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.
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]
Miltonia, abbreviated Milt. in the horticultural trade, is an orchid genus comprising twelve epiphyte species and eight natural hybrids. The miltonias are exclusively inhabitants of Brazil, except for one species whose range extends from Brazil into the northeast of Argentina and the east of Paraguay.
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.
Leptotes, abbreviated Lpt in horticultural trade, is a genus of orchids formed by nine small species that grow in the dry jungles of south and southeast Brazil, and also in Paraguay or Argentina. They are small epiphytic plants of caespitose growth that sometimes resemble little Brassavola, as they share the same type of thin terete leaves, though they are more closely related to Loefgrenianthus.
Prasophyllum, commonly known as leek orchids, is a genus of about 140 species of flowering plants in the orchid family, Orchidaceae and is found in Australia and New Zealand. The Australian species are found in all states but have not been recorded in the Northern Territory. The common name arises from their having a hollow, leek- or onion-like leaf. Some species only flower after summer fires and have flowers similar to those of Xanthorrhoea which flower at the same time, suggesting that they employ the same pollinating insects. Leek orchids are similar to those in the genus Genoplesium except that the free part of the leaf is cylindrical and the labellum has a solid connection to the column. They range in size from the little laughing leek orchid at about 15 cm (6 in) to the king leek orchid which grows up to 2 m (80 in) tall.
Caladenia flava, commonly known as cowslip orchid, is a species of orchid endemic to the south-west of Western Australia. It is a relatively common orchid with a single, hairy leaf and up to three yellow flowers which often have red markings. In 2001 three subspecies were named and a fourth is recognised but not as yet formally described.
Bifrenaria, abbreviated Bif. in horticultural trade, is a genus of plants in family Orchidaceae. It contains 20 species found in Panama, Trinidad and South America. There are no known uses for them, but their abundant, and at first glance artificial, flowers, make them favorites of orchid growers.
Epidendrum denticulatum, one of the crucifix orchids, is a reed stemmed species which, at least in herbarium specimens, is frequently confused with E. secundum Jacq.
Acriopsis emarginata, commonly known as the pale chandelier orchid, is a species of orchid endemic to Queensland. It is a clump-forming epiphyte with dark green leaves and curved, branching flower stems with many white and cream-coloured flowers.
Arthrochilus, commonly called elbow orchids, is a genus of about fifteen species of flowering plants from the orchid family (Orchidaceae) and is found in Australia and New Guinea. The flowers are pollinated by male thynnid wasps which attempt to mate with the flower and are held in place by hooks while the pollinium is transferred between insect and flower.
Calochilus, commonly known as beard orchids, is a genus of about 30 species of plants in the orchid family, Orchidaceae. Beard orchids are terrestrial herbs with a single leaf at the base of the plant, or no leaves. Their most striking feature is a densely hairy labellum, giving rise to their common name. Beard orchids, unlike some other Australian orchids, do not reproduce using daughter tubers, but self-pollinate when cross-pollination has not occurred. Most species occur in Australia but some are found in New Zealand, New Guinea and New Caledonia.
Genoplesium commonly known as midge orchids, is a genus of about 50 species of flowering plants in the orchid family, Orchidaceae and is found in Australia, New Zealand and New Caledonia. Midge orchids are terrestrial herbs with a single leaf at the base of the plant. They are similar to orchids in the genus Prasophyllum in that plants without flowers have a hollow, onion-like leaf. The flowers are small but often scented and attractive to their insect pollinators. There is disagreement about which species belong to this genus and some taxonomists suggest that most belong in the genus Corunastylis.
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.
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.
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.
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.
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.
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.
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