 Habit. Subspecies indeterminable. Photo © I.Holliday |
 Subspecies indeterminable. Photo © I.Holliday |
 Leaves and inflorescence. