Angraecum

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Angraecum
Angraecum sesquipedale - Diogo Correia.jpg
Angraecum sesquipedale habitus
Note extremely long spurs of flowers
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Tribe: Vandeae
Subtribe: Angraecinae
Genus: Angraecum
Bory, 1804 [1]
Type species
Angraecum eburneum
Bory
Species

See list of Angraecum species for complete list

Synonyms [1]
List
    • AerobionKaempf. ex Spreng.
    • AngorkisThouars
    • Angraecoides(Cordem.) Szlach., Mytnik & Grochocka
    • Arachnangraecum(Schltr.) Szlach., Mytnik & Grochocka
    • BonnieraCordem.
    • Boryangraecum(Schltr.) Szlach., Mytnik & Grochocka
    • ConchograecumSzlach., Grochocka, Oledrz. & Mytnik
    • CtenorchisK.Schum.
    • Dolabrifolia(Pfitzer) Szlach. & Romowicz
    • EichlerangraecumSzlach., Mytnik & Grochocka
    • Gomphocentrum(Benth.) Szlach., Mytnik & Grochocka
    • Hadrangis(Schltr.) Szlach., Mytnik & Grochocka
    • HermansiaSzlach., Mytnik & Grochocka
    • Humblotiangraecum(Schltr.) Szlach., Mytnik & Grochocka
    • Lemurangis(Garay) Szlach., Mytnik & Grochocka
    • LepervencheaCordem.
    • LesliegraecumSzlach., Mytnik & Grochocka
    • MacroplectrumPfitzer
    • MonixusFinet
    • Pectinaria(Benth.) Cordem.
    • PectinariellaSzlach., Mytnik & Grochocka
    • Perrierangraecum(Schltr.) Szlach., Mytnik & Grochocka
    • Pseudojumellea(Schltr.) Szlach., Mytnik & Grochocka
    • RudolfangraecumSzlach., Mytnik & Grochocka

Angraecum, also known as comet orchid, [2] [3] [4] is a genus of the family Orchidaceae native to tropical and South Africa, as well as Sri Lanka. It contains 223 species. [1]

Contents

Etymology

Despite the genus's distribution being largely confined to Africa and its offshore islands, the genus name is a latinization of the Indonesian and Malay word anggrek ("orchid"), itself ultimately from Javanese ꦲꦔ꧀ꦒꦿꦺꦏ꧀ (anggrék, "orchid"). [5] [6] [7] [8]

Description

Angraecums are quite varied vegetatively and florally, and are adapted to dry tropical woodland habitat and have quite fleshy leaves as a consequence. Most are epiphytes, but a few are lithophytes.

The long-lasting flowers are racemose and grow from the leaf axils. They are mostly white, but a few are yellow, green or ochre. They all have a long spur at the back of the labellum (lip).

In the case of Angraecum sesquipedale , a species from Madagascar, on observing the 30 centimetres (12 in) spur in the lip, Charles Darwin made the hypothesis that, since the nectar was at the bottom of the spur, a pollinator must exist with a tongue at least that long. Otherwise the orchid could never be pollinated. At the time, he was not believed. However, in 1903, the predicted pollinator was discovered, a hawk moth then named Xanthopan morganii praedicta ("praedicta" meaning "the predicted one"). It has an appropriately long proboscis. The specific name sesquipedale means "one foot and a half", referring to the length of the spur. This is an example of mutual dependence of an orchid and a specific pollinator.

Distribution

Tropical Africa and Madagascar contain the majority of the genus with one outlier found on Sri Lanka, and three species once thought to belong to the genus in Japan and the Philippines. But these orchids can also be found on the Comoros, the Seychelles, and the Mascarenes. They occur between sea level and 2,000 metres (6,600 ft) in humid regions.

