Leek orchids | |
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P. petilum growing in the Australian Capital Territory | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Asparagales |
Family: | Orchidaceae |
Subfamily: | Orchidoideae |
Tribe: | Diurideae |
Subtribe: | Prasophyllinae |
Genus: | Prasophyllum R.Br. (1810) |
Type species | |
Prasophyllum australe | |
Diversity | |
About 140 species | |
Synonyms [2] | |
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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 (flat in Genoplesium) and the labellum has a solid (rather than flexible) connection to the column. They range in size from the little laughing leek orchid ( P. gracile ) at about 15 cm (6 in) to the king leek orchid ( P. regium ) which grows up to 2 m (80 in) tall.
Orchids in the genus Prasophyllum are terrestrial, perennial, deciduous, sympodial herbs usually with a few inconspicuous, fine roots and a pair of more or less spherical tubers partly covered by a fibrous sheath. Replacement tubers form at the end of short root-like stolons. Leek orchids rarely reproduce by forming "daughter" tubers, relying on their flowers for reproduction. A single onion or leek-like leaf develops near the base of the plant and accounts for the common name of the group. The leaf is long, narrow, hollow, cylindrical and glabrous. [3] [4] [5] [6] [7]
The inflorescence is a spike or raceme with a few to many non-resupinate flowers breaking through a thin part of the leaf. The dorsal sepal is wider than two lateral sepals which are often joined. The petals are often curved, shorter and narrower than the sepals. As is usual in orchids, one petal is highly modified as the central labellum, differing markedly from the other petals and sepals. The labellum is positioned above the column and rigidly attached to its base. Its edges are usually wavy and rolled back. The labellum has a callus which consists of a raised, fleshy plate which is usually channelled, with the base forming an inverted basin shape. The sexual parts of the flower are fused to the column which is short and has narrow wings, often with a small lobe at the front. Leek orchids usually flower between late winter and early summer, depending on species, and the fruit that follows flowering is a non-fleshy, dehiscent capsule containing up to 500 seeds. [3] [4] [5] [6] [7]
The genus Prasophyllum was first formally described by Robert Brown in 1810 and the description was published in Prodromus Florae Novae Hollandiae . [8] [9] Brown described twelve species but did not name a type species, however in 1989, Mark Clements nominated P. australe as the lectotype. [1]
The name Prasophyllum is derived from the Ancient Greek words prason meaning "leek" [10] : 573 and phyllon meaning "leaf". [10] : 466
Leek orchids occur in all states of Australia, but not in the Northern Territory. There are 20 named species in Western Australia as well as a further 40 that have been discovered but not as yet described. [4] There are 28 species in Tasmania, [3] about 40 in New South Wales [7] and 15 in South Australia. [11] New Zealand has about 6 species, occurring on both main islands as well as Stewart and Chatham Islands. [5] [12] In Western Australia alone, they grow in a range of habitats from the margins of salt lakes, to swamps and dense Karri ( Eucalyptus diversicolor ) forests. [4]
Prasophyllum species are mycotrophic, requiring symbiotic fungi for seed germination. The main fungus is Ceratobasidium cornigerum . [13] [14]
Many Western Australian species only flower after summer fires and in other years only produce leaves. Most flowers are strongly scented, produce nectar and are pollinated by insects but a few appear able to self-pollinated if not visited. They often have flowers similar to grass trees in the genus Xanthorrhoea , flower under similar conditions and are visited by a similar range of insects, suggesting that they mimic grass tree flowers. [4] [5]
As at October 2017, about 140 species are recognised by the World Checklist of Selected Plant Families. Eight species described in 2017 are not included on the Checklist yet but are included in the International Plant Names Index. They are P. crassum, P. nitidum, P. roseum, P. rousei, P. stygium, P. sylvicola, P. spadiceum and P. tortilis. [2] [15]
See List of Prasophyllum species
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.
Microtis, commonly known as onion orchids or mignonette orchids is a genus of about 20 species of plants in the orchid family, Orchidaceae. Onion 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 they have an onion-like leaf. The flowers are small but often scented and attractive to their insect pollinators. They are widespread in Asia, Australia and some Pacific islands.
Cyrtostylis, commonly known as gnat orchids, is a genus of five or six species of flowering plants in the orchid family Orchidaceae and is native to Australia and New Zealand. Cyrtostylis orchids often form dense colonies of genetically identical plants. They have a single heart-shaped leaf and a thin flowering stem with pale coloured insect-like flowers. The lateral sepals and petals are similar in size and colour but the labellum is shelf-like and conspicuous with two prominent glands at its base.
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.
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.
Pheladenia deformis, commonly known as blue fairy orchid or blue beard is the only species of the flowering plant genus Pheladenia in the orchid family, Orchidaceae and is endemic to Australia. It was originally named as Caladenia deformis and has since had several name changes. Plants have a single, narrow, hairy leaf and usually blue flowers with relatively short, broad sepals and petals and an unusual labellum.
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.
Genoplesium fimbriatum, commonly known as the fringed midge orchid is a small terrestrial orchid found from southern Queensland to southern New South Wales. It has a single thin leaf and up to thirty green to brownish-green flowers with red stripes and a red-tipped labellum with hairy edges.
Prasophyllum alpinum, commonly known as the alpine leek orchid, is a species of orchid endemic to Tasmania. It was formerly described as occurring in mainland Australia but has smaller flowers than the species occurring there. It has a single, tube-shaped leaf and up to fourteen green to greenish-brown flowers and grows in subalpine areas.
Microtis parviflora, commonly known as the slender onion-orchid, is a species of orchid which is native to Australia and New Zealand. It occurs in all states of Australia but is not known from the Northern Territory and may not occur in Western Australia. As with others in the genus, it has a single erect, smooth, tubular leaf and up to eighty flowers on an erect flower spike.
Prasophyllum australe, commonly known as the southern leek orchid or austral leek orchid, is a species of orchid and is endemic to south-eastern Australia. It has a single tubular, green leaf and up to fifty scented, greenish-brown flowers with red stripes.
Prasophyllum colensoi is a species of orchid endemic to New Zealand where it is commonly known as the leek orchid. It has a single tubular, dark green leaf and up to twenty scented, yellowish-green to reddish-brown flowers. It is similar to P. hectori, the only other species of Prasophyllum found in New Zealand, but is distinguished from it by its smaller size, fewer flowers and different habitat.
Prasophyllum fuscum, commonly known as the slaty leek orchid or tawny leek orchid, is a species of orchid endemic to a small region of New South Wales. It has a single tubular green leaf and up to thirty greenish brown to reddish brown flowers. There is debate about the taxonomy of the species with some authorities considering Prasophyllum uroglossum as a separate species. Only about twenty five plants are known to survive in south-western Sydney.
Prasophyllum gibbosum, commonly known as the humped leek orchid, is a species of orchid endemic to the south-west of Western Australia. It is a late-flowering leek orchid with a single smooth, tubular leaf and up to eighty or more purplish-red and white flowers with a smooth labellum. It is similar to P. cucullatum but that species has a frilly labellum, usually a shorter flowering stem and an earlier flowering period.
Prasophyllum macrostachyum, commonly known as the laughing leek orchid, is a species of orchid endemic to the south-west of Western Australia. It has a single smooth, tube-shaped leaf and up to thirty yellowish-green and purple flowers. It is one of the few Western Australian leek orchids which is not stimulated by summer fires and also has an unusually long flowering period.
Prasophyllum patens, commonly known as the broad-lipped leek orchid or sandstone leek orchid, is a species of orchid endemic to the Sydney region of New South Wales. It has a single tubular green leaf and up to thirty green to greenish-brown, lemon-scented flowers with a white labellum.
Prasophyllum striatum, commonly known as the streaked leek orchid, is a species of orchid endemic to New South Wales. It has a single thin, tube-shaped leaf and up to ten greenish and whitish flowers with reddish or purplish stripes. It differs from other leek orchids in having a very thin leaf and prominently streaked flowers.
Genoplesium rufum, commonly known as the rufous midge-orchid, is a species of orchid endemic to New South Wales. It has a single thin, wiry leaf and up to twenty five drooping, pinkish or reddish flowers on a flowering stem which is fused to the lower part of the leaf. It was formerly thought to range from Queensland to South Australia and Tasmania but specimens in other states are now assigned to Genoplesium clivicola.
Genoplesium baueri, commonly known as the brittle midge orchid, is a small terrestrial orchid which is endemic to New South Wales. It has a single thin leaf and up to nine yellowish green to reddish brown flowers. It is mostly only found in coastal and near-coastal heath and woodland between Port Stephens and Ulladulla.