Hippeastrum

and stamens 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 (borne directly from the stem or peduncle), 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 zygomorphic 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. == Etymology ==

The name Hippeastrum was first given to the genus by Herbert, being derived from the Ancient Greek, Common name 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". ==Taxonomy==

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. for example as Muscari subg. Leopoldia.) Intergeneric hybrids 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 (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. Subgenera A number of subgenera have been proposed over the years. For instance in the 1870s and 1880s John Gilbert Baker considerably reorganised Hippeastrum. In 1878 he described nine sections of the genus, but by 1888 he included seven subgenera, namely (number of species in parentheses) Habranthus (10), Phycella (3), Rhodophiala (5), Macropododastrum (1), Omphalissa (6), Aschamia (10) and Lais (3), some of which have since been treated as separate genera (Habranthus, Rhodophiala). 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), which he included as separate sections of Hippeastrum. In addition, he included many new species being discovered in South America, particularly Chile. His 1878 classification included 47 species, reduced to 38 by 1888. These subgenera were not widely used due to indistinct boundaries of some of the divisions. For reference, these were: • Aschamia (Salisb.) Baker (e.g. H. reginae, H. andreanum, H. scopulorum, H. mandonii, H. leopoldii, H. reticulatum, H. stylosum) • Cephaleon Traub (e.g. H. machupijchense) • Lais (Salisb.) Baker (e.g. H. striatum, H. vittatum, H. breviflorum) • Macropodastrum Baker (e.g. H. elegans) • Omphalissa (Salisb.) Baker (e.g. H. aulicum, H. psittacinum, H. calyptratum, H. cybister, H. pardinum, H. miniatum, H. iguazuanum) • Sealyana Traub (e.g.: H. reticulatum) Following a major recircumscription of Hippeastreae, Hippeastrum was once again formally divided into two subgenera, by the inclusion of the three species of Tocantina: • Hippeastrum subg. Tocantinia (Ravenna) Nic.García (3) • Hippeastrum subg. Hippeastrum (autonym) (~100) Selected species , Plants of the World Online accepts 116 species. Garcia et al. (2019) estimate approximately 100 species in subgenus Hippeastrum, together with 3 in subgenus Tocantinia. • Hippeastrum angustifolium Pax • Hippeastrum arboricola (Ravenna) Meerow • Hippeastrum aulicum (Ker Gawl.) Herb. • Hippeastrum aviflorum (Ravenna) Dutilh • Hippeastrum calyptratum (Ker Gawl.) Herb. • Hippeastrum canterai Arechav. • Hippeastrum correiense (Bury) Worsley • Hippeastrum cybister (Herb.) Benth. ex Baker • Hippeastrum evansiae (Traub & I.S.Nelson) H.E.Moore • Hippeastrum ferreyrae (Traub) Gereau & Brako • Hippeastrum iguazuanum (Ravenna) T.R.Dudley & M.Williams • Hippeastrum leopoldii T.Moore • Hippeastrum miniatum (Ruiz & Pav.) Herb. • Hippeastrum papilio (Ravenna) Van Scheepen • Hippeastrum pardinum (Hook.f.) Dombrain • Hippeastrum petiolatum Pax • Hippeastrum psittacinum (Ker Gawl.) Herb. • Hippeastrum puniceum (Lam.) Voss. Syn. H. equestre (Aiton) • Hippeastrum reginae (L.) Herb. • Hippeastrum striatum (Lam.) H.E.Moore syn. H. rutilum (Ker Gawl.) Herb. • Hippeastrum reticulatum (L'Hér.) Herb. syn. H. striatifolium (Sims) • Hippeastrum vittatum (L'Hér.) Herb. Unplaced names include Hippeastrum ugentii, considered in the Kew World Checklist of Selected Plant Families as probably a Crinum. Hybrids include Hippeastrum ×johnsonii. == 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. == Ecology ==

Reproduction Species are generally diploid with 2n=22 chromosomes, but some species, such as Hippeastrum iguazuanum, have 24. The genus has a degree of interspecies intercompatibility allowing crossing. 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 hummingbirds in subtropical areas, and moths. Pests 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). The leaves are also eaten by grasshoppers, and grasshoppers commonly plant egg pods in the ground near Hippeastrum bulbs, which erupt in the spring, covering the plant with nymphs. Conservation The following species were considered threatened or vulnerable by degradation of their natural habitat, according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species in 1997. • Hippeastrum arboricolum (Argentina) • Hippeastrum aviflorum (Argentina) • Hippeastrum canterai (Uruguay) • Hippeastrum ferreyrae (Peru) • Hippeastrum petiolatum (Argentina & Brazil) == Cultivation ==

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 cultivar 'Clown' (Double Galaxy Group) (white with red stripes) has received the Royal Horticultural Society's Award of Garden Merit. Gallery == Uses ==

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. 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. == Symbolism ==

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. == See also ==