出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/09/07 05:09:05」(JST)
スノードロップ (snowdrop, snow drop)
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| Snowdrop | |
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| Galanthus nivalis common snowdrop |
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| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Asparagales |
| Family: | Amaryllidaceae |
| Subfamily: | Amaryllidoideae |
| Tribe: | Galantheae |
| Genus: | Galanthus L. |
| Type species | |
| Galanthus nivalis L. |
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| Synonyms[1] | |
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Galanthus (snowdrop; Greek gála "milk", ánthos "flower") is a small genus of about 20 species of bulbous perennial herbaceous plants in the family Amaryllidaceae. The plants have two linear leaves and a single small white drooping bell shaped flower with six petal-like (petaloid) tepals in two circles (whorls). The smaller inner petals have green markings.
Snowdrops have been known since the earliest times under various names but were named Galanthus in 1753. As the number of recognised species increased various attempts were made to divide the species into subgroups, usually on the basis of the pattern of the emerging leaves (vernation). In the era of molecular phylogenetics this characteristic has been shown to be unreliable and now seven moleculary defined clades are recognised corresponding to the biogeographical distribution of species. New species continue to be discovered.
Most species flower in winter, before the vernal equinox (20 or 21 March in the Northern Hemisphere), but some flower in early spring and late autumn. Snowdrops are sometimes confused with the two related genera within the tribe Galantheae, snowflakes Leucojum and Acis.
All species of Galanthus are perennial petaloid herbaceous bulbous (growing from bulbs) monocot plants. The genus is characterised by the presence of two leaves, pendulous white flowers with six free perianth segments in two whorls. The inner whorl is smaller than the outer whorl and has green markings.[2]
These are basal, emerging from the bulb initially enclosed in a tubular membranous sheath of cataphylls. These are generally two (sometimes three) and linear, strap-shaped or oblanceolate. Vernation, the arrangement of the emerging leaves relative to each other, varies between species. These may be applanate (flat), supervolute (conduplicate) or explicative (pleated). In applanate vernation the two leaf blades are pressed flat to each other within the bud and as they emerge; explicative leaves are also pressed flat against each other, but the edges of the leaves are folded back (externally recurved) or sometimes rolled; in supervolute plants one leaf is tightly clasped around the other within the bud and generally remains at the point where the leaves emerge from the soil[3] (for illustration, see Stearn[4] and Davis[5]). In the past, this feature has been used to distinguish between species and to determine the parentage of hybrids but has been shown to be homoplasious, and not useful in this regard.
The scape (flowering stalk) is erect, leafless, terete or compressed.[6]
The scape bears at the top a pair of bract-like spathe valves usually fused down one side and joined by a papery membrane, appearing monophyllous (single). From between them emerges a solitary (rarely two), pendulous, nodding, bell-shaped white flower, held on a slender pedicel. The flower bears six free perianth segments (tepals) rather than petals, arranged in two whorls of three, the outer whorl being larger and more convex than the inner series. The outer tepals are acute to more or less obtuse, spathulate or oblanceolate to narrowly obovate or linear, shortly clawed and erect spreading. The inner tepals are much shorter (half to two thirds as long), oblong, spathulate or oblanceolate, somewhat unguiculate (claw like) and tapered to the base and erect. These tepals also bear green markings at the base, apex or both that when at the apex are bridge-shaped over the small sinus (notch) at the tip of each tepal, which are emarginate. Occasionally the markings are either green-yellow, yellow or absent, and the shape and size varies by species.[7][6]
