''Caladenia'', commonly known as spider orchids, is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of 350

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s in the orchid

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Orchidaceae Orchids are plants that belong to the family (biology), family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan distribution, cosmopolitan plants that ...

. Spider orchids are

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

herbs Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnish (food), garnishing food, for medicinal purposes, or for fragrances. Culinary use typi ...

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 Pollination is the transfer of pollen from an anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or bu ...

. 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 Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

, making it the most species-rich orchid genus in that state.

Description

Orchids in the genus ''Caladenia'' are terrestrial,

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

sympodial In botany, sympodial growth is a bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, als ...

herbs with a few inconspicuous, fine roots and a

tuber Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reproduc ...

partly surrounded by a fibrous sheath. The tuber produces two "droppers" which become daughter tubers in the following year. There is a single hairy convolute leaf at the base of the plant. Most species have an enlarged cell at the base of each hair. The leaf may be medium-sized to large, fleshy or leathery, lance-shaped to oblong, but is always

simple Simple or SIMPLE may refer to: *Simplicity, the state or quality of being simple Arts and entertainment * ''Simple'' (album), by Andy Yorke, 2008, and its title track * "Simple" (Florida Georgia Line song), 2018 * "Simple", a song by John ...

, lacking lobes and serrations. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a

raceme A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are ...

with from one to eight resupinate

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s. The three

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s and two

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s are free and similar in size and shape to each other. In some species, the sepals or petals or both have narrow tips with club-like ends. As is usual in orchids, one petal is highly modified as the central labellum. The labellum is divided into three parts, each of which usually has a fringed or dentate margin, while the central lobe has stalked or button-like calli which are often in rows. The sexual parts of the flower are fused to the

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...

, which has wing-like structures on its sides. Most species flower in early spring but some species, such as the winter spider orchid ('' C. drummondii'') flower in other months. The fruit that follows flowering is a non-fleshy,

dehiscent Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part. Structures that op ...

capsule containing up to 500 seeds. Kwinana gnangarra 300815-102

Taxonomy and naming

The first specimens of the genus were collected by

Joseph Banks Sir Joseph Banks, 1st Baronet, (19 June 1820) was an English Natural history, naturalist, botanist, and patron of the natural sciences. Banks made his name on the European and American voyages of scientific exploration, 1766 natural-history ...

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

in 1777 and by

Archibald Menzies Archibald Menzies ( ; 15 March 1754 – 15 February 1842) was a Scottish surgeon, botanist and naturalist. He spent many years at sea, serving with the Royal Navy, private merchants, and the Vancouver Expedition. During his naval expeditions, h ...

King George Sound King George Sound (Mineng ) is a sound (geography), sound on the south coast of Western Australia. Named King George the Third's Sound in 1791, it was referred to as King George's Sound from 1805. The name "King George Sound" gradually came in ...

in Western Australia in 1784. James Edward Smith formally described ''Arethusa catenata'', now known as ''

Caladenia catenata ''Caladenia catenata'', commonly known as white caladenia, white fingers and lady's fingers, is a plant in the orchid family Orchidaceae and is endemic to New South Wales, Queensland and Victoria. It is a ground orchid with a single hairy leaf ...

'' in 1805, from specimens collected in Sydney. The genus was first formally described by

Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and author Entertainers and artists * Washboard Sam or Robert Brown (1910–1966), American musician and singer * Robert W. Brown (1917–2009), American printmaker ...

in 1810 in ''

Prodromus Florae Novae Hollandiae ''Prodromus Florae Novae Hollandiae et Insulae Van Diemen'' (Prodromus of the Flora of New Holland and Van Diemen's Land) is a book by the botanist Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and ...

''. At the same time he described 15 species of ''Caladenia'' but did not nominate a

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

. Brown collected the specimens as a member of

Matthew Flinders Captain (Royal Navy), Captain Matthew Flinders (16 March 1774 – 19 July 1814) was a British Royal Navy officer, navigator and cartographer who led the first littoral zone, inshore circumnavigate, circumnavigation of mainland Australia, then ...

' mapping and exploration voyage that circumnavigated

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. He spent just over three years on botanical research with assistants in Australia. The genus name (''Caladenia'') is derived from the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

words ''kalos'' meaning "beautiful" and ''aden'' meaning "a gland" referring to the colourful labellum. There has been disagreement between taxonomists as to which orchids belong in the genus ''Caladenia'' and which do not, and about classification within the genus. Recent studies of the

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

of the group suggest that

John Lindley John Lindley Fellow of the Royal Society, FRS (5 February 1799 – 1 November 1865) was an English botanist, gardener and orchidology, orchidologist. Early years Born in Old Catton, Catton, near Norwich, England, John Lindley was one of four c ...

’s 1840 description of ''Caladenia'' (in ''The Genera and Species of Orchidaceous Plants''), but including ''

Glossodia ''Glossodia'', commonly known as waxlip orchids, is a genus of mostly purple orchids from Australia. The genus was first formally described in 1810 by the prolific Scottish botanist Robert Brown (botanist, born 1773), Robert Brown who publishe ...

'' and ''

Elythranthera ''Elythranthera'', commonly known as enamel orchids, is a genus of flowering plants in the orchid family, Orchidaceae. It contains two species and a named hybrid, all endemic to the south-west of Western Australia. The genus was first formally d ...