Ecology

Pollination

The most commonly known example of Angraecum pollination is the relationship of Angraecum sesquipedale , which is pollinated by the moth species Xanthopan morganii praedicta [9] However, different modes of pollination are known to occur in Angraecum. Bird pollination has been reported to occur in Angraecum striatum , which is pollinated by the bird species Zosterops borbonicus Boddaert. [10] [11] Angraecum cadetii is pollinated by the cricket species Glomeremus orchidophilus . [12] [13] There have also been speculations regarding pollination of Angraecum cadetii Bosser and Angraecum bracteosum Balf. & S. Moore through the lizard species Phelsuma borbonica [14]

Conservation

Many species of Angraecum orchid are considered to be at risk of extinction in the wild and are protected from international trade under CITES. [15] The genus Angraecum is listed as one of the top conservation priorities by the International Union for Conservation of Nature and Natural Resources (IUCN) Orchid Specialist Group. Many of the species, such as Angraecum sororium, are endemic to Madagascar and are threatened from over collecting, loss of hawkmoth pollinators, habitat fragmentation, and fire. [16]

Horticulture

In horticulture the generic name is abbreviated as Angcm. [17] [5] Like all other orchids it is best to water in the mornings to avoid fungal rot due to overnight dampness. Feeding as per other orchids and similar light conditions: in humid and hot regions (sub tropical) feed fortnightly during growing season (Summer) with a certified orchid fertiliser following directions on packet, weaker solutions are also okay if you're worried. In summer water weekly or more depending on situation. Angraecums flower best when in a lighter position. Keep out of direct sunlight as this can damage (and eventually kill) the plant. Most Angraecums will have their leaves for a number of years so any sun burn spots are ugly for a significant period and also may expose your plant to disease. In indirect sunlight the Angraecums will reward you with blooms and attractive growth.

Angraecum Veitchii: a very rewarding orchid. In indirect light and watered/fed regularly this plant will produce blooms annually (usually in late Winter to Spring - for Australia this occurs in August). The flowers last a while if kept in a sheltered position and their strong heady fragrance is delightful. They only release their perfume at night. Flowers are large (4–9 centimetres (1.6–3.5 in) across), waxy, white to greenish cream in colour and borne on stems of seven to ten depending on the faithfulness of your fertilising, watering, and indirect light provision. The leaves are large, thick straps that alternately fan out from a central (monopodal) stem. Pups (keikis) form at the base of the stem and can either be divided from the parent plant once they have at least three roots of their own or alternatively, left on the plant these will make a stunning specimen as when mature will produce blooms with the parent plant - many award-winning angraecum veitchiis are grown as such. In the right conditions these orchids are healthy and require little attention. As they are epiphytes the potting mixture should be loose and free draining. Prolific roots are formed from the base and also amongst the lower half of the foliage. These can be troublesome when moving the plant. Once your angraecum is big it is best to pot it in a heavy terracotta pot or place a brick in the bottom of the pot in order to ensure the plant does not get top heavy and risk snapping when blown over in the wind, especially since they flower during the windier times of the year. When watering a good soaking with a hose or watering-can is best (not just a misting from a spray gun) as this helps to flush away any salts from fertilisers that may be present in the potting mixture and also thoroughly wets the plant. Make sure the roots halfway up the stem get a soaking too, not just the potted roots.

Hybrids

Related Research Articles

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<span class="mw-page-title-main">Predictive power</span> Ability of a scientific theory to generate testable predictions

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<span class="mw-page-title-main">Pollination syndrome</span> Flower traits that attract pollinators

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<i>Amesiella</i> Genus of orchids

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<i>Angraecum sesquipedale</i> Species of orchid

Angraecum sesquipedale, also known as Darwin's orchid, Christmas orchid, Star of Bethlehem orchid, and king of the angraecums, is an epiphytic orchid in the genus Angraecum endemic to Madagascar. The orchid was first discovered by the French botanist Louis-Marie Aubert du Petit-Thouars in 1798, but was not described until 1822. It is noteworthy for its long spur and its association with the naturalist Charles Darwin, who surmised that the flower was pollinated by a then undiscovered moth with a proboscis whose length was unprecedented at the time. Darwin's prediction went unverified for 21 years after his death, until just such a moth was discovered and his conjecture vindicated. The story of its postulated pollinator has come to be seen as one of the celebrated predictions of the theory of evolution.

