| Amaryllidoideae | |
|---|---|
| Amaryllis belladonna | |
| Scientific classification | |
| Kingdom: | Plantae |
| clade: | Angiosperms |
| clade: | Monocots |
| Order: | Asparagales |
| Family: | Amaryllidaceae |
| Subfamily: | Amaryllidoideae |
| Genera | |
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see article |
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Amaryllidoideae is the subfamily of flowering plants that takes its name from the genus Amaryllis. It is part of the family Amaryllidaceae, in order Asparagales. The most recent APG classification, APG III, takes a broad view of the Amaryllidaceae, which then has three subfamilies, one of which is Amaryllidoideae (the old Amaryllidaceae family), and the others are Allioideae (the old Alliaceae family) and Agapanthoideae (the old Agapanthaceae family).[1] The subfamily consists of about sixty genera, with over eight hundred species, and a worldwide distribution.[2]
The Amaryllidoideae are herbaceous, perennial flowering plants, usually with bulbs (some are rhizomatous). Their fleshy leaves are arranged in two vertical columns, and their flowers are large.[2]
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Members of Amaryllidoideae are perennial, mostly deciduous, rarely shrubby or treelike plants, often with bulbs or, rarely, with rhizomes, as in the genera Clivia, Cryptostephanus and Scadoxus. While growing, the bulb is kept deep below ground by a special type of root that lengthen and contract. Leaves are arranged in a basal rosette or fan. They are often narrow, with an entire or spiny margin, and without marked olours, in particular they are not onion-scented. Some genera, like Eucrosia and Scadoxus, which occupy habitats with low light-intensity, have leaves that are broad and flattened, whereas in semi-arid regions like southern Africa, species of Brunsvigia, Crossyne, Gethyllis and Haemanthus have leaves covered with variously shaped hairs. The leaves in Crossyne and some Haemanthus species are also attractively spotted with dark green or red.[3][4][5]
The flowers are large and showy, bisexual, trimerous, actinomorphic (less often slightly zygomorphic, as in Sprekelia). Shape of the flowers varies from star-like to trumpet-shaped or tubular and Colours range from red, orange, yellow and pink to white, whereas bluish flowers are only found in Griffinia, Worsleya and Lycoris. The perianth present 6 segments arranged in two whorls, free or fused to form a short tube. The flowers of Narcissus (the popular daffodil) characteristically have a large, cup-shaped corona, which is an outgrowth of the tepals. The androecium is composed by six stamens, inserted at the perianth throat or at the base of each tepal. Some Griffinia species have five stamens and some Gethyllis species have multiple stamens with about 60 anthers. In Pancratium and Hymenocallis the stamens are fused to form a large cup, known as "staminal cup" which resembles the corona in Narcissus. The ovary is inferior (located below the tepals), with three locules and few to many ovules per locule. All the members of the subfamily produce nectar and are often heavily scented. The inflorescence can be of one or many flowers in a terminal spike, raceme, panicle or, more often, in an umbel-like inflorescence, subtended by an involucre of one to many bracts and with ephemeral hyaline bracts between the flowers. The inflorescence appear at the end of a leafless stem, called a scape. In unusual genera like Gethyllis, however, the scape carries only one flower and remains subterranean. [3][4][5]
The fruit is a dry capsule, or more rarely, a fleshy berry and contain dry, dark and often flattened, or fleshy, round, and greenish seeds. The seeds have an oily endosperm and usually with a black or brown phytomelanous testa, sometimes with a caruncular elaiosome at the chalazal end. [3][4][5]
The most common basic chromosome number in the subfamily is x = 11, although during its evolution a vast arrange of different basic chromosome numbers arose, from x= 6 to x= 23. [4]
Members of this subfamily present a unique type of alkaloids, the norbelladine alkaloids, which are tyrosine derivatives (combined with 4-methylcatechol). They are responsible for the poisonous properties of a number of the species. Over 200 different chemical structures of these compounds are known, of which 79 or more are known from Narcissus alone.[6]
Members of the subfamily are widespread, being found in the Holarctic, Paleotropical, Neotropical, Cape, and Australian regions. In the Neotropics, the family occurs from Mexico through Central America and the West Indies to Chile and Argentina in South America. Notable areas of diversity throughout this range include eastern Brazil, north-central Chile (outside of the tropical zone, however), and the central Andes of Ecuador and Peru. Hippeastrum is primarily found in the Andes and eastern Brazil, Hymenocallis occurs mostly in Mesoamerica, Clinanthus is largely endemic to Peru, and Zephyranthes is broadly distributed. The greatest generic diversity is found in Peru.
The group was first described (as the family Amaryllidaceae) by the French naturalist Jean Henri Jaume Saint-Hilaire in 1805. The type genus, Amaryllis, is named after Amaryllis, a beautiful shepherdess mentioned by Theocritus, Virgil and Ovid, and hence an allegory of beauty.
An Amaryllidaceae family has been recognized, with varying definitions, by most classification systems of the 20th Century, although the Cronquist system included it within a very broadly defined Liliaceae. The two families were traditionally separated by including species with inferior ovaries in Amaryllidaceae and those with superior ovaries in Liliaceae.
The APG initially (1998) recognized the Agapanthaceae, Alliaceae, and Amaryllidaceae sensu stricto as separate families. The 2003 revision tentatively combined the three as subtaxa of a single family in the order Asparagales, citing Alliaceae Batsch (1786) as the name of earliest priority. The most recent revision (2009) is clear that all three families should be combined as separate subfamilies of a broadly defined Amaryllidaceae,[1] the approach followed here.
The APG III approach has been disputed. Differences between the subfamilies regarding chemical compounds and morphology are considered sufficiently important by some authors to keep them as three separate families.[4] If the Amaryllidoideae is treated as a family, it is one of the few families of the higher Asparagales well defined by other than molecular characters, namely the combination of umbellate cymes, inferior ovaries, and unique alkaloid chemistry.[7]
Amaryllidoideae and its sister genus Agapanthus (the subfamily Agapanthoideae), originated in western Gondwanaland, and Africa has been the site of considerable innovation in the subfamily's history as well.[8][9] Crinum is unusual in the subfamily because of its dispersal ability that comes from seeds that are adapted for oceanic dispersal and it has a pantropical distribution.[8][9] The most recent data indicate that genetic relationships within the subfamily closely mirror their geographic distributions.[9]
The Calostemmateae, the only exclusively Australasian element of the subfamily, may have been isolated from the African lineages as Australia separated from western Gondwanaland.[8]
The Eurasian/Mediterranean members of the subfamily are the sister group of the American genera, but it is unclear when and how the major dispersal between these areas occurred.[8] There are considerably more species in South America than on the Northern Continent, and there has been some recent movement northward, but this does not imply that the subfamily reached South America earlier.[10][8][9]
The Amaryllidoideae has so far defied precise understanding of its internal phylogeny, and its relationships to other higher Asparagales. Combined analysis of three plastid DNA sequences (rbcL, trnL intron, and trnL-F spacer) for 50 genera of Amaryllidoideae analyzed together with members of Allioideae, Behniaceae, Convallariaceae, Scillioideae, Themidaceae, and Hemerocallidoideae, resolves Agapanthoideae as sister to Amaryllidoideae with weak support and places Agapanthus-Amaryllidoideae as a sister clade to a monophyletic Allioideae.
The African tribe Amaryllideae is sister to the remainder of the Amaryllidoideae. Amaryllis and Boophone forms the most basal branches of the phylogeny inside this tribe. Two major lineages are subsequently resolved in all the analyses. The most diverse of them is the southern African lineage that encompasses Strumaria and its allies. The other is the predominantly sub-Saharan African group that includes Crinum and related genera. [11] The African baccate-fruited Haemantheae and the Australasian Calostemmateae are sister tribes, and the African endemic Cyrtantheae is sister to them both. [12] The most completely resolved and best supported tree for Haemantheae, divides the tribe into two main clades. The smaller clade, uniting Clivia and Cryptostephanus, represents entirely rhizomatous genera that never form bulbs. Cryptostephanus is also the only genus of the tribe that retains the plesiomorphic character of a phytomelanous testa. The second clade contains all of the genera that form true bulbs, though Scadoxus is polymorphic for this character. This second clade contains two subclades that can be characterized morphologically as well. The sister relationship of Haemanthus and Scadoxus is well supported by the morphological synapomorphy of the brush-like inflorescence, facilitated by the reduction in perianth size and the dominance of the spathe bracts during anthesis. The gethyllid subclade is characterized by a suite of morphological characters, such as uniflory, obsolete scape, and the long, aromatic, cylindrical, many-seeded fruit of both recognized genera, in contrast to the one or few seeded berry of the other genera in the tribe.[13]
The Eurasian and neotropical genera of the Amaryllidoideae are a well-supported clade, and are sister groups.[14] Lycorideae are basal in the Eurasian clade and begin a grade that continues with Hannonia, then Pancratium, then Lapiedra. The genera Galanthus, Narcissus, and Sternbergia are resolved as monophyletic with strong support. Leucojum sensu lato is paraphyletic and recognition of Acis for the mostly autumn-flowering Mediterranean species is supported by molecular data.[15]
The American genera of the family form two major clades. The first, or ‘‘hippeastroid’’ clade, are diploid (x = 11), primarily the extra-Andean element of the family (though several of the genera do have Andean representatives), comprising the genera treated as the tribe Hippeastreae. The second clade constitutes the tribes centered in the Andes whose basic chromosome number is derived by polyploidy (x = 23). Several genera within the hippeastroid clade resolve as polyphyletic (such as Rhodophiala and Zephyranthes) and the possibility of reticulate evolution (i.e., early hybridization) in these lineages was hypothesized. A petiolate-leafed Andean subclade, containing elements of both Eucharideae and Stenomesseae, was resolved. Within the Andean subclade, Eustephieae resolves as sister to all other tribes; a distinct petiolate-leafed group is resolved, combining the tribe Eucharideae and the petiolate Stenomesseae (Eucharideae has nomenclatural priority); and a distinct Hymenocallideae is supported. It was inferred from the molecular data that a great deal of the diversity of the family in the Americas is recent, and that the American Amaryllidoideae may have been reduced to peripheral isolates some time after its initial entry and spread through the Americas.[16] In both of the major American clades, there is a small tribe that is sister to the rest of the clade, Eustephieae in the Andean group, and Griffineae in the hippeastroid clade. These two small tribes may represent either ancestral or merely very isolated elements of their respective clades.
A cladogram which summarizes the phylogenetic relationships among tribes and subtribes of Amaryllidoideae is given below.
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Two modern sub-classifications of the Amaryllidoideae are those of Müller-Doblies and Müller-Doblies (1996)[17] and Meerow and Snijman (1998).[18] Müller-Doblies and Müller-Doblies recognized ten tribes and 19 subtribes, many of them with a single genus. Meerow and Snijman recognized 14 tribes, with two subtribes only in one of them, resurrected Eustephieae from Stenomesseae and recognized two new tribes, Calostemmateae and Hymenocallideae. Later on, they recognized four subtribes in Amaryllidae,[11] and three subtribes for Haemantheae, changing the taxonomic rank of Gethyllidinae.[13]
Several members of different genera of Amaryllidoideae hybridize readily, and the resulting hybrids are often sterile but can be propagated asexually. A hybrid name is usually reserved for these horticulturally arising hybrids which is indicated by a multiplication sign "×" placed before the name or epithet, as the case may be. Some nothogenera (a taxonomic rank given to artificial hybrids between species from different genera, from the Greek νόθος (“bastard”) and “genus”) of Amaryllidoideae are:
Haemanthus × clarkei W. Wats., is the product of crossing H. albiflos with H. coccineus, it was raised in the UK by 1891.[51][52] Clivia cyrtanthifora was raised by Charles Raes in Ghent, Belgium in the late 1850s and it was suggested to be a hybrid between Clivia miniata and Clivia nobilis,[53][54] which was confirmed later by means of cytogenetics tools. [55] By means of DNA analysis, it was also confirmed that Lycoris straminea originated from hybridization between Lycoris chinensis and Lycoris radiata, and Lycoris caldwellii and Lycoris albiflora derived from hybridization between L. chinensis and Lycoris sprengeri.[56]
In the genus Narcissus, high frequencies of natural hybrids have been reported and hybridization has been suggested as an explanation for the phenotypic variability within and between populations.[57] Narcissus cavanillesii is a rare species, while N. serotinus is widely distributed across the Mediterranean. The hybrid, N. x perezlarae, is quite frequent in southeastern Spain but is scarce in Portugal.[58]
Most species are adapted to seasonal climates that have a pronounced dry or cold period unfavourable for plant growth and during which the plants remain dormant. As a result most species are deciduous. Evergreen species are restricted to subtropical forests or savannah, temperate grasslands and perennially moist fynbos. The aboveground parts (leaves and stems) of deciduous species die down when the bulb or corm enters dormancy. The plants thus survive periods that are unfavourable for growth by retreating underground. This is particularly useful in grasslands and fynbos, which are adapted to regular burning in the dry season. At that point the plants are dormant and their bulbs or corms are able to survive underground. The Neotropical genera of Amaryllidoideae are chiefly adapted for seasonally dry habitats and some prefer truly xeric environments in which their bulbs may remain dormant for a period longer than they are in active growth (e.g., Leptochiton, Paramongaia, some Eucrosia). At the other extreme, species have colonized the understory of rain forests (Eucharis, Griffinia) and aquatic habitats (a number of Hymenocallis, Hippeastrum angustifolium, Crinum). The subfamily has also adapted to the high montane tropical climates of the Andes. Certain genera are primarily found at elevations in excess of 2000 meters; and Clinanthus humilis is found above 4000 meters. This species has adapted to high elevations by retaining the scape (and developing fruit) inside the bulb until the seeds are ripe. [59][60]
Veld fires clear the soil surface of competing vegetation and fertilise it with ash. With the arrival of the first rains, the dormant bulbs are ready to burst into growth, sending up flowers and stems before they can be shaded out by other vegetation. Many Amaryllidoideae species are adapted to cope with wildfires in their natural habitats, and those that depend on fire to flower are appropriately known as "fire lilies". In South Africa, several members of the genus Cyrtanthus are noted for their extremely rapid flowering response to natural bush fires. Indeed, species like Cyrtanthus contractus, widespread in the eastern half of South Africa, as well as Cyrtanthus ventricosus from the south western Cape, and Cyrtanthus odorus from the southern Cape, only flower after fires. The flowers of C. ventricosus are known to reach full flowering stage in just nine days following a fire.[61] At least in C. ventricosus, this dependency on fire for initiating the flowering process is regulated by the smoke. [62] Aspects of the life history of Haemanthus pubescens were examined in the fire-prone Mediterranean climate zone of Lowland Coastal Fynbos in South Africa. The juvenile period of the species spans 9 years. The young reproductive period starts at 10 to 13 years and the reproductive maturity peaked at 16 years. Plants older than 17 years showed a marked reduction in reproductive potential. These age states indicated that the life-history strategy in terms of age states was similar to that of other fynbos plants and showed remarkable synchronization with the suggested fire frequency of about 15 to 20 years for this area. The phenological study indicated that the species is well adapted to the putative fire season. Flowers are only produced toward the end of the fire season, and leaves appear only in the cooler, wetter months when fires are unlikely to occur. Seeds are not dormant and germinate on the soil surface at the start of the cool, wet season.[63]
Members of Amaryllidoideae possess extraordinary diversity in reproductive traits, even among closely related species. The floral diversification that has accompanied the coevolution of flowers and animal pollinators is particularly striking.[64][65]