'', as being the most accurate reflection of the subtribe ''

Caladeniinae Caladeniinae is an orchid subtribe in the tribe Diurideae. See also * Taxonomy of the Orchidaceae References

Caladeniinae, Orchid subtribes {{Orchidoideae-stub ...

''. Those orchids previously included in the genera ''Glossodia'', ''Elythranthera'' and ''Cyanicula'' have been transferred to ''Caladenia''. Caladenia orchids are informally grouped into those with long narrow sepals and petals, such as the white spider orchid ('' C. longicauda'') and the clubbed spider orchid ('' C. longiclavata''), those with short sepals and petals which tend to hang near the stem, such as the zebra orchid ('' C. cairnsiana'') and dwarf zebra orchid ('' C. pachychila'') and a third group with short, spreading sepals and petals such as the cowslip orchid ( ''C. flava'') and fan orchid ( ''C. nana'').

Distribution and habitat

Most caladenias are

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Australia. Eleven species, ten of which are endemic, occur in

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

with one also occurring in Australia. ''

'' and '' C. carnea'' occur in

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

, with the latter also found in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. There are about 136 species endemic to the

south-west The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A ''compass rose'' is primarily composed of four cardinal directions—north, east, south, and west—each ...

of Western Australia, 114 of which have been formally described and a further 18 hybrids which have been described and named. In Western Australia, caladenias are found in the

from north of Kalbarri on the west coast to the

Nuytsland Nature Reserve Nuytsland Nature Reserve is a protected area of Western Australia in the south-eastern part of the state, on the south coast. Geography Nominally located at , it has an area of , and takes in over of coastline from Cape Pasley to Red Rocks ...

on the coast of the

Great Australian Bight The Great Australian Bight is a large oceanic bight (geography), bight, or open bay, off the central and western portions of the southern Coast, coastline of mainland Australia. There are two definitions for its extent—one by the Internation ...

. Their habitats range from cool, moist

Karri ''Eucalyptus diversicolor'', commonly known as karri, is a species of flowering plant in the family Myrtaceae and is Endemism, endemic to the Southwest Australia, south-west of Western Australia. It is a tall tree with smooth light grey to cre ...

forest, to

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

lands near the coast and to almost arid mallee

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

Ecology

Orchids in the genus ''Caladenia'' are pollinated by insects, usually bees or wasps. Some species appear to attract male wasps by having the scent, shape and colouration of flightless female wasps. For example, '' C. lobata'' attracts male '' Thynnoides bidens'' wasps. As the wasps lands on the flower, the labellum is pulled down by the insect's weight. As it moves up the labellum, that organ tips the insect against the column where the wasp contacts the sexual parts and either picks up or deposits

pollinia A pollinium (: pollinia) is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in plants such as orchids and many species of milkwee ...

. Many such orchids are only attractive to one species of insect. Sometimes hybrids between female-mimicking and food-attracting species occur as in the case of '' C. patersonii'' which has the odour of fermentation. ''C. patersonii'' attracts several insect species, and forms hybrids with insect-mimicking species including '' C. lobata'' and '' C. dilatata''. In some caladenias, the sepal and petals (apart from the labellum) are narrow with expanded tips called "clubs". These are thought to be the source of sexual attractants for those species that mimic female wasps. Most such species do not have a scent detectable by humans but are attractive to male Thynnid wasps. For some species, such as '' C. multiclavia'', it is the labellum that mimics the size, shape and presumably the scent of females.

Use in horticulture

''Caladenia'' have generally proven difficult to maintain and cultivate artificially. Some enthusiasts have had limited success by cultivating the

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

fungus that the orchid requires and by careful use of fertiliser to keep the fungus and orchid in balance. The 1889 book 'The Useful Native Plants of Australia' records that "These and other orchids have edible tubers."

Gallery

Image:Caladenia Crebra.jpg, Arrowsmith spider orchid ('' C. crebra'') Image:Kwinana gnangarra 300815-105.jpg, Clubbed spider orchid ('' C. longicauda'') budding Image:Caladenia chlorostyla LC277.jpg, White fingers ('' C. chlorostyla''), from

Image:Caladenia.PlateI.jpg, Several Caladenia species from Pelloe's ''West Australia Orchids'' Image:Caladenia atrovespa (5090971253).jpg, '' C. atrovespa'' growing near

Canberra Canberra ( ; ) is the capital city of Australia. Founded following the Federation of Australia, federation of the colonies of Australia as the seat of government for the new nation, it is Australia's list of cities in Australia, largest in ...

Image:Kwinana gnangarra 300815-100.jpg, Dancing spider ('' C. discoidea'') growing near

Perth Perth () is the list of Australian capital cities, capital city of Western Australia. It is the list of cities in Australia by population, fourth-most-populous city in Australia, with a population of over 2.3 million within Greater Perth . The ...

Image:Caladenia lobata.JPG, Butterfly orchid ('' C. lobata'') near Mount Barker Image:Caladenia venusta.JPG, Large white spider orchid ('' C. venusta'')

References

* New species in ''Orchid Research Newsletter'' No. 47 (January 2006) (Royal Botanical Gardens, Kew)

External links

*
Gallery of images
- Orchid Society of Western Australia {{Taxonbar, from=Q2720020 Diurideae genera Orchids of Australia Taxa named by Robert Brown (botanist, born 1773)