''Hakea petiolaris'', commonly known as the sea-urchin hakea, is a shrub or small tree with cream-coloured and pink or purple flowers and woody fruit. It 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 elsew ...

to the

south west The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each sepa ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, occurring at the coastal plain, jarrah forest and wheatbelt regions, often at the ancient

granite outcrops of Western Australia Granite outcrops of Western Australia are weathered landforms that occur throughout the state of Western Australia, composed primarily of the rock type granite. All recognised types of this landform can be observed, commonly as bornhardts, but a ...

Description

''Hakea petiolaris'' grows as an erect shrub or tree up to in height. The leaves have a distinctive pale-grey colour and are long and wide. The flowers are arranged in groups that appear on small branches or in the forks of branches. The groups are roughly spherical and contain 120 to 200 individual flowers. Each flower is long and white or cream in colour with the

perianth The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals) or tepals when ...

, (the non-reproductive part of the flower) ranging in colour from pink to purple. Flowering is followed by woody seed capsules which are long and wide. Each capsule splits into valves and releases 2 dark brown or black winged seeds.

Taxonomy

''Hakea petiolaris'' was first described by Carl Meissner in 1845, using a collection made at

York York is a cathedral city with Roman origins, sited at the confluence of the rivers Ouse and Foss in North Yorkshire, England. It is the historic county town of Yorkshire. The city has many historic buildings and other structures, such as a ...

by Ludwig Preiss. 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 ...

(''petiolaris'') is derived from the

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 ''petiolus'' meaning "small, slender stalk". The Latin epithet ''petiolaris'' refers to the leaves presentation on conspicuous stalks. There are three subspecies, differing in the sizes of their leaves and the colour of the perianth as it ages. * ''Hakea petiolaris'' Meisn. subsp. ''petiolaris'' has flowers that darken to mauve and then pink and has smaller leaves than those of the other subspecies. It is a shrub or small tree, one to two metres high, possesses a lignotuber and flowers in June. * ''Hakea petiolaris'' subsp. ''trichophylla'' Haegi flowers darken to mauve and then maroon. It is a large shrub or tree, greater than three metres in height and sometimes attaining nine metres. It releases seed stored in its capsules rather than regenerating from a lignotuber in response to fire and flowers from April to June. The hairs on the leaves, that shine grey-green during flowering, are persistent; this is referred to in the epithet ''trichophylla'', that is derived, according to Haegi from the Greek (,Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. Revised and augmented throughout by Sir Henry Stuart Jones with the assistance of Roderick McKenzie.''Oxford: Clarendon Press.

gen. The Book of Genesis (from Greek language, Greek ; Hebrew language, Hebrew: בְּרֵאשִׁית ''Bəreʾšīt'', "In hebeginning") is the first book of the Hebrew Bible and the Christian Old Testament. Its Hebrew name is the same as its i ...

; 'hair') and (; 'leaf'). * ''Hakea petiolaris'' subsp. ''angusta'' Haegi which has flowers that darken to mauve and then pinkish mauve. A shrub or small tree, 1–2 m high, it flowers from March to May. The epithet ''angusta'' is a Latin word meaning "narrow".

Distribution and habitat

* Subspecies ''petiolaris'' grows in

jarrah ''Eucalyptus marginata'', commonly known as jarrah, djarraly in Noongar language and historically as Swan River mahogany, is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is a tree with roug ...

forest, usually near

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

outcrops between the

Darling Range The Darling Scarp, also referred to as the Darling Range or Darling Ranges, is a low escarpment running north–south to the east of the Swan Coastal Plain and Perth, Western Australia. The escarpment extends generally north of Bindoon, to th ...

and

in the Avon Wheatbelt,

Jarrah Forest Jarrah forest is tall open forest in which the dominant overstory tree is ''Eucalyptus marginata'' (jarrah). The ecosystem occurs only in the Southwest Botanical Province of Western Australia. It is most common in the biogeographic region named in ...

and

Swan Coastal Plain The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geol ...

biogeographic region An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...

s. * Subspecies ''trichophylla'' grows near granite outcrops in shrubland near

Wongan Hills Wongan Hills is a range of low flat-topped hills in the Avon Wheatbelt bioregion of Western Australia. It is located at , in the Shire of Wongan–Ballidu. History The range was first recorded in 1836 by Surveyor General of Western Australia Jo ...

and with disjunct populations near

Kununoppin Kununoppin is a small town in the Wheatbelt region of Western Australia. The town is located on the Nungarin–Wyalkatchem Road and in the Shire of Trayning local government area, north east of the state capital, Perth, Western Australia. ...

and Tuttanning Nature Reserve east of Pingelly in the Avon Wheatbelt, Jarrah Forest and Mallee biogeographic regions. * Subspecies ''angusta'' is only known from a few small populations growing around granite outcrops near

Pingaring Pingaring is a small town in the Wheatbelt region of Western Australia. The name of the town is the Indigenous Australian name of a nearby spring that was first recorded by surveyors in 1926. The town originated as a railway siding on the Hy ...

in the Mallee biogeographic region.

Conservation

All three subspecies of ''H. petiolaris'' are listed as "not threatened" by the Western Australian Government

Department of Parks and Wildlife The Department of Parks and Wildlife (DPaW) was the department of the Government of Western Australia responsible for managing lands described in the ''Conservation and Land Management Act 1984'' and implementing the state's conservation and e ...

Cultivation

Hakea_Petiolaris_flowers_with_bees_April_2015

The species is propagated from seed, establishing itself as a large shrub, or a tree to around ten metres, the width is around two metres. The horticultural applications include use as a screening plant or hedge, or displayed as individual specimens. It is a fast growing and hardy species, frost resistant, bird attracting and has good potential as a feature plant. ''Hakea petiolaris'' is recommended for the attractive appearance of its flowers and attraction for birds. Clusters of dullish red flowers, contrasted by white styles, are presented at the leaf axis in the austral autumn or winter. The plant is successfully grown in the urbanised sub-coastal regions of southern Australia. The most common subspecies in cultivation is ''H. petiolaris'' subsp. ''trichophylla''.

Ecology

The presentation of flowers at the stem (

cauliflory Cauliflory is a botanical term referring to plants that flower and fruit from their main stems or woody trunks, rather than from new growth and shoots. This can allow trees to be pollinated or have their seeds dispersed by animals that climb o ...

) may be a relictual characteristic of a time when tall forest dominated the region and pollinators such as birds moved within the dense leaf canopy of under-storey species.