiness 7B-11). Many will bloom year after year provided they are given a dormant period in a cool, dark place for two months without water or fertilizer although some bulbs will start growing before the two-month period is up.
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. Note too, that Hippeastrum can also be grown in the ground in temperate areas. Bulbs are usually sold in fall for early winter bloom. Bare-root bulbs should be planted in a pot only slightly larger than the circumference of the bulb in well-drained, organic mix (such as sterilized potting soil plus coir fiber, or equal amounts of peat moss, sand and humus), with one third of the bulb visible above the surface of the soil and two thirds buried.
After planting, the pot should be placed in a warm place as sprouting requires about 20°C. Bulbs need light watering until the leaves and buds emerge, and then should be situated in a well-lit, cool place and watered as needed to maintain moderate soil moisture. Overwatering will cause bulb and root rot. Plants may be fed with common fertilizers that contain iron and magnesium. Blooming takes place about two months after planting. The plants leaves should continue to grow after the flowers have faded. 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.
When foliage starts to yellow, one should start withholding water, and bulbs should be placed in cool (4-13°C) dark place for six to ten weeks or until buds start to show. Bulbs should be brought back into light, inspected for pests or rot, and repotted in fresh soil. Foliage should be cut to about 10 cm above the bulb. Bulbs should preferably be transplanted every three to four years. Subsequent care is as for new bulbs, as described above.
Cultivars and hybrids
|Diversity of cultivars|
Cultivars of Hippeastrum are popular indoor ornamental plants prized for their large brightly colored flowers (including red, pink, salmon, orange and white). As such they have a very important place in the floriculture trade for sale as cut flowers or potted plants. Although the market is dominated by the Netherlands, and South Africa. Other areas of production include Israel, Japan and the United States (Florida). Brazil also produces 17 million Hippeastrum bulbs annually.(Kamenetsky and Okubo, 442)
Hippeastrum has yielded at least 64 isoquinoline alkaloids, which include anti-parasitic (e.g. candimine) and psychopharmacological activity. Due to their high alkaloid content, One alkaloid isolated from Hippeastrum vittatum (montanine) has demonstrated antidepressant, anticonvulsant and anxiolytic properties. Hippeastrum puniceum may also have therapeutic properties as it has been used in folk medicine to treat swellings and wounds.
A stylized flower of a Hippeastrum cultivar (under its common name of amaryllis) is used internationally as a symbol for organizations associated with Huntington's disease, a genetic degenerative disease of the nervous system. The widely used logo represents a double image of a head and shoulders as the flower of a growing and vibrant plant. The reduced size of the inner head and shoulders image symbolizes the diminution in a person caused by Huntington's disease. The leaves represent the protection, purpose, growth and development of the Huntington's community worldwide in its search for a cure and treatment.
- Hippeastrum aglaiae (A.Cast.) Hunz. & A.A.Cocucci
- Hippeastrum amaru (Vargas) Meerow
- Hippeastrum andreanum Baker
- Hippeastrum angustifolium Pax
- Hippeastrum anzaldoi (Cárdenas) Van Scheepen
- Hippeastrum apertispathum (Traub) H.E.Moore
- Hippeastrum arboricola (Ravenna) Meerow
- Hippeastrum argentinum (Pax) Hunz.
- Hippeastrum aulicum (Ker Gawl.) Herb.
- Hippeastrum aviflorum (Ravenna) Dutilh
- Hippeastrum blossfeldiae (Traub & J.L.Doran) Van Scheepen
- Hippeastrum brasilianum (Traub & J.L.Doran) Dutilh
- Hippeastrum breviflorum Herb.
- Hippeastrum bukasovii (Vargas) Gereau & Brako
- Hippeastrum caiaponicum (Ravenna) Dutilh
- Hippeastrum calyptratum (Ker Gawl.) Herb.
- Hippeastrum canterai Arechav.
