The Amaryllidaceae are a family of herbaceous, mainly perennial and bulbous (rarely rhizomatous) flowering plants in the monocot order Asparagales. The family takes its name from the genus Amaryllis and is commonly known as the amaryllis family. The leaves are usually linear, and the flowers are usually bisexual and symmetrical, arranged in umbels on the stem. The petals and sepals are undifferentiated as tepals, which may be fused at the base into a floral tube. Some also display a corona. Allyl sulfide compounds produce the characteristic odour of the onion subfamily (Allioideae).
The family, which was originally created in 1805, now contains about 1600 species, divided into 71 genera, 17 tribes and three subfamilies, the Agapanthoideae (Agapanthus), Allioideae (onions, garlic and chives) and Amaryllidoideae (amaryllis, daffodils, snowdrops). Over time, it has seen much reorganisation and at various times was combined with the related Liliaceae. Since 2009, a very broad view has prevailed based on phylogenetics, and including a number of other former families.
The family is found in tropical to subtropical and temperate areas of the world and includes many ornamental garden plants and vegetables.
Description
The Amaryllidaceae are mainly terrestrial (rarely aquatic) flowering plants that are herbaceous or succulent geophytes (occasionally epiphytes) that are perennial, with the exception of four species. Most genera grow from bulbs, but a few such as Agapanthus, Clivia and Scadoxus develop from rhizomes (underground stems).
The leaves are simple, rather fleshy and two-ranked with parallel veins. Leaf shape may be linear, strap like, oblong, elliptic, lanceolate (lance shaped) or filiform (threadlike). The leaves which are either grouped at the base or arranged alternatively on the stem may be sessile or petiolate and possess a meristem.
The flowers, which are hermaphroditic (bisexual), are actinomorphic (radially symmetrical), rarely zygomorphic, pedicellate or sessile, and are typically arranged in umbels at the apex of leafless flowering stems, or scapes and associated with a filiform (thread-like) bract. The perianth (perigonium) consists of six undifferentiated tepals arranged in two whorls of three. The tepals are similar in shape and size, and may be free from each other or fused at the base (connate) to form a floral tube (hypanthium). In some genera, such as Narcissus, this may be surmounted by cup or trumpet-shaped projection, the corona (paraperigonium or false corolla). This may be reduced to a mere disc in some species.
The position of the ovary varies by subfamily. The subfamilies Agapanthoideae and Allioideae have superior ovaries, while the Amaryllidoideae have inferior ovaries. The six stamens are arranged in two whorls of three, occasionally more as in Gethyllis (Amaryllidoideae, 9–18).
The fruit is dry and capsule-shaped, or fleshy and berry-like.
The Allioideae produce allyl sulfide compounds which give them their characteristic smell.
Taxonomy
History
Pre-Darwinian
Linnaeus described the type genus Amaryllis, from which the family derives its name, in his Species Plantarum in 1753, with nine species, in the Hexandria monogynia (i.e. six stamens and one pistil) containing 51 genera in total in his sexual classification scheme. The name Amaryllis had been applied to a number of plants over the course of history.
Hexandria monogynia has come to be treated as either liliaceous or amaryllidaceaeous (see Taxonomy of Liliaceae) over time. From 1763, when Michel Adanson conceived of these genera as 'Liliaceae' it was included in this family, placing Amaryllis in Section VII, Narcissi of his scheme, in which the Liliaceae had eight sections.
With de Jussieu came the formal establishment of organising genera into families (ordo) in 1789. De Jussieu established the hierarchical system of taxonomy (phylogeny), placing Amaryllis and 15 related genera within a division of monocotyledons, a class (III) of Stamina Perigynia and 'order' Narcisse, divided into three subfamilies. This system also formally described the Liliaceae, which were a separate order within the Stamina perigynia (Lilia). The use of the term Ordo (order) at that time was closer to what we now understand as family, rather than order. In creating his scheme, De Jussieu used a modified form of Linnaeus' sexual classification, but with the respective topography of stamens to carpels rather than just their numbers.
The family Amaryllidaceae was formally named as 'Amaryllidées' (Amaryllideae) in 1805, by Jean Henri Jaume Saint-Hilaire. In 1810 Brown proposed that a subgroup of Liliaceae be distinguished on the basis of the position of their ovaries (inferior) and be referred to as Amaryllideae and in 1813 de Candolle described Liliacées Juss. and Amaryllidées Brown as two quite separate families. The literature on the organisation of genera into families and higher ranks became available in the English language with Samuel Frederick Gray's A natural arrangement of British plants (1821). Gray used a combination of Linnaeus' sexual classification and Jussieu's natural classification to group together a number of families having in common six equal stamens, a single style and a perianth that was simple and petaloid, but did not use formal names for these higher ranks. Within the grouping, he separated families by the characteristics of their fruit and seed. He treated groups of genera with these characteristics as separate families, such as Amaryllideae, Liliaceae, Asphodeleae, and Asparageae.
