''Pterostylis alata'', commonly known as the striped greenhood, 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 ...

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 ...

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

. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has a white flower with prominent dark green stripes and a sharply pointed, brown-tipped

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 b ...

. Similar greenhoods growing on the Australian mainland were formerly known as ''Pterostylis alata'' but are now given the name ''

Pterostylis striata ''Pterostylis striata'', commonly known as the mainland striped greenhood, is a species of orchid endemic to south-eastern mainland Australia. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flo ...

''.

Description

''Pterostylis alata'' 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 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, aft ...

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 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 ...

and when not flowering, a rosette of dark green, wrinkled leaves, long and wide. Flowering plants have a single flower long and wide borne on a spike high. The flowers are white with dark green stripes. The dorsal sepal 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 are fused, forming a hood or "galea" 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 dorsal sepal curves forward with a narrow point long and is brownish near the tip. 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 cons ...

sepals are held closely against the galea, have erect, thread-like tips long and a broad V-shaped

sinus Sinus may refer to: Anatomy * Sinus (anatomy), a sac or cavity in any organ or tissue ** Paranasal sinuses, air cavities in the cranial bones, especially those near the nose, including: *** Maxillary sinus, is the largest of the paranasal sinuses, ...

between their bases. The labellum is long, about wide, brown and curved and protrudes above the sinus. Flowering occurs from May to August but mainly in June and July.

Taxonomy and naming

The striped greenhood was first formally described in 1806 by

Jacques Labillardière Jacques-Julien Houtou de Labillardière (28 October 1755 – 8 January 1834) was a French biologist noted for his descriptions of the flora of Australia. Labillardière was a member of a voyage in search of the Jean-François de Galaup, comte ...

who gave it the name ''Disperis alata''. (''

Disperis ''Disperis'' is a genus of plants in the orchid family, Orchidaceae. It has about 78 species.Mark W. Chase, Kenneth M. Cameron, John V. Freudenstein, Alec M. Pridgeon, Gerardo A. Salazar, Cássio van den Berg, and André Schuiteman. 2015. "An upd ...

'' is a genus of orchid mainly from

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

.) Labillardière published the description in ''

Novae Hollandiae Plantarum Specimen ''Novae Hollandiae Plantarum Specimen'' is a two-volume work describing the flora of Australia. Facsimiles of the originals can be found in the onlinBiodiversity Heritage Library (Vol.1)anVol 2) The author was the French botanist Jacques Labillar ...

'' from a plant he collected "in Van-Diemen's Land". In 1871 Heinrich Reichenbach changed the name to ''Pterostylis alata''. 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 ...

(''alata'') 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 of the ...

word meaning "winged".

Distribution and habitat

''Pterostylis alata'' grows in open forest and coastal scrub in Tasmania. ''Pterostylis alata'' does not grow on the mainland of Australia and plants formerly placed in this species are now recognised as ''

''.

References

{{Taxonbar, from=Q15492075 alata Endemic orchids of Australia Orchids of Tasmania Plants described in 1806