- Hippeastrum caupolicanense (Cárdenas) Van Scheepen
- Hippeastrum chionedyanthum (Cárdenas) Van Scheepen
- Hippeastrum condemaitae (Vargas & E.Pérez) Meerow
- Hippeastrum correiense (Bury) Worsley
- Hippeastrum crociflorum Rusby
- Hippeastrum curitibanum (Ravenna) Dutilh
- Hippeastrum cuzcoense (Vargas) Gereau & Brako
- Hippeastrum cybister (Herb.) Benth. ex Baker
- Hippeastrum damazianum Beauverd
- Hippeastrum divijulianum (Cárdenas) Meerow
- Hippeastrum doraniae (Traub) Meerow
- Hippeastrum elegans (Spreng.) H.E.Moore
- Hippeastrum escobaruriae (Cárdenas) Van Scheepen
- Hippeastrum espiritense (Traub) H.E.Moore
- Hippeastrum evansiae (Traub & I.S.Nelson) H.E.Moore
- Hippeastrum ferreyrae (Traub) Gereau & Brako
- Hippeastrum forgetii Worsley
- Hippeastrum fragrantissimum (Cárdenas) Meerow
- Hippeastrum fuscum Kraenzl.
- Hippeastrum gertianum (Ravenna) Dutilh
- Hippeastrum glaucescens (Mart. ex Schult. & Schult.f.) Herb.
- Hippeastrum goianum (Ravenna) Meerow
- Hippeastrum guarapuavicum (Ravenna) Van Scheepen
- Hippeastrum harrisonii (Lindl.) Hook.f.
- Hippeastrum hemographes (Ravenna) Dutilh
- Hippeastrum hugoi (Vargas) Gereau & Brako
- Hippeastrum iguazuanum (Ravenna) T.R.Dudley & M.Williams
- Hippeastrum incachacanum (Cárdenas) Van Scheepen
- Hippeastrum intiflorum (Vargas) Gereau & Brako
- Hippeastrum kromeri (Worsley) Meerow
- Hippeastrum lapacense (Cárdenas) Van Scheepen
- Hippeastrum leonardii (Vargas) Gereau & Brako
- Hippeastrum leopoldii T.Moore
- Hippeastrum leucobasis (Ravenna) Dutilh
- Hippeastrum macbridei (Vargas) Gereau & Brako
- Hippeastrum machupijchense (Vargas) D.R.Hunt
- Hippeastrum mandonii Baker
- Hippeastrum maracasum (Traub) H.E.Moore
- Hippeastrum marumbiense (Ravenna) Van Scheepen
- Hippeastrum miniatum (Ruiz & Pav.) Herb.
- Hippeastrum mollevillquense (Cárdenas) Van Scheepen
- Hippeastrum monanthum (Ravenna) Meerow
- Hippeastrum morelianum Lem.
- Hippeastrum nelsonii (Cárdenas) Van Scheepen
- Hippeastrum oconequense (Traub) H.E.Moore
- Hippeastrum papilio (Ravenna) Van Scheepen
- Hippeastrum paquichanum (Cárdenas) Dutilh
- Hippeastrum paradisiacum (Ravenna) Meerow
- Hippeastrum paranaense (Traub) Meerow
- Hippeastrum pardinum (Hook.f.) Dombrain
- Hippeastrum parodii Hunz. & A.A.Cocucci
- Hippeastrum petiolatum Pax
- Hippeastrum pilcomaicum (Ravenna) Meerow
- Hippeastrum psittacinum (Ker Gawl.) Herb.
- Hippeastrum puniceum (Lam.) Voss. Syn. H. equestre (Aiton)
- Hippeastrum reginae (L.) Herb.
- Hippeastrum reticulatum (L'Hér.) Herb. Syn H. striatifolium (Sims)
- Hippeastrum rubropictum (Ravenna) Meerow
- Hippeastrum santacatarina (Traub) Dutilh
- Hippeastrum scopulorum Baker
- Hippeastrum starkiorum (I.S.Nelson & Traub) Van Scheepen
- Hippeastrum striatum (Lam.) H.E.Moore
- Hippeastrum stylosum Herb.
- Hippeastrum teyucuarense (Ravenna) Van Scheepen
- Hippeastrum traubii (Moldenke) H.E.Moore
- Hippeastrum umabisanum (Cárdenas) Meerow
- Hippeastrum vanleestenii (Traub) H.E.Moore
- Hippeastrum variegatum (Vargas) Gereau & Brako
- Hippeastrum viridiflorum Rusby
- Hippeastrum vittatum (L'Hér.) Herb.
- Hippeastrum wilsoniae L.J.Doran & F.W.Mey.