John Lindley (1830, 1846) was the other important British taxonomist of the early 19th century. In his first taxonomic work, An Introduction to the Natural System of Botany (1830), he partly followed De Jussieu by describing a subclass he called 'Endogenae, or Monocotyledonous Plants' (preserving de Candolle's Endogenæ phanerogamæ) divided into two tribes, the Petaloidea and Glumaceae. He divided the former, often referred to as petaloid monocots, into 32 orders, including the Amaryllideae. He defined the latter as "Hexapetaloideous bulbous hexandrous monocotyledons, with an inferior ovarium, a six-parted perianthium with equitant sepals, and flat, spongy seeds" and included Amaryllis, Phycella, Nerine, Vallota, and Calostemma.
By 1846, in his final scheme Lindley had greatly expanded and refined the treatment of the monocots, introducing both an intermediate ranking (Alliances) and tribes within families. Lindley placed the Liliaceae within the Liliales, but saw it as a paraphyletic ("catch-all") family, being all Liliales not included in the other orders, but hoped that the future would reveal some characteristic that would group them better. This kept the Liliaceae separate from the Amaryllidaceae (Narcissales Alliance). Of these, Liliaceae was divided into eleven tribes (with 133 genera) and Amaryllidaceae into four tribes (with 68 genera), yet both contained many genera that would eventually segregate to each other's contemporary orders (Liliales and Asparagales respectively). The Liliaceae would be reduced to a small 'core' represented by the tribe Tulipeae (18 genera), while large groups such Scilleae and Asparagae would become part of Asparagales either as part of the Amaryllidaceae or as separate families. While of the four tribes of the Amaryllidaceae, the Amaryllideae and Narcisseae would remain as core amaryllids while the Agaveae would be part of Asparagaceae, but the Alstroemeriae would become a family within the Liliales.
Since then, seven of Linnaeus' Hexandria monogynia genera have consistently been placed in a common taxonomic unit of amaryllids, based on the inferior position of the ovaries (whether this be as an order, suborder, family, subfamily, tribe or section). Thus, much of what we now consider Amaryllidaceae remained in Liliaceae because the ovary was superior, till 1926 when John Hutchinson transferred them to Amaryllidaceae. This usage of the family entered the English language literature through the work of Samuel Frederick Gray (1821), William Herbert (1837) and John Lindley (1830, 1846). Meanwhile, Lindley had described two Chilean genera for which he created a new family, Gilliesieae.
The number of known genera within these families continued to grow and, by the time of the Bentham and Hooker classification (1883), the Amaryllidaceae (Amaryllideae) were divided into four tribes, of which only one (Amarylleae) is still included. The Liliaceae were becoming one of the largest families, and Bentham and Hooker divided it into 20 tribes, of which one was the Allieae, which as Allioideae would eventually become part of Amaryllidaceae as two of its three subfamilies. The Allieae included both Agapantheae, the third of the current subfamilies, and Lindley's Gilliesieae as two of its four subtribes. Bentham and Hooker's scheme was the last major classification using the natural approach.
Post-Darwinian Although Charles Darwin's Origin of Species (1859) preceded Bentham and Hooker's publication, the latter project was commenced much earlier and Bentham was initially sceptical of Darwinism. The new phyletic approach changed the way that taxonomists considered plant classification, incorporating evolutionary information into their schemata. The major works in the late 19th and early 20th centuries employing this approach were German, those of Eichler (1875–1886), Engler, Prantl (1886–1924), and Wettstein (1901–1935).
The Amaryllidaceae were treated similarly in the German-language literature to the manner they had been in English. August Eichler (1886) was the first phyletic taxonomist and positioned the Amaryllidaceae and Liliaceae within the Liliiflorae, one of the seven orders of monocotyledons. Liliaceae included both Allium and Ornithogalum (modern Allioideae). Adolf Engler developed Eichler's ideas much further, into much more elaborate schemes that evolved over time, from his 1888 scheme, contributed by Pax to his 1903 version. In the latter, the Liliineae were a suborder of Liliiflorae, including both families Liliaceae and Amaryllidaceae. Within the Liliaceae, the core liliids were segregated in subfamily Lilioideae from the alliaceous subfamily, Allioideae. Allieae, Agapantheae, and Gilliesieae were the three tribes within this subfamily. A somewhat similar approach to Liliiflorae was adopted by Wettstein (without suborders or tribes), and with Alliodeae (Allium) and Lilioideae (Ornithogalum) as subfamilies of Liliaceae. Wettstein's Amaryllidaceae contained three subfamilies, including Amaryllidoideae and Agavoideae.
The early 20th century was marked by increasing doubts about the placement of the alliaceous genera within Liliaceae. Lotsy was the first taxonomist to propose separating them, and in his system he describes Agapanthaceae, Alliaceae, and Gilliesiaceae as new and separate families from Liliaceae. This approach was adopted by a number of other authorities, such as Dahlgren (1985) and Rahn (1998).
Another approach was that of John Hutchinson (1926), who performed the first major recircumscription of the family in over a century. He doubted Brown's dictum that the position of the ovary was the distinguishing feature that separated Amaryllidaceae and Liliaceae. He treated Amaryllidaceae as bulbous plants with umbellate inflorescences, the latter characteristic being the defining feature: "an umbellate inflorescence subtended by an involucre of one or more spathaceous bracts". His work on this has been upheld by subsequent research and his definition remains valid today. Using this criterion, he removed a number of taxa (Agavaceae, Hypoxidaceae, Alstroemeriaceae) and transferred the Agapantheae, Allieae, and Gilliesieae from Liliaceae to Amaryllidaceae.