''Caladenia rosea'' is a plant in the orchid family Orchidaceae and is endemic to relatively inaccessible, high

lateritic Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by ...

plateaux in a high rainfall area in south-western Western Australia. It is a terrestrial orchid with a single hairy leaf and up to three pink flowers on a thin, sparsely-hairy stem. It is similar to ''

Caladenia flava ''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. ...

'' but is distinguished by the perianth being pink to dark pink with prominent red striping and spotting on the dorsal sepal and lateral

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s. ''Caladenia rosea'' mimics ''

Hypocalymma robustum ''Hypocalymma robustum'', the Swan River myrtle, is a species of shrub in the myrtle family Myrtaceae. It is endemic to the south west region of Western Australia. It usually grows up to between 0.4 and 1 metre in height. Pink flowers are ...

'' (

Myrtaceae Myrtaceae, the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All speci ...

) in terms of flowering time, colour and scent.

Description

''Caladenia rosea'' is a terrestrial, perennial, deciduous,

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

with spheroid, annually replaced tubers situated 8–15 cm below the soil surface and forming a single, hairy, linear leaf, tinged purple and usually with darker purple veining below, long and wide. There are up to three flowers borne on a slender, fine, sparsely silky-hairy

raceme A raceme ( or ) or racemoid is an unbranched, 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 produced as the s ...

, tall, with a

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

in halfway up the stem. The sepals and

s are spreading, pink throughout with various amounts of deeper pink dots and stripes. The dorsal sepal is linear to ovate lanceolate, long. The lateral sepals spathulate to ovate-lanceolate and

s ovate usually with a single darker pink stripe. The labellum is prominently trilobed with a raised yellow plate near the base of the middle lobe, yellow at the base, with rows of white calli extending from either side of the plate and the lateral lobes suffused with pink, long. Column is curved over the raised central plate, yellow with prominent white lateral wings.

Taxonomy and naming

The first formal description of this orchid was by

Kingsley Dixon Kingsley Wayne Dixon (Ph.D.) is an Australian botanist currently working as a professor at Curtin University. He was the founding Director of Science at Kings Park and Botanic Gardens, and helped to establish the laboratories there as among t ...

and

Maarten Christenhusz Dr Maarten Joost Maria Christenhusz (born 27 April 1976) is a Dutch botanist, natural historian and photographer. Career He was born in Enschede, the Netherlands, received his undergraduate and master's degrees from Utrecht University in Bi ...

in 2018, but the species was initially not adopted by Florabase. It was confused for the hybrid ''C. × spectabilis'', which does occur in the area, but has orange flowers and occurs in very small numbers, whereas this species is fertile and is known from larger populations.

Distribution and habitat

''Caladenia rosea'' grows

sympatrically In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species s ...

with ''

Caladenia lateritica ''Caladenia lateritica'', also known as white primrose orchid, is a plant in the orchid family Orchidaceae and is endemic to relatively inaccessible, high lateritic plateaux in a high rainfall area in south-western Western Australia. It is a gro ...

'' in shallow lateritic regolith that overlays massive bauxite. The open

jarrah ''Eucalyptus marginata'', commonly known as jarrah, djarraly in Noongar language and historically as Swan River mahogany, is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is a tree with roug ...

('' Eucalyptus marginata'') and marri ('' Corymbia calophylla'') woodland has an understory of ''

Banksia sessilis ''Banksia sessilis'', commonly known as parrot bush, is a species of shrub or tree in the plant genus ''Banksia'' of the family Proteaceae. It had been known as ''Dryandra sessilis'' until 2007, when the genus '' Dryandra'' was sunk into ''Ba ...

'', ''

Conostylis setosa ''Conostylis'' is a genus of perennial herbs in the Haemodoraceae family, commonly known as cone flowers. All species are endemic to the south west of Western Australia. Taxonomy The genus is the most speciose of the Haemodoraceae family, and ...

'', ''

'', '' Orthosanthus laxus'', '' Xanthorrhoea preissii'', '' Phyllanthus calycinus'' and ''

Stylidium ''Stylidium'' (also known as triggerplants or trigger plants) is a genus of dicotyledonous plants that belong to the family Stylidiaceae. The genus name ''Stylidium'' is derived from the Greek ''στύλος'' or ''stylos'' (column or pillar), wh ...

'' species.

Ecology

''Caladenia rosea'' is putatively mimicking flowers of the Swan River myrtle (''

''), which has a similar colour and scent. We assume that this orchid is pollinated by the same insects as ''

'' (probably native

bees Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamil ...

). As for ''

'', ''C. rosea'' is restricted to the shallow soils overlaying massive bauxite in a confined, high rainfall region that is now subject to strip mining for bauxite. The species is therefore threatened with extinction.

References

{{Taxonbar, from=Q65932147 rosea Plants described in 2018 Endemic orchids of Australia Orchids of Western Australia