''Caladenia crebra'', commonly known as the Arrowsmith spider orchid, is a species of

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

endemic Endemism is the state of a species being found 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 found elsew ...

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 se ...

of Western Australia. It has one or two relatively large, greenish-yellow flowers whose lateral

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 The term ''sepalum'' was coined b ...

s have thin brown "clubs" on their ends.

Description

''Caladenia crebra'' is a terrestrial,

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

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 leaves, usually in the autumn; to the shedding of petals, aft ...

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 an underground tuber and a single hairy leaf, long and wide. In August or September it produces one or two flowers on the end of a stalk tall, each flower wide. The flowers are greenish-yellow, sometimes with red markings. The dorsal sepal is erect, long and wide. The lateral sepals are long, wide and may spread widely below the flower or cross each other. The sepals have thin brown "clubs" on their ends. The

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 are long, wide and curve backwards. The labellum is greenish-yellow, long, wide with many upturned, narrow teeth up to long, along its sides, often with hooks on their ends. There are many densely crowded, dark purplish, finger-like "calli" crowded in distinct rows in the central part of the labellum. Flowering occurs from August to September. The fruit 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 a large number of seeds.

Taxonomy and naming

''Caladenia crebra'' was first formally described by

Alex George Alexander or Alex George may refer to: *Alex George (botanist) (born 1939), Australian botanist * Alexander L. George (1920–2006), American political scientist * Alexander George (philosopher), American philosopher *Alex George (motorcyclist), Sc ...

in 1971 and the description was published in ''

Nuytsia ''Nuytsia floribunda'' is a hemiparasitic tree found in Western Australia. The species is known locally as moodjar and, more recently, the Christmas tree or Western Australian Christmas tree. The display of intensely bright flowers during the ...

'' from a specimen found south of Dongara. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

(''crebra'') is a

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word meaning "crowded".

Distribution and habitat

The Arrowsmith spider orchid is widespread and common between Dongara and Jurien Bay in the Geraldton Sandplains and

Swan Coastal Plain The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geol ...

biogeographic regions A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions. De ...

. It grows in shallow, sandy soil in low forest and shrubland.

Conservation

''Caladenia crebra'' is classified as "Not Threatened" by the Western Australian Government

Department of Parks and Wildlife The Department of Parks and Wildlife (DPaW) was the department of the Government of Western Australia responsible for managing lands described in the ''Conservation and Land Management Act 1984'' and implementing the state's conservation and e ...

References

{{Taxonbar, from=Q9673489 crebra Orchids of Western Australia Endemic orchids of Australia Plants described in 1971 Endemic flora of Western Australia