''Caladenia horistes'', commonly known as the cream spider orchid, is a species of orchid 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 se ...

of Western Australia. It has a single, hairy leaf and one or two, creamy-yellow flowers which have a red-striped labellum and long, dark, thread-like tips on the sepals and

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 ...

Description

''Caladenia horistes'' 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 an underground tuber and a single erect, hairy leaf, long and wide. One or two flowers long and wide are borne on a stalk tall. The flowers are cream-coloured to creamy-yellow and the sepals and petals spread horizontally but have long, drooping, dark, thread-like tips. The dorsal sepal is erect, long and wide at the base and the lateral sepals are about the same size. The petals are long and about wide. The labellum is long and wide and a similar colour to the sepals and petals but with pale brown or red lines and blotches. The sides of the labellum have short teeth, the tip is turned downwards and there are two rows of cream to yellowish, anvil-shaped calli along its centre. Flowering occurs from August to early October.

Taxonomy and naming

''Caladenia horistes'' was first described in 2001 by

Stephen Hopper Stephen Donald Hopper AC FLS FTSE (born 18 June 1951) is a Western Australian botanist. He graduated in Biology, specialising in conservation biology and vascular plants. Hopper has written eight books, and has over 200 publications to his n ...

and

Andrew Phillip Brown Andrew Phillip Brown (born 1951) is a conservation biologist and taxonomist at the Western Australian Department of Environment and Conservation. He is also curator of Orchidaceae and Myoporaceae Myoporaceae was a family of plants, found mostly ...

from a specimen collected in the Wittenoom Hills north of Esperance and the description was published in '' Nuytsia''. 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 ...

(''horistes'') is an Ancient Greek word meaning "definer of boundaries" referring to the distribution of this species being at the easterly limit distribution of orchids similar to this species.

Distribution and habitat

The cream spider orchid occurs between the Fitzgerald River National Park and Balladonia in the Avon Wheatbelt, Coolgardie, Esperance Plains, Jarrah Forest and Mallee

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 ...

where it grows in shrubland near creeks and around granite outcrops.

Conservation

''Caladenia horistes'' 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=Q9673674 horistes Orchids of Western Australia Endemic orchids of Australia Plants described in 2001 Endemic flora of Western Australia Taxa named by Stephen Hopper Taxa named by Andrew Phillip Brown