- Hippeastrum yungacense (Cárdenas & I.S.Nelson) Meerow
The following generic names are synonymous with Hippeastrum:
- Amaryllis L. 1753
- Leopoldia Herb. 1821. nom. rejic.
- Trisacarpis Raf. 1836
- Aschamia Salisb. 1866
- Lais Salisb. 1866
- Omphalissa Salisb. 1866.
- Lepidopharynx Rusby 1927
- Moldenkea Traub 1951
While interspecific hybrids of Hippeastrum are relatively common, hybridization with other genera of Amaryllidaceae are more rare. The most conspicuous exception is the hybrid obtained through crossbreeding with the Mexican Sprekelia formosissima Herb. (St James's lily, Aztec lily, Jacobean lily), another member of the tribe Hippeastreae, originally called Amaryllis formosissima, which is apomictic. × Hippeastrelia is the name given to this cross. 
- New Sunset Western Garden Book, Oxmoor House 2012. ISBN 978-0-376-03921-7
- Stevens, P.F. (2001 onwards). "Angiosperm Phylogeny Website: Asparagales: Amaryllidoideae". Missouri Botanical Garden. Retrieved 2013-11-26.
- "Hippeastrum". Flora of North America. Retrieved 2013-12-19.
- Dimitri, M. (1987). Enciclopedia Argentina de Agricultura y Jardinería. Tomo I. Descripción de plantas cultivadas (in Spanish). Buenos Aires: Editorial ACME S.A.C.I.
- "Funnel shaped". Kew Glossary. Retrieved 2013-12-01.
- "Declinate". Kew Glossary. Retrieved 2013-12-01.
- Global Plants "Entry for Hippeastrum Herb.". JSTOR Global Plants. Retrieved 2013-12-20.
- Alan W. Meerow, Michael F. Fay, Charles L Guy, Qin-Bao Li, Faridah Q Zaman, Mark W. Chase. Systematics of Amaryllidaceae based on cladistic analysis of plastid sequence data. Am. J. Bot. September 1999 vol. 86 no. 9 1325-1345
- "Fimbriae". Kew Glossary. Retrieved 2013-12-06.
- Michael G. Simpson. Plant Systematics. Academic Press, 2011 ISBN 0-08-051404-9, 9780080514048 accessed December 1, 2013
- "Pluriovulate". Kew Glossary. Retrieved 2013-12-01.
- de Andrade, Jean Paulo; Belén Pigni, Natalia; Torras-Claveria, Laura; Guo, Ying; Berkov, Strahil; Reyes-Chilpa, Ricardo; El Amrani, Abdelaziz; Zuanazzi, José Angelo S.; Codina, Carles; Viladomat, Francesc; Bastida, Jaume (2012). "Alkaloids from the Hippeastrum genus: chemistry and biological activity". Rev. Latinoamer. Quím. 40 (2): 83–98. Retrieved 2013-12-01.
- Linnaeus, C. Species Plantarum 1, 292-293 1753 Linnaeus' original species of Amaryllis were: A. lutea, A. atamasco, A. formossissima, A. belladonna, A. sarniensis, A. zeylanica, A. longifolia, A. orientalis and A. guttata. All of these were subsequently assigned to as many different genera (Sealy 1938) accessed November 29, 2013
- Natural History Museum: The George Clifford Herbarium accessed November 26, 2013
- Linnaeus, C. Amaryllis. Hortus Cliffortianus, 135 (1737) accessed November 29, 2013
- J. R. Sealy. Amaryllis and Hippeastrum. Bulletin of Miscellaneous Information (Royal Gardens, Kew). Vol. 1939, No. 2 (1939), pp. 49–68 For discussion on status of Leopoldia, see p. 65 accessed November 26, 2013
- Herbert, W. (1819). "Amaryllis reticulata". Curtis's Botanical Magazine 47: 2113. Retrieved 2013-11-27.
- Herbert, William (1821). "An Appendix: Preliminary Treatise (pp. 1-14) and A Treatise &c. (pp. 15-52)". The Botanical Register (Picadilly, London: Printed for James Ridgway and Sherwood, Neely, and Sons) 7. Retrieved 2012-11-26. For references to Hippeastrum, see p. 7ff. and 31-4; for detailed descriptions of Hippeastrum splendens, see pp. 52–3.
