''Diuris ostrina'', commonly known as Darling Scarp donkey 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 ...

that is

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 ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. It has two or three linear to lance-shaped leaves and up to five brown to brownish-yellow and purple-mauve flowers.

Description

''Diuris ostrina'' is a

tuber Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...

ous,

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 ...

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 two or three linear leaves long and wide. Up to five brown to brownish-yellow and purple-mauve flowers long and wide are borne on a flowering stem tall. The dorsal

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 ...

is egg-shaped, long and wide, the lateral sepals narrowly oblong, parallel or crossed, long and wide. 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 broadly elliptic, long and wide on a stalk long. The labellum is long with three lobes - the centre lobe broadly wedge-shaped, long and wide, the side lobes spread widely apart and egg-shaped to oblong, long and wide. There is a single smooth, yellow callus ridge long, along the mid-line of the labellum. Flowering occurs in October and November.

Taxonomy and naming

''Diuris ostrina'' was first formally described in 2016 by David Jones and Christopher J. French in ''Australian Orchid Review'', from a specimen collected in

Greenmount National Park Greenmount National Park is a national park in the locality of Greenmount, Western Australia, 22 km east of Perth. It is one of the smaller national parks along the Darling Scarp and is a component of the Darling Range Regional Park. Due t ...

in 1997. 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 ...

(''ostrina'') means "purple", referring to the main colour of the labellum of this species.

Distribution and habitat

Darling Scarp donkey orchid is restricted to the

Darling Scarp The Darling Scarp, also referred to as the Darling Range or Darling Ranges, is a low escarpment running north–south to the east of the Swan Coastal Plain and Perth, Western Australia. The escarpment extends generally north of Bindoon, to th ...

where it grows in shrubby forest and woodland in the

Jarrah Forest Jarrah forest is tall open forest in which the dominant overstory tree is ''Eucalyptus marginata'' (jarrah). The ecosystem occurs only in the Southwest Botanical Province of Western Australia. It is most common in the biogeographic region named in ...

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 ...

bioregions of south-western Western Australia.

Conservation

''Diuris ostrina'' is listed as "not threatened" by the Western Australian Government

Department of Biodiversity, Conservation and Attractions The Department of Biodiversity, Conservation and Attractions (DBCA) is the Western Australian government The Government of Western Australia, formally referred to as His Majesty's Government of Western Australia, is the Australian state de ...

References

{{Taxonbar, from=Q44247357 ostrina Endemic orchids of Australia Orchids of Western Australia Plants described in 2016 Taxa named by David L. Jones (botanist) Endemic flora of Western Australia