''Bossiaea walkeri'', commonly known as cactus bossiaea, cactus pea, or Walker's stick bush, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

in the pea 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 southern mainland Australia. It is a rigid, much-branched shrub with flattened, winged cladodes and red, pea-like flowers between July and November in the species' native range.

Description

''Bossiaea walkeri'' is a rigid, much-branched shrub that grows up to high and wide and is more or less

glabrous Glabrousness () is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, ...

. The stems and branches are flattened and winged, ending in cladodes wide. The leaves, when present, are reduced to scales about long, occasionally more or less round and up to long near the base or on young plants. The flowers are long and are borne singly at nodes on the cladodes on a pendent

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 ...

up to long with overlapping, broadly egg-shaped

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s up to long at the base. There are egg-shaped bracteoles long on the pedicel, but that fall off as the flower opens. The five

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 about long and joined at the base, forming a tube long, the two upper lobes long and much longer than the lower three. 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 is usually red, long and shorter than 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 ...

and

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 ...

that are each about long. The wings are salmon pink and the keel is deep red. Flowering occurs between July and November and the fruit is an oblong pod about long.

Taxonomy

''Bossiaea walkeri'' was first formally described in 1861 by

Ferdinand von Mueller Baron Sir Ferdinand Jacob Heinrich von Mueller, (; 30 June 1825 – 10 October 1896) was a German-Australian physician, geographer, and most notably, a botanist. He was appointed government botanist for the then colony of Victoria, Australia ...

in ''

Fragmenta Phytographiae Australiae ''Fragmenta phytographiae Australiae'' is a series of papers written by the Victorian Government botanist Ferdinand von Mueller in which he published many of his approximately 2000 descriptions of new taxa of Australian plants. Including the p ...

'' from specimens collected by Alexander Walker on hills between the Lachlan and

Murrumbidgee River The Murrumbidgee River () is a major tributary of the Murray River within the Murray–Darling basin and the second longest river in Australia. It flows through the Australian state of New South Wales and the Australian Capital Territory, desce ...

s. 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 ...

(''walkeri'') honours the collector of the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

specimens.

Distribution and habitat

Cactus bossiaea grows in mallee, low open woodland, creek beds and rocky outcrops and occurs in Western Australia, South Australia, Victoria and New South Wales. It is found from near

Shark Bay Shark Bay () is a World Heritage Site in the Gascoyne region of Western Australia. The area is located approximately north of Perth, on the westernmost point of the Australian continent. UNESCO's listing of Shark Bay as a World Heritage S ...

in Western Australia, through the south-west of the state to southern South Australia, the

Murray River The Murray River (in South Australia: River Murray; Ngarrindjeri language, Ngarrindjeri: ''Millewa'', Yorta Yorta language, Yorta Yorta: ''Dhungala'' or ''Tongala'') is a river in Southeastern Australia. It is List of rivers of Australia, Aust ...

and

Wyperfeld National Park The Wyperfeld National Park is the third-largest national park in Victoria, Australia, located in the Mallee district, approximately north-west of Melbourne. The national park was declared in 1921 and has been expanded significantly since, to ...

in Victoria, and to inland New South Wales. The species is rare in Victoria, where it is listed as "endangered" under the Victorian Government ''

Flora and Fauna Guarantee Act 1988 The ''Flora and Fauna Guarantee Act 1988'', also known as the ''FFG Act'', is an act of the Victorian Parliament designed to protect species, genetic material and habitats, to prevent extinction and allow maximum genetic diversity within the Au ...

''.

Ecology

The pendent flowers and the unusual shape of the flower parts of ''B. walkeri'' suggest that it is bird-pollinated. Honeyeaters and blue wrens have been observed visiting the flowers.

Reproduction

The 2cm flowers are produced between July and November. They will often flower after seed has set to take full advantage of additional rainfall after a dry period. The fruit is a hairless, flattened 6cm by 1cm pod that contains brown seeds. The pods begin green but mature to brown, the seeds become ripe usually 2 to 3 months after flowering has finished. Then on a hot day the pods will explode to disperse the seed several metres. Birds are the primary pollinators, but small animals and insects also contribute.

Uses

Use in horticulture

This species is described as "decorative" and can be propagated from seed or from cuttings. It can be grown in full sun or part shade, is drought and frost tolerant but needs relatively dry, well-drained soil.

Other uses

''Bossiaea walkeri'' produces a very distinct honey, although it appears to have no pastoral value.

References

{{Taxonbar, from=Q10740874 walkeri Flora of New South Wales Flora of Victoria (state) Rosids of Western Australia Flora of South Australia Taxa named by Ferdinand von Mueller