''Caladenia sigmoidea'', commonly known as the sigmoid 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 erect, hairy leaf and usually only one red and cream-coloured flowers with an unusual S-shaped
labellum.
Description
''Caladenia sigmoidea'' 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 about wide. Usually only one red and cream-coloured flower, long and wide is borne on a stalk tall. 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 ...
s have thick, brown, club-like
glandular tips long. The
dorsal sepal is erect, long and about wide. The lateral sepals are long and about wide and curve stiffly downwards. The petals are long, about wide and curve stiffly upwards. The labellum is long, wide and creamy white with red stripes. The sides of the labellum have up to six short teeth on each side and there are two rows of red, anvil-shaped
calli along its mid-line. The shape of the labellum is unusual in that it curves downward but with the tip turned up, producing an S-shape when viewed from the side. Flowering is from August to September.
Taxonomy and naming
''Caladenia sigmoidea'' was first formally described by
Richard Rogers
Richard George Rogers, Baron Rogers of Riverside (23 July 1933 – 18 December 2021) was a British architect noted for his modernist and Functionalism (architecture), functionalist designs in high-tech architecture. He was a senior partner a ...
in 1938 from a specimen collected at Kumarl near
Salmon Gums
Salmon () is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic (genus '' Salmo'') and North Pacific (genus ''Oncorhynch ...
, and the description was published in ''
''.
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 ...
(''sigmoidea'') is "from the Latin ''sigmoideus'' (sigmoid, curved like the letter S), alluding to the sigmoid shaped labellum".
Distribution and habitat
The sigmoid spider orchid is widespread between
Mount Jackson and
Mount Ragged in the
Avon Wheatbelt,
Coolgardie 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 on stony hills, woodland and on granite outcrops.
Conservation
''Caladenia sigmoidea'' 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=Q9673958
sigmoidea
Orchids of Western Australia
Endemic orchids of Australia
Plants described in 1938
Endemic flora of Western Australia