- Uphof, J. C. T. 1938. The history of nomenclature - Amaryllis belladonna( Linn.) Herb., and Hippeastrum (Herb.). Herbertia 5: 100-111. accessed November 29, 2013
- Uphof, J. C. T. 1939. Critical review of Sealy's "Amaryllis and Hippeastrum". Herbertia 6: 163-166. accessed November 29, 2013
- Meerow, Alan W.; Van Scheepen, Johan; Dutilh, Julie H.A. (1997), "Transfers from Amaryllis to Hippeastrum (Amaryllidaceae)", Taxon 46 (1): 15–19, doi:10.2307/1224287
- Garbari, F.; Greuter, W. (1970). "On the Taxonomy and Typification of Muscari Miller (Liliaceae) and Allied Genera, and on the Typification of Generic Names". Taxon 19 (3): 329–335. doi:10.2307/1219056.
- How to Make Your Amaryllis Bloom Again, The United States National Arboretum, retrieved 2013-11-26
- "Hippeastrum". Amaryllidaceae.org. Retrieved 2013-11-30.
- Traub, H. P. 1958. The Amaryllis Manual. MacMillian and Co., New York. accessed November 30, 2013
- Traub, H. P. 1980. The Subgenera of the Genus Amaryllis. Plant Life 36: 43-45.
- Vargas C J.C. 1984. The Peruvian Species of the Genus Amaryllis (Amaryllidaceae). Herbertia 40: 112-134.
- Brian Mathew. : Hippeastrum - The secret of the knights star. Kew Magazine Spring 1999, Royal Botanical Gardens Kew accessed November 26, 2013
- Carter, Kathie (2010). "Amaryllis". University of California Cooperative Extension. Retrieved 2013-11-30.
- "Houston Amaryllis Society". Retrieved 2013-11-26.
- Yolanda Wilson. What Do You Say to a Naked Lady? (Amaryllis belladonna). Washington State University Clark County Extension. October 2005 accessed December 19 2013
- Aiton, W. "Hexandra Monogyna : Amaryllis". Hortus Kewensis 1: 417. Retrieved 2013-11-29.
- Curtis, W. (1795). "Amaryllis equestris". Botanical Magazine 9–10: 304. Retrieved 2013-11-29.
- John Sims. Amaryllis reticulata. Curtis's Botanical Magazine. vol. 17-18:657 (1803) accessed November 29, 2013
- von Jacquin, Nikolaus Joseph (1797–1804). Hortus Schoenbrunnensis. Plantarum Rariorum Horti Caesarei Schoenbrunnensis Descriptiones et Icones (4 volumes). Vienna. Retrieved 2013-11-29.
- von Jacquin, Nikolaus Joseph (1797–1804). "Amaryllis equestris (t. 63)". Hortus Schoenbrunnensis. Plantarum Rariorum Horti Caesarei Schoenbrunnensis Descriptiones et Icones. Vienna. Retrieved 2013-11-29.
- Don, M. (4 January 2013). "Their huge flower trumpets are usually associated with the festive season, but plant the bulbs now and you can enjoy amaryllis in spring". Daily Mail. Retrieved 2013-11-29.
- Meerow, Alan W. (2009). "Tilting at windmills: 20 years of Hippeastrum breeding". Israel Journal of Plant Sciences 57 (4): 303–313. doi:10.1560/IJPS.57.4.303.
- Meerow, A. W. 1999. Breeding Amaryllis. Herbertia 54: 67-83.
- Paula Szilard: Getting your Hippeastrum (Amaryllis) to Bloom. Tropical Plant Society accessed December 2, 2013
- "Amarilis - Hippeastrum vittatum". Infojardin. Retrieved 2013-12-02.
- Royal Horticultural Society: Hippeastrum accessed December 2, 2013
- Fellers, J.D. (1998). "Progeny of Hippeastrum papilio". Herbertia 53: 129–144. Retrieved 2013-12-02.
- Williams, M. & T. R. Dudley. 1984. Chromosome Count for Hippeastrum iguazuanum. Taxon, Vol. 33, No. 2, pp. 271–275.
- "Multiplication sexuée" (in French). Amaryllidaceae.org. Retrieved 2013-12-20.
- Williams, M. 1980. Self-sterility in Hippeastrum (Amaryllis) species. Amaryllis Bulletin 1:20.
- "Pests". Hippeastrum.com. Retrieved 2013-12-20.
