''Swainsona pterostylis'' is a species of flowering plant in the family

Fabaceae Fabaceae () or Leguminosae,International Code of Nomen ...

and is

endemic Endemism is the state of a species being found only 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 foun ...

to northern parts of Western Australia. It is a low-growing or prostrate

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

herb, with

imparipinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

leaves with mostly 11 to 19 broadly elliptic leaflets, and

raceme A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are ...

s of 5 to more than 30 purple or violet flowers.

Description

''Swainsona pterostylis'' is low-growing or prostrate perennial

herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...

, that typically grows to a height of up to about high, and usually has 3 hairy stems. Its leaves are imparipinnate, mostly long on a

petiole Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, and ...

, with mostly 11 to 19, broadly elliptic to narrowly egg-shaped with the narrower end towards the base, the side leaflets long and wide. There is a

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole (botany), petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part ...

long at the base of the petiole. The flowers are arranged in racemes long with 5 to more than 30 flowers on a peduncle about wide, each flower long on a

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

long. The

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 Etymology The term ''sepalum'' ...

s are joined at the base, forming a tube about long, the sepal lobes equal to or about as long as the tube. The petals are purple to violet, the

standard Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object ...

petal about long and wide, the

wings A wing is a type of fin that produces both lift and drag while moving through air. Wings are defined by two shape characteristics, an airfoil section and a planform. Wing efficiency is expressed as lift-to-drag ratio, which compares the bene ...

long, and the

keel The keel is the bottom-most longitudinal structural element of a watercraft, important for stability. On some sailboats, it may have a fluid dynamics, hydrodynamic and counterbalancing purpose as well. The keel laying, laying of the keel is often ...

about long and deep. Flowering occurs from April to October, and the fruit is oblong to almost spherical, long and wide.

Taxonomy and naming

This species was first formally described in 1825 by

Augustin Pyramus de Candolle Augustin Pyramus (or Pyrame) de Candolle (, , ; 4 February 17789 September 1841) was a Swiss people, Swiss botany, botanist. René Louiche Desfontaines launched de Candolle's botanical career by recommending him at a herbarium. Within a couple ...

who gave it the name ''Astragalus pterostylis'' in his '' Prodromus Systematis Naturalis Regni Vegetabilis''. In 1967, Reinier van den Brink transferred the species to ''

Swainsona ''Swainsona'' is a genus of about 85 species of flowering plants in the family Fabaceae, and is endemic to Australia. Plants in this genus are herbs or subshrubs with imparipinnate leaves and usually purple flowers similar to others in t ...

'' as ''S. pterostylis''. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

(''pterostylis'') means "having a

style Style, or styles may refer to: Film and television * ''Style'' (2001 film), a Hindi film starring Sharman Joshi, Riya Sen, Sahil Khan and Shilpi Mudgal * ''Style'' (2002 film), a Tamil drama film * ''Style'' (2004 film), a Burmese film * '' ...

Distribution and habitat

''Swainsona pterostylis'' grows on coastal sandhills and red claypans, often in limy or salty soils in the

Avon Wheatbelt The Avon Wheatbelt is a bioregion in Western Australia. It has an area of . It is considered part of the larger Southwest Australia savanna ecoregion. Geography The Avon Wheatbelt bioregion is mostly a gently undulating landscape with low rel ...

, Carnarvon,

Dampierland Dampierland is an interim Australian bioregion in Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territo ...

Gascoyne The Gascoyne region is one of the nine regions of Western Australia. It is located in the northwest of Western Australia, and consists of the local government areas of Carnarvon, Exmouth, Shark Bay and Upper Gascoyne. The Gascoyne has about of ...

Geraldton Sandplains Geraldton Sandplains is an Interim Biogeographic Regionalisation for Australia, interim Australian bioregion of Western Australia. It has an area of . The Geraldton Sandplains is part of the larger Southwest Australia savanna ecoregion, as asses ...

Great Sandy Desert The Great Sandy Desert is an interim Australian bioregion,IBRA Version 6.1
data

, Murchison,

Pilbara The Pilbara () is a large, dry, sparsely populated regions of Western Australia, region in the north of Western Australia. It is known for its Indigenous Australians, Aboriginal people; wealth disparity; its ancient landscapes; the prevailing r ...

and Yalgoo bioregions of northern Western Australia.

References

{{Taxonbar, from1=Q15483570, from2=Q50827290

pterostylis ''Pterostylis'' is a genus of about 300 species of plants in the orchid family, Orchidaceae. Commonly called greenhood orchids, they are terrestrial, deciduous, perennial, tuberous, herbs found in Australia, New Zealand, New Guinea, New Caled ...

Fabales of Australia Flora of Western Australia Taxa named by Augustin Pyramus de Candolle Plants described in 1825