The six stamens are inserted at the base of the perianth, and are very short (shorter than the inner perianth segments), the anthers basifixed (attached at their base) with filaments much shorter than the anthers and dehisce (open) by terminal pores or short slits.[6]
The inferior ovary is three-celled. The style is slender and longer than the anthers, the stigma are minutely capitate. The ovary ripens into a three-celled capsule fruit. This fruit is fleshy, ellipsoid or almost spherical opening by three flaps with seeds that are light brown to white and oblong with a small appendage or tail (elaiosome) containing substances attractive to ants, which distribute the seeds.[6][8]
The chromosome number is 2n=24.[9][7]
Floral formula:
The genus Galanthus is native to Europe and the Middle East, from the Spanish and French Pyrenees in the west through to the Caucasus and Iran in the east, and south to Sicily, the Peloponnese and the Aegean, Turkey, Lebanon and Syria. The northern limit is uncertain because G. nivalis has been widely introduced and cultivated throughout Europe.[2] G. nivalis and some other species valued as ornamentals have become widely naturalized in Europe, North America and other regions.[1]
G. nivalis is the best-known and most widespread representative of the genus Galanthus. It is native to a large area of Europe, stretching from the Pyrenees in the west, through France and Germany to Poland in the north, Italy, northern Greece, Bulgaria, Romania, Ukraine, and European Turkey. It has been introduced and is widely naturalised elsewhere.[10] Although it is often thought of as a British native wild flower, or to have been brought to the British Isles by the Romans, it was probably introduced around the early 16th century and is currently not a protected species in the UK.[11] It was first recorded as naturalised in the UK in Worcestershire and Gloucestershire in 1770.[12] Most other Galanthus species are from the eastern Mediterranean, but several are found in southern Russia, Georgia, Armenia, and Azerbaijan.[13] Galanthus fosteri comes from Jordan, Lebanon, Syria, Turkey, and maybe Israel.[14]
Galanthus grows best in woodland, in acid or alkaline soil,[6] though some are grassland or mountain species.
Snowdrops have been known since early times, being described by the classical Greek author Theophrastus in the fourth century BC in his Περὶ φυτῶν ἱστορία (Latin: Historia plantarum, Enquiry into plants). He gave it, and similar plants, the name λευκόἲον (λευκος, leukos "white" and ἰόν, ion "violet") from which the later name Leucojum was derived. He described the plant as "ἑπεἰ τοῖς γε χρώμασι λευκἂ καἱ οὐ λεπυριώδη" (in colour white and bulbs without scales)[15] and of their habits "Ἰῶν δ' ἁνθῶν τὀ μἑν πρῶτον ἑκφαἱνεται τὁ λευκόἲον, ὅπου μἑν ό ἀἠρ μαλακώτερος εὐθὑς τοῦ χειμῶνος, ὅπου δἐ σκληρότερος ὕστερον, ἑνιαχοῡ τοῡ ἣρος" (Of the flowers, the first to appear is the white violet. Where the climate is mild, it appears with the first sign of winter, but in more severe climes, later in spring)[16]
Rembert Dodoens, a Flemish botanist, had described and illustrated ths plant in 1583 as did Gerard in England in 1597 (probably using much of Dodoens' material), calling it Leucojum bulbosum praecox (Timely bulbous violet). Gerard refers to Theophrastus' description as Viola alba or Viola bulbosa using Pliny's translation, and comments that the plant had originated in Italy and had "taken possession" in England "many years past".[17] The genus was formally named Galanthus and described by Carl Linnaeus in 1753,[18] with the single species, Galanthus nivalis, which is the type species. Consequently, Linnaeus is granted the botanical authority. In doing so, he distinguished this genus and species from Leucojum (Leucojum bulbosum trifolium minus), a name by which it had been previously known.[1][19][20]
In 1763 Adanson began a system of arranging genera in families. Using the synonym Acrocorion (also spelt Akrokorion),[21] he placed Galanthus in the Liliaceae family, section Narcissi.[22] Lamarck provided a description of the genus in his encyclopedia (1786)[23] and later Illustrations des genres (1793).[24] In 1789 de Jussieu, who is credited with the modern concept of genera organised in families, placed Galanthus and related genera within a division of Monocotyledons, using a modified form of Linnaeus' sexual classification but with the respective topography of stamens to carpels rather than just their numbers. In doing so he restored the name Galanthus and retained their placement under Narcissi, this time as a family (known as Ordo, at that time) and referred to the French vernacular name, Perce-neige[25] (Snow-pierce), based on the plants tendency to push through early spring snow (see Ecology for illustration)].[26] The modern family of Amaryllidaceae, in which Galanthus is placed, dates to Jaume Saint-Hilaire (1805) who replaced Jussieu's Narcissi with Amaryllidées.[27] In 1810 Brown proposed that a subgroup of Liliaceae be distinguished on the basis of the position of the ovaries and be referred to as Amaryllideae[28] and in 1813 de Candolle separated them by describing Liliacées Juss. and Amaryllidées Brown as two quite separate families.[29] However, in his comprehensive survey of the Flora of France (Flore française, 1805–1815) he divided Liliaceae into a series of Ordres, and placed Galanthus into the Narcissi Ordre.[30] This relationship of Galanthus to either liliaceous or amaryllidaceaous taxa (see Taxonomy of Liliaceae) was to last for another two centuries till the two were formally divided at the end of the twentieth century.[31] Lindley (1830) followed this general pattern, placing Galanthus and related genera such as Amaryllis and Narcissus in his Amaryllideae (which he called The Narcissus Tribe in English).[32] By 1853, the number of known plants was increasing considerably and he revised his schema in his last work, placing Galanthus together the other two genera in the modern Galantheae in tribe Amarylleae, order Amaryllidaceae, alliance Narcissales.[33] These three genera have been treated together taxonomically by most authors, on the basis of an inferior ovary. As the number of plants increased, so did the taxonomic complexity. By the time Bentham and Hooker published their Genera plantarum (1862–1883)[34] ordo Amaryllideae[35] contained five tribes, and tribe Amarylleae[36] 3 subtribes (see Bentham & Hooker system). They placed Galanthus in subtribe Genuinae and included three species.[37]
| Cladogram of evolutionary lines in Galanthus sensu Ronsted et al.[2] | |||||||||||||||
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Galanthus is one of three closely related genera making up the tribe Galantheae within subfamily Amaryllidoideae (family Amaryllidaceae). Snowdrops are sometimes confused with the other two genera, snowflakes (Leucojum) and Acis. Leucojum species are much larger and flower in spring (or early summer, depending on the species), with all six tepals in the flower being the same size, though some "poculiform" (goblet- or cup-shaped) Galanthus species can have inner segments similar in shape and length to the outer ones. Galantheae are likely to have arisen in the Caucusus.[38]
Galanthus has about 20 species, but new species continue to be described.[1] G. trojanus was identified in Turkey in 2001.[39][40] G. panjutinii (Panjutin's snowdrop)[41] was discovered in 2012 in five locations in a small area (estimated at 20 km2) of the northern Colchis area (western Transcaucasus) of Georgia and Russia.[42][43] G. samothracicus was identified in Greece in 2014. Since it has not been subjected to genetic sequencing, it remains unplaced. It resembles G. nivalis, but is outside that species' distribution.[44][45]
However, many species are difficult to identify and traditional infrageneric classification based on morphological alone, such as those of Stern (1956),[46] Traub (1963)[47] and Davis[48] (1999, 2001),[49][50][6] has not reflected what is known about its evolutionary history due to the morphological similarities among the species, and relative lack of easily discernible distinguishing characteristics.[51][52][53] Stern divided the genus into 3 series according to leaf vernation (the way the leaves are folded in the bud, when viewed in transverse section, see Description);[46]
Stern further utilised characteristics such as the markings of the inner segments, length of the pedicels in relation to the spathe, and the colour and shape of the leaves in identifying and classifying species.
Traub considered them as subgenera;
By contrast Davis, with much more information and specimens, included biogeography in addition to vernation, forming two series. He used somewhat different terminology for vernation, namely applanate (flat), explicative (plicate), and supervolute (convolute). He merged Nivalis and Plicati into series Galanthus, and divided Latifolii into two subseries, Glaucaefolii (Kem.-Nath) A.P.Davis and Viridifolii (Kem.-Nath) A.P.Davis.[49]
Early molecular phylogenetic studies confirmed the genus was monophyletic and suggested four clades, which were labelled as series, and showed that Davis' subseries were not monophyletic.[52][53] An expanded study in 2013 demonstrated seven major clades corresponding to biogeographical distribution. This study used nuclear encoded nrITS (Nuclear ribosomal internal transcribed spacer), and plastid encoded matK (Maturase K), trnL-F, ndhF, and psbK–psbI, and examined all species recognised at the time, and also two naturally occurring putative hybrids. The morphological characteristic of vernation that earlier authors had mainly relied on was shown to be highly homoplasious. A number of species, such as G. nivalis and G. elwesii demonstrated intraspecific biogeographical clades, indicating problems with speciation and there may be a need for recircumscription. These clades were assiged names, partly according to Davis' previous groupings. In this model clade Platyphyllus is sister to the rest of the genus.[2]
By contrast another study performed at the same time, using both nuclear and chloroplast DNA but limited to the 14 species found in Turkey, largely confirmed Davis' series and subseries, and with biogeographical correlation. Series Galanthus in this study corresponded to clade nivalis, subseries Glaucaefolii with clade Elwesii and subseries Viridifolii with clades Woronowii and Alpinus. However, the model did not provide complete resolution.[54]
| Cladogram of evolutionary lines in Galanthus sensu Ronsted et al.[2] | |||||||||||||||||||||||||||||||||||||||
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sensu Ronsted et al. 2013[2]
| Cladogram of evolutionary lines in Galanthus sensu Margoz et al.[54] | |||||||||||||||
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Galanthus is derived from the Greek γάλα (gala), meaning "milk" and ἄνθος (anthos) meaning "flower", alluding to the colour of the flowers. The epithet nivalis is derived from the Latin, meaning "of the snow".[56][57] The word "Snowdrop" may be derived from the German Schneetropfen (Snow-drop), the tear drop shaped pearl earrings popular in the sixteenth and seventeenth centuries. Other, earlier, common names include Candlemas bells, Fair maids of February and White ladies (see Symbols).[20]
Snowdrops are hardy herbaceous plants that perennate by underground bulbs. They are among the earliest spring bulbs to bloom, although a few forms of G. nivalis are autumn flowering.[8][58] In colder climates, they will emerge through snow (see illustration). They naturalise relatively easily forming large drifts. These are often sterile,[59] found near human habitation, and also former monastic sites.[58] The leaves die back a few weeks after the flowers have faded. Galanthus plants are relatively vigorous and may spread rapidly by forming bulb offsets. They also spread by dispersal of seed, animals disturbing bulbs, and water if disturbed by floods.[58][20]
Some snowdrop species are threatened in their wild habitats, due to habitat destruction, illegal collecting and climate change.[2] In most countries collecting bulbs from the wild is now illegal. Under CITES regulations, international trade in any quantity of Galanthus, whether bulbs, live plants, or even dead ones, is illegal without a CITES permit.[60] This applies to hybrids and named cultivars, as well as species. CITES lists all species but allows a limited trade in wild-collected bulbs of just three species (G. nivalis, G. elwesii, and G. woronowii) from Turkey and Georgia (see Horticulture).[61][62] A number of species are on the IUCN Red List of threatened species, with the conservation status being G. trojanus as critically endangered,[63] four species vulnerable, G. nivalis is near threatened[64] and several species show decreasing populations.[2] G. panjutinii is considered endangered. One of its five known sites, at Sochi, was destroyed by preparations for the 2014 Winter Olympics.[42]
Celebrated as a sign of spring, snowdrops can form impressive carpets of white in areas where they are native or have been naturalised. These displays may attract large numbers of sightseers.[58] There are a number of snowdrop gardens in England, Wales, Scotland and Ireland.[65] Several gardens open specially in February for visitors to admire the flowers. Sixty gardens took part in Scotland's first Snowdrop Festival (1 Feb–11 March 2007).[66] Several gardens in England open during snowdrop season for the National Gardens Scheme (NGS) and in Scotland for Scotland's Gardens. Colesbourne Park in Gloucestershire is one of the best known of the English snowdrop gardens, being the home of Henry John Elwes, a collector of Galanthus specimens, and after whom Galanthus elwesii is named.[67][68]
Numerous single- and double-flowered cultivars of Galanthus nivalis are known, and also of several other Galanthus species, particularly G. plicatus and G. elwesii. Also, many hybrids between these and other species exist (more than 500 cultivars are described in Bishop, Davis, and Grimshaw's book, plus lists of many cultivars that have now been lost, and others not seen by the authors). They differ particularly in the size, shape, and markings of the flower, the period of flowering, and other characteristics, mainly of interest to the keen (even fanatical) snowdrop collectors, known as "galanthophiles", who hold meetings where the scarcer cultivars change hands.[69] Double-flowered cultivars and forms, such as the extremely common Galanthus nivalis f. pleniflorus 'Flore Pleno', may be less attractive to some people, but they can have greater visual impact in a garden setting. Many hybrids have also occurred in cultivation.[6]
These species:
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and these cultivars:
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have gained the Royal Horticultural Society's Award of Garden Merit. A list of Irish cultivars can be found here [1]
Propagation is by offset bulbs, either by careful division of clumps in full growth ("in the green"), or removed when the plants are dormant, immediately after the leaves have withered; or by seeds sown either when ripe, or in spring. Professional growers and keen amateurs also use such methods as "twin-scaling" to increase the stock of choice cultivars quickly.
Snowdrops contain also an active lectin or agglutinin named GNA for Galanthus nivalis agglutinin.[79]
In 1995, Árpád Pusztai genetically modified potatoes with the GNA gene, which he discussed on a radio interview in 1998[80] and published in the Lancet in 1999.[81] In 1998, he said in an interview on a World in Action programme that his group had observed damage to the intestines and immune systems of rats fed the genetically modified potatoes. He also said, "If I had the choice I would certainly not eat it", and that "I find it's very unfair to use our fellow citizens as guinea pigs."[80] These remarks started the so-called Pusztai affair.
Galanthus species and cultivars are extremely popular as symbols of spring and are traded more than any other wild-source ornamental bulb genus. Millions of bulbs are exported annually from Turkey and Georgia.[2] For instance export quotas for 2016 for G. elwesii are 7 million for Turkey and 15 million for Georgia. Data for G. worononowii are 15 million for Georgia. These figures include both wild-taken and artificially propagated bulbs.[61]
Andreas Plaitakis and Roger Duvoisin in 1983 suggested that the mysterious magical herb moly that appears in Homer's Odyssey is actually snowdrop. An active substance in snowdrop is called galantamine, which, as an acetylcholinesterase inhibitor, could have acted as an antidote to Circe's poisons.[82] Galantamine (or galanthamine) can be helpful in the treatment of Alzheimer's disease, though it is not a cure;[83] the substance also occurs naturally in daffodils and other narcissi.[84]
low, northern wind; fall snow;
And thou—my loved and dear,
See, in this waste of burthened cloud
How Spring is near!
Walter de la Mare (1950)[85]
Snowdrops figure prominently in art and literature,[86] often as a symbol of spring, purity and religion in poetry (see Symbols), such as Walter de la Mare's poem The Snowdrop (1929).[87] In this poem, he likened the triple tepals in each whorl ("A triplet of green-pencilled snow") to the Holy Trinity.[58] He used snowdrop imagery several times in his poetry, such as Blow, Northern Wind (1950) - see Box.[85]
Early names refer to the association with the religious feast of Candlemas (February 2) the optimum flowering time in which white-robed young women proceeded in the procession associated with the Purification, an alternative name for the feast day. The French name of Violette de la Chandaleur refers to Candlemas, while an Italian name, Fiore della purificazone, refers to purification. The German name of Schneeglöckchen (Little snow bells) also invokes the symbol of bells.[20][58]
| Wikimedia Commons has media related to Galanthus. |
| Wikimedia Commons has media related to Snowdrops in art. |
| Wikispecies has information related to: Galanthus |
| Look up Galanthus in Wiktionary, the free dictionary. |
| Look up snowdrop in Wiktionary, the free dictionary. |
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| リンク元 | 「Galanthus」「スノードロップ」「Galanthus nivalis」 |