- Meerow, Alan (1999). "Amaryllis and Alstroemeria: Old Crops, New Potential". Retrieved 2013-12-03.
- Hessayon, D.G. (1999). The Bulb Expert. London: Transworld Publishers.
- Maguire's Hippeastrum Farm
- Pacific Bulb Society: Stagonospora curtisii
- Read, V. 1999. Developments in Hippeastrum hybridization, 1799–1999. Herbertia 54:84-109.
- San Marcos Growers: Hippeastrum x johnsonii - St. Joseph's Lily
- "Hippeastrum (?) x johnsoni". Bulb Society. Retrieved 2013-12-20.
- Ephrath, J.E.; Ben-Asher, J.; Baruchin, F.; Alekperov, C.; Dayan, C.; Silberbush, M. (2001). "Various Cutting Methods For the Propagation of Hippeastrum Bulbs". Biotronics 30: 75–83. Retrieved 2013-12-20.
- STANCATO, G.C. and MAZZAFERA, P. Effects of light on the propagation and growth of bulbs of Hippeastrum hybridum cv. Apple Blossom (Amaryllidaceae). Sci. agric. (Piracicaba, Braz.) 1995, vol. 52, no. 2, pp. 331–334.ISSN 0103-9016. doi: 10.1590/S0103-90161995000200021
- SEABROOK, J. and B. CUMMING. 1977. The in vitro propagation of Amaryllis (Hippeastrum spp. hybrids). In vitro 13(12):831-836.
- Vargas, T.E. C., Maira Oropeza C. & Eva de García. 2006. PROPAGACIÓN in vitro DE Hippeastrum. Agronomía Trop. 56(4): 621-626.
- J. Sultana, N. Sultana, M. N. A. Siddique, A. K. M. A. Islam, M. M. Hossain and T. Hossain. IN VITRO BULB PRODUCTION IN HIPPEASTRUM (HIPPEASTRUM HYBRIDUM). Journal of Central European Agriculture Vol 11 (2010) No 4 (469-474)
- "IUCN Red List". Retrieved 2013-12-20.
- Ockenga, Starr (2002). Amaryllis. New York: Clarkson Potter. ISBN 978-0-609-60881-4.
- "RHS Plant Selector - Hippeastrum 'Bestseller'". Retrieved 22 June 2013.
- RHS: Belinda
- "RHS Plant Selector - Hippeastrum 'Star of Holland'". Retrieved 22 June 2013.
- "Alkaloids from Hippeastrum papilio". Molecules 16: 7097–7104. 2011. doi:10.3390/molecules16087097.
- Youssef DT. Alkaloids of the flowers of Hippeastrum vittatum. J Nat Prod. 2001 Jun;64(6):839-41.
- Flavia Schurmann Da Silva, A.; de Andrade, Jean Paulo; Bevilaqua, Lia R.M.; De Souza, Marcia Maria; Izquierdo, Ivan; Teresinha Henriques, Amélia; Silveira Zuanazzi, José Angelo (2006). "Anxiolytic-, antidepressant- and anticonvulsant-like effects of the alkaloid montanine isolated from Hippeastrum vittatum". Pharmacology, biochemistry and behavior 85 (1): 148–154. Retrieved 2013-12-20.
- SA Mitchell, MH Ahmad. A review of medicinal plant research at the University of the West Indies, Jamaica, 1948–2001. West Indian Med J 2006; 55 (4) pp. 243.
- "Amaryllis Campaign". Huntington Society of Canada. Retrieved 2011-12-11.
- "Amaryllis fundraising store". Huntington's Disease Society of America. Retrieved 2011-12-11.
- "HDA homepage". Huntington's Disease Society (England & Wales). Retrieved 2011-12-11.
- "Amaryllis logo". Huntington's Disease Association Northern Ireland. Retrieved 2011-12-11.
- WCSP (2011). "Search for Hippeastrum". World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Retrieved 2011-11-20.
- Ochoa, C.M. (2006), "Hippeastrum ugentii (Amaryllidaceae: Hippeastreae), a new species from central Peru", Phytologia 88 (2): 176–178, retrieved 2011-11-20
- Manning, R. 1974. Sprekelia-Amaryllis cross. Plant Life, 30:85-86.
