''Pterostylis rubenachii'', commonly known as the Arthur River greenhood, is a plant in the orchid family

Orchidaceae 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 ...

and 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 else ...

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. Both flowering and non-flowering plants have a rosette of leaves lying flat on the ground and flowering plants have up to seven crowded, transparent green flowers with darker green stripes.

Description

''Pterostylis rubenachii'', is a terrestrial,

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 wid ...

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, ...

, herb with an underground tuber. It has a rosette of between four and six, elliptic to egg-shaped leaves, each leaf long and wide, lying flat on the ground. Between two and seven transparent green flowers with darker green stripes are crowded together on a flowering spike high with two or three stem leaves with their bases wrapped around it. The flowers are long and about 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 c ...

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 coine ...

and petals are joined to form a hood called the "galea" over the column. The dorsal sepal is gently curved but suddenly curves downward near the tip and is about the same length as the petals. The lateral sepals turn downwards and are about long, wide and fused together forming a cup with tips about long. The labellum is about long, wide and whitish-green with a dark green, appendage. Flowering occurs in October and November.

Taxonomy and naming

''Pterostylis rubenachii'' was first formally described in 1998 by David Jones from a specimen collected in 1837 and the description was published in ''Australian Orchid Research''. The specific epithet (''rubenachii'') honours Les Rubenach who is one of the few people to have found this species.

Distribution and habitat

The Arthur River greenhood grows in moist heath at altitudes of in the Arthur River area.

Conservation

''Pterostylis rubenachii'' is listed as "endangered" under the Australian Government ''

Environment Protection and Biodiversity Conservation Act 1999 The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cult ...

'' and the Tasmanian Government ''

Threatened Species Protection Act 1995 The ''Threatened Species Protection Act 1995'' (TSP Act), is an act of the Parliament of Tasmania that provides the statute relating to conservation of flora and fauna. Its long title is An Act to provide for the protection and management of t ...

''. Only about 800 plants of this species survive, mostly in the Arthur-Pieman Conservation Area. It is threatened by weed invasion, cattle grazing and off-road vehicles.

References

{{Taxonbar, from=Q15492226 rubenachii Endemic orchids of Australia Orchids of Tasmania Plants described in 1998