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<i>Xanthopan</i> Genus of moths

Xanthopan is a monotypic genus of sphinx moth, with Xanthopan morganii, commonly called Morgan's sphinx moth, as its sole species. It is a very large sphinx moth from Southern Africa and Madagascar. Little is known about its biology, though the adults have been found to visit orchids and are one of the main pollinators of several of the Madagascar endemic baobab (Adansonia) species, Adansonia perrieri or Perrier's baobab.

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<i>Aerangis fastuosa</i> Species of orchid

Aerangis fastuosa, commonly known as the 'magnificent Aerangis', is a species of epiphytic orchid endemic to Madagascar. It is widespread across Madagascar, stretching from the eastern coastal forests across to the south and along the central plateau. Aerangis fastuosa belongs to the family Orchidaceae, subtribe Aerangidinae.

<i>Angraecum eburneum</i> Species of orchid

Angraecum eburneum is a species of orchid. Their common name the "comet orchid". They generally grow up to 2 metres in height and grows 10 to 15 flowers per plant. They are native to Madagascar, Comoros, Seychelles, Réunion, Mauritius, Kenya, and Tanzania. It is the national flower of Seychelles.

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<i>Angraecum cadetii</i> Species of orchid

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<i>Coelonia solani</i> Species of moth

Coelonia solani is a moth of the family Sphingidae. It is known from Mauritius, Réunion, Madagascar and the Comoro Islands. It is a pollinator of some species of baobab in Madagascar, including Adansonia za.

Glomeremus orchidophilus is a recently (2010) discovered species of raspy cricket found in the island of Réunion in the Mascarene Islands. It is the only known pollinator of the orchid Angraecum cadetii. It is also the only cricket known to pollinate a flower.

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<i>Angraecum longicalcar</i> Species of plant

Angraecum longicalcar, also known as the long spurred Angraecum, is a large critically endangered orchid endemic to the Central Highlands of Madagascar. This lithophytic species is noteworthy for its exceptionally long 40 cm nectar spur, rivalling that of the famous Darwins' orchid , and as such may have the longest spur of any orchid species.

References

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  2. Darwin Orchid (Comet Orchid, Star of Bethlehem). (2019, August 14). Gothenburg Botanical Garden. Retrieved January 16, 2023, from https://www.botaniska.se/en/research--collections/collections/tropical-orchids/darwin-orchid-comet-orchid-star-of-bethlehem/
  3. Comet Orchid at the Orchid Room. (n.d.). Friends of the Port St Lucie Botanical Gardens. Retrieved January 16, 2023, from https://www.pslbg.org/comet-orchid.html
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  10. Micheneau, C., Fournel, J., Humeau, L., & Pailler, T. (2008). "Orchid–bird interactions: a case study from Angraecum (Vandeae, Angraecinae) and Zosterops (white-eyes, Zosteropidae) on Reunion Island." Botany, 86(10), 1143-1151.
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  12. Micheneau, C., Fournel, J., Warren, B. H., Hugel, S., Gauvin-Bialecki, A., Pailler, T., ... & Chase, M. W. (2010). "Orthoptera, a new order of pollinator." Annals of botany, 105(3), 355-364.
  13. Fournel, J., Micheneau, C., & Baider, C. (2015). "A new critically endangered species of Angraecum (Orchidaceae), endemic to the island of Mauritius, Indian Ocean." Phytotaxa, 222(3), 211-220.
  14. Bègue, J. F., Sanchez, M., Micheneau, C., & Fournel, J. (2014). "New record of day geckos feeding on orchid nectar in Reunion Island: can lizards pollinate orchid species?." Herpetology Notes, 7, 689-692.
  15. Angraecum. (n.d.). Convention on International Trade in Endangered Species of Wild Fauna and Flora. Retrieved January 16, 2023, from https://cites.org/eng/taxonomy/term/13325
  16. Whitman, Melissa; Medler, Michael; Randriamanindry, Jean Jacques; Rabakonadrianina, Elisabeth (April 2011). "Conservation of Madagascar's granite outcrop orchids: influence of fire and moisture" (PDF). Lankesteriana. 11 (1): 55–67. doi:10.15517/lank.v11i1.18315. ISSN   1409-3871.
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