- Pacific Bulb Society: xHippeastrelia
- Amaryllideae. Philip Miller. Miller's dictionary of gardening, botany, and agriculture; revised. Oxford University 1834
- Hessayon, D.G. The Bulb Expert. Transworld Publishers Ltd. Londres, 1999.
- Rosella Rossi. 1990. Guía de Bulbos. Grijalbo. Barcelona
- Phillips, R. & Rix, M. 1989. Bulbs. Pan Books Ltd.
- Taylor, P. 1996. Gardening with Bulbs. Pavilion Books Ltd., Londres.
- Hartmann, H. & Kester, D. 1987. Propagación de plantas, principios y prácticas. Compañía Editorial Continental S.A., México. ISBN 968-26-0789-2
- Horace F Clay, James C. Hubbard. Tropical Exotics: Hippeastrum vittatum. University of Hawaii Press, 1987. ISBN 0-8248-1127-5, 9780824811273
- Rina Kamenetsky, Hiroshi Okubo (Eds.) Ornamental Geophytes: From Basic Science to Sustainable Production: Hippeastrum (Amaryllis). CRC Press, 2012. ISBN 1-4398-4924-2, 9781439849248
- James Herbert Veitch. Hortus Veitchii: A History of the Rise and Progress of the Nurseries of Messrs James Veitch and Sons. Cambridge University Press, 2011. ISBN 1-108-03736-4, 9781108037365
- James Cullen, Sabina G. Knees, H. Suzanne Cubey (eds.) The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass. Cambridge University Press, 2011. ISBN 0521761476, 9780521761475
- Michael G. Simpson. Plant Systematics. Academic Press, 2011 ISBN 0-08-051404-9, 9780080514048
- Read, Veronica A. (2004), Hippeastrum : the gardener's amaryllis, Portland OR: Timber Press, ISBN 978-0-88192-639-2
- Arthington Worsley. The Genus Hippeastrum: A Monograph ... Nabu Press 2012. ISBN 978-1-277-39963-9 (originally published 1923)
- Khalid Jamil. Hippeastrum: Technique of Bulb and Flower Production. LAP Lambert Academic Publishing, 2011. ISBN 3-8454-2259-9, 9783845422596
Articles and theses
- W. L. TJADEN. Amaryllis belladonna and the Guernsey lily: an overlooked clue. Journal of the Society for the Bibliography of Natural History, NOVEMBER 1979, Vol. 9, No. 3 : pp. 251–256 (doi: 10.3366/jsbnh.19126.96.36.199)
- Daniela Baltac Rǎdescu. "Cercetări privind caracterele morfologice ale unor soiuri de Hippeastrum vitatum şi comportarea lor în diferite variante tehnologice" (Research on morphological characters of certain varieties of Hippeastrum vitatum and their behavior in different technological options) Ph.D Thesis, Facultatea de HORTICULTURĂ (Faculty of Horticulture), UNIVERSITATEA DE ŞTIINŢE AGRONOMICE ŞI MEDICINĂ VETERINARĂ - BUCUREŞTI. 2012
- Amaryllis/Hippeastrum identification
- Romanian article about Hippeastrum
- Forum for Hippeastrum and Amaryllis
- Hippeastrum Care - Royal Botanic Gardens
- RHS advice for the UK
- Pacific Bulb Society: Hippeastrum
- University of Florida Amaryllis information
- Bulb Society: Images of Hippeastrum cultivars
- Video of Hippeastrum flowering
- A.J. Pertuit. Understanding and Producing Amaryllis Clemson University August 1995
- DE TEELT VAN HIPPEASTRUM (AMARYLLIS}. PROEFSTATION VOOR TUINBOUW ONDER GLAS TE NAALDWIJK. 1980 [The production of Hippeastrum (Amaryllis)]
- Royal Botanical Gardens Kew: Glossary
- Pacific Bulb Society: Images of Hippeastrum species
- Pacific Bulb Society: Images of Hippeastrum hybrids
- Shirley Hibberd: Lecture on the Amaryllis. William Robinson. The Garden: An Illustrated Weekly Journal of Gardening in All Its Branches, Volume 23. 1883 University of Michigan
- James Douglas. THE HIPPEASTRUM. Gardeners' Chronicle, March 24, 1906
|Wikimedia Commons has media related to Hippeastrum.|
|Wikispecies has information related to: Hippeastrum|