''Caladenia atrata'', commonly known as dark caladenia is a plant in the orchid family Orchidaceae and is endemic to Tasmania. It is a ground orchid with flowers that are bright white on the front, but densely covered with black glands on the back.

Description

''Caladenia atrata'' 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 ...

which usually grows in loose groups. It has an underground tuber and a single, sparsely hairy, linear, dark green leaf, long and about wide. Up to four flowers in diameter are borne on a thin, hairy, wiry spike high. 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 and sepals are bright white on the front and densely covered with black glands on the back. The dorsal sepal is long, wide and curves forward forming a hood over 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. ...

. The petals and lateral sepals are asymmetrically linear to lance-shaped, long and about wide. The labellum is long and about wide. It is white to pinkish with purple spots and a purple tip, and egg-shaped when flattened. It has three lobes and curves forward, the lateral lobes erect, surrounding the column. There are blunt teeth on the edge of the labellum and three or four rows of stalked, purplish calli along its mid-line. The

is about long and greenish with red blotches. Flowering occurs from late October to December.

Taxonomy and naming

''Caladenia atrata'' was first formally described by David Jones in 1994 and the description was published in '' Muelleria''. The type specimen was collected on a hill in the south-eastern suburbs of

Hobart Hobart ( ; Nuennonne/Palawa kani: ''nipaluna'') is the capital and most populous city of the Australian island state of Tasmania. Home to almost half of all Tasmanians, it is the least-populated Australian state capital city, and second-small ...

. 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 ...

(atrata) is a Latin word meaning "dressed in black" referring to the black on the outside of the flower.

Distribution and habitat

Dark caladenia is only known from southern areas of Tasmania where it grows on

skeletal A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

soils in stunted forest on hillsides.

References

{{Taxonbar, from=Q15287446 atrata Plants described in 1994 Endemic orchids of Australia Orchids of Tasmania Taxa named by David L. Jones (botanist)