Heterostyly is a genetically controlled floral polymorphism; distyly and tristyly are characterized by two or three morphs, respectively, that differ in the style length of the carpel and the filament length of the stamen. Pollen grain size and production, and the size of the stigmatic papillae and the corolla also vary. The positions of the stigma and anthers in the different morphs are such that pollinators contact same-level but different floral organs with the same region of their body. Thus pollination occurs and seeds are produced only in intermorph crosses. This is reciprocal herkogamy, a self-incompatibility system. A physiological incompatibility system is also present in distylous species that contributes to an efficient mechanism that avoids selfing and maximizes male and female fitness.[66]
Narcissus, a small genus of animal-pollinated species, has four major classes of stylar condition: stylar monomorphism, stigma-height dimorphism, distyly, and tristyly are represented among the 10 sections recognized in the genus. No other heterostylous taxon displays this range of stylar variation. Monomorphism is the ancestral condition in Narcissus and stigma-height dimorphism appears to have evolved multiple times. Floral morphology and pollinator relationships played an important role in the evolution of stylar polymorphisms in the genus. Long, narrow floral tubes (correlated with relatively precise depth-probed pollination by Lepidoptera) probably promoted the evolution of stigma-height dimorphism. Finally, the unusual conjunction of long, narrow floral tubes and deep coronas, part of a suite of floral features associated with pollination by long-tongued solitary bees, likely facilitated the convergent origins of heterostyly in Narcissus.[67]
Zephyranthes is a rather versatile genus and contains self-incompatible and self-compatible species coupled with positional barrier between stigma and anthers. Furthermore, the genus also contains sexual and agamospermous species. The latter are often self-pollinated and pseudogamous. Zephyranthes atamasco is capable of producing seeds both by self-pollination and by outcrossing with other individuals of the species. Because the styles project beyond the anthers, however, self pollination in nature is probably less frequent than outcrossing.[68] In contrast, it was documented a process of asexual seed production (apomixis) in Zephyranthes texensis.[69] Zephyranthes sulphurea (2n=48) when pollinated with Z. candida (2n=40 and 41) has consistently given rise to seedlings with maternal chromosome number and morphology. On the other hand, the crosses involving sexual species like Z. candida (2n=41) as the female parent have generated a large heterogeneous progeny ranging in chromosome number from 2n=33 to 48 depending upon the number in the male parent. Such versatility of the breeding system together with chromosomal repatterning, hybridization, polyploidy and vegetative multiplication/apomixis explains the origin and preservation of an astonishing range in chromosome numbers from 2n=18 to 96 in this genus.[70]
Especially in Cyrtanthus the flowers are so diverse that they attract sunbirds, bees, long-tongued flies, butterflies and moths. Members of the genus Brunsvigia appear to show considerable variation in pollination syndromes.[71] A total of 22 species of southern African genera Crinum, Cyrtanthus and Pancratium conform to the syndrome of "sphingophily", attracting Sphingidae moths, which includes a long-tubed, pale-coloured perianth that expands more fully at night, a strong sweet fragrance dominated by the acyclic terpenoid alcohol, linalool and abundant nectar.[72] Southern Africa also has several Amaryllidoideae with remarkable dispersal abilities. Species of Brunsvigia, Boophone and Crossyne in particular have large, light, spherical fruiting heads that tumble along the ground in the wind, shedding their seeds as they move.
Worldwide the Amaryllidoideae have greatest economic value as ornamentals. In addition, huge numbers of plants are traded for traditional medicines. Africans use the bulbs and leaves as poultices and decoctions for treating sores and digestive disorders, but in large dosages they are extremely poisonous. The Zulu people of South Africa also use rhizomes of clivias as protective charms. In Peru, the Inca people frequently depicted flowers of Amaryllidaceae (Ismene, Pyolirion and Stenomesson) on ceremonial drinking vessels. In southern Africa, however, indigenous art portraying plants is rare. The single known rock painting of a Brunsvigia species in Lesotho probably emphasizes how much the San people valued the bulbs for their psychoactive effects. [4]
In cool temperate climates, Narcissus (daffodils), Leucojum (snowflakes) and Galanthus (snowdrops) are among the most important spring-flowering bulbs in commerce. Elsewhere, in warm temperate and subtropical climates, species of Amaryllis, Clivia, Hippeastrum, Nerine, and Zephyranthes are the most popular choices for gardens and containers.[4]
Habitat loss is currently the greatest threat to the Amaryllidoideae in South Africa, where 59 species are endangered or vulnerable and 58 species are near threatened.[4]