''Corybas expansus'', commonly known as the flared helmet orchid or dune helmet orchid is a species of terrestrial

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 els ...

to South Australia. It has a heart-shaped to more or less round leaf and a single purplish flower with greenish or transparent areas.

Description

''Corybas expansus'' is a

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

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, a ...

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 medicina ...

which forms small colonies. It has a broad heart-shaped or almost round leaf long and wide. The leaf is bright green on the upper surface and silvery green on the lower side. The single flower is erect, reddish purple with greenish or translucent areas, long and wide. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

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 ...

is mostly transparent green, long and wide. It is erect near its base then curves forward, partly covering the labellum. The

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

sepals are linear but tapered, long, wide and joined to each other at the base. The

petal Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usuall ...

s are lance-shaped, about long, wide and curved. The labellum is longer than the dorsal sepal and forms a tube about long near its base, before curving and flattening into a concave dish shape, long and wide. The upper part of the labellum is reddish purple grading to white from the centre down. There are teeth or serrations up to long around the edges of the labellum. Flowering occurs in July and August.

Taxonomy

''Corybas expansus'' was first formally described in 1991 by David Jones from a specimen collected in the

Warrenben Conservation Park Warrenben Conservation Park (formerly Warrenben National Park) is a protected area located in the Australian state of South Australia on the Yorke Peninsula of about north-east of Marion Bay. The conservation park consists of land in section ...

and the description was published in ''Australian Orchid Research''. 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 ...

(''expansus'') 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 ...

word meaning "spread out", referring to the flared labellum. In 2002, David Jones and Mark Clements proposed splitting ''Corybas'' into smaller genera and placing this species into ''Corysanthes'' but the change has not been widely accepted.

Distribution and habitat

The flared helmet orchid grows on the lee side of dunes in the shelter of trees (especially ''

Eucalyptus diversifolia ''Eucalyptus diversifolia'', commonly known as the soap mallee, coastal white mallee, South Australian coastal mallee, or coast gum is a species of mallee that is endemic to an area along the southern coast of Australia. It has smooth bark, lan ...

'') and in sandy loam in sheltered places. It occurs in coastal areas on the southern tip of the

Eyre Eyre may refer to: Name *Eyre (given name) *Eyre (surname) Places Australia National *Eyre Highway, a highway connecting South Australia and Western Australia South Australia * Eyre Peninsula (disambiguation) *Eyre, South Australia, a suburb * ...

, Yorke and

Fleurieu Peninsula The Fleurieu Peninsula () is a peninsula in the Australian state of South Australia located south of the state capital of Adelaide. History Before British colonisation of South Australia, the western side of the peninsula was occupied by the ...

s and on

Kangaroo Island Kangaroo Island, also known as Karta Pintingga (literally 'Island of the Dead' in the language of the Kaurna people), is Australia's third-largest island, after Tasmania and Melville Island. It lies in the state of South Australia, southw ...

Conservation status

''Corybas expansus'' is classified as "vulnerable" under the South Australian ''

National Parks and Wildlife Act 1972 Protected areas of South Australia consists of protected areas located within South Australia and its immediate onshore waters and which are managed by South Australian Government agencies. As of March 2018, South Australia contains 359 separ ...

''. The main threats to the species are inappropriate fire regimes and weed invasion.

References

{{Taxonbar, from=Q10261030 expansus Endemic orchids of Australia Orchids of South Australia Plants described in 1991 Taxa named by David L. Jones (botanist)