Labellum (botany)

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Showy lady slipper (Cypripedium reginae) has a pink labellum Cypripedium reginae.jpg
Showy lady slipper (Cypripedium reginae) has a pink labellum
P: Petalum
S: Sepalum
L: Labellum Labelle orchidee.png
P: Petalum
S: Sepalum
L:Labellum

In botany, the labellum (or lip) is the part of the flower of an orchid or Canna , or other less-known genera, that serves to attract insects, which pollinate the flower, and acts as a landing platform for them.

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Labellum (plural: labella) is the Latin diminutive of labrum, meaning lip.

The labellum is a modified petal and can be distinguished from the other petals and from the sepals by its large size and its often irregular shape. It is not unusual for the other two petals of an orchid flower to look like the sepals, so that the labellum stands out as distinct. [1]

In orchids, the labellum is the modified median petal that sits opposite from the fertile anther and usually highly modified from the other perianth segments. It is often united with the column and can be hinged or movable, facilitating pollination. Often, the orchid labellum is divided into three or more lobes. Some have modified fleshy lumps on the upper surface generally referred to as the callus (plural: calli), with some being divided into multiple ridges or a central keel. When the callus is flat and broad, it is sometimes called a plate, which can have fringed margins. The callus can be highly modified with striking colors that may aid in pollinator deceit and mimicry. [2] [3]

The labellum in orchids is often large and complex enough that terminology describing relative positions for structures on it becomes useful: the hypochile is the basal portion nearer the connection with the rest of the flower, the mesochile is the middle portion, and the epichile is the distal portion. [2]

See also

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<i>Caladenia</i> Genus of orchids

Caladenia, commonly known as spider orchids, is a genus of 350 species of plants in the orchid family, Orchidaceae. Spider orchids are terrestrial herbs with a single hairy leaf and a hairy stem. The labellum is fringed or toothed in most species and there are small projections called calli on the labellum. The flowers have adaptations to attract particular species of insects for pollination. The genus is divided into three groups on the basis of flower shape, broadly, spider orchids, zebra orchids and cowslip orchids, although other common names are often used. Although they occur in other countries, most are Australian and 136 species occur in Western Australia, making it the most species-rich orchid genus in that state.

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<i>Prasophyllum</i> Genus of flowering plants

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<i>Caladenia flava</i> Species of orchid

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<i>Bifrenaria</i> Genus of orchids

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<i>Epidendrum denticulatum</i> Species of orchid

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<i>Calochilus</i> Genus of orchids

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<i>Genoplesium</i> Genus of orchids

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<i>Leporella</i> Genus of orchids

Leporella fimbriata, commonly known as hare orchid or fringed hare orchid, is the only species in the flowering plant genus Leporella in the orchid family, Orchidaceae and is endemic to the southern Australia mainland. It is related to orchids in the genus Caladenia but has an unusual labellum and does not have hairy leaves. Its pollination mechanism is also unusual.

<i>Lyperanthus</i> Genus of orchids

Lyperanthus, commonly known as beak orchids, is a genus of flowering plants from the orchid family, Orchidaceae, that is endemic to Australia. There are two species, one in Western Australia and the other in four eastern Australian states, distinguished by their single long, narrow, leathery leaf and dull coloured flowers which have prominent short calli on their labellum. Both form loose colonies which reproduce asexually from their tubers, and sexually using their flowers.

<i>Caleana</i> Genus of flowering plants

Caleana, commonly known as duck orchids, is a genus of flowering plants in the orchid family, Orchidaceae that is found in Australia and New Zealand. The Australian species are found in all states but have not been recorded in the Northern Territory. Duck orchids have a single leaf and one or a few, dull-coloured, inconspicuous flowers. Most species are found in Western Australia but one species occurs in eastern Australia and one occurs in eastern Australia and New Zealand. Orchids in this genus as well as the hammer orchids (Drakaea) are pollinated by male thynnid wasps.

<i>Arthrochilus latipes</i> Species of flowering plant

Arthrochilus latipes, commonly known as robust elbow orchid, is a flowering plant in the orchid family (Orchidaceae) and is endemic to the "Top End" of the Northern Territory in Australia. Each plant has from two to four ground-hugging leaves and between three and fifteen flowers during the wet season and the species often forms spreading colonies on sandstone escarpments. Like others in the genus, the flowers are pollinated by a species of thynnid wasp.

Caladenia atrochila is a plant in the orchid family Orchidaceae and is endemic to Tasmania. It is a ground orchid with a single hairy leaf and flowers that are whitish or pinkish on the front, but yellowish-green on the back and a cream-coloured labellum with dark red markings.

Caladenia bicalliata subsp. bicalliata, commonly known as the limestone spider orchid or dwarf limestone spider orchid, is a plant in the orchid family Orchidaceae and is native to the south-west of Western Australia and coastal areas of South Australia. It has a single erect, hairy leaf and one or two cream-coloured flowers with reddish-brown tips.

<i>Caladenia caudata</i> Species of orchid

Caladenia caudata, commonly known as tailed spider orchid, is a plant in the orchid family Orchidaceae and is endemic to Tasmania. It is a ground orchid with a single hairy leaf and up to four red, or yellow and red flowers with dark red to almost black tips.

<i>Diuris brevifolia</i> Species of orchid

Diuris brevifolia, commonly known as the short-leaved donkey orchid, is a species of orchid which is endemic to South Australia. It has a few narrow, twisted leaves and a flowering stem with up to five bright yellow flowers with brown markings and relatively large, spreading lobes on the labellum. This is a relatively late-flowering species of donkey orchid.

Diuris heberlei, commonly called Heberle's donkey orchid, is a species of orchid which is endemic to the south-west of Western Australia. It has three to five linear leaves at its base and up to four bright yellow flowers with a reddish brown border around the labellum callus. It is found along the south coast and is one of the last Diuris to flower in Western Australia.

References

  1. Bailey, L. H. Gentes Herbarum: Canna x orchiodes. (Ithaca), 1 (3): 120 (1923); Khoshoo, T. N. & Guha, I. Origin and Evolution of Cultivated Cannas. Vikas Publishing House.
  2. 1 2 Dressler, R.L. 1993. Phylogeny and Classification of the Orchid Family. Portland, Oregon: Dioscorides Press. pp. 29-30.
  3. Kurzweil, Hubert; Kocyan, Alexander (2002). "Ontogeny of orchid flowers". In Kull, Tiiu; Arditti, Joseph (eds.). Orchid Biology: Reviews and Perspectives, VIII. Kluwer Academic Publishers. pp. 83–138. ISBN   1-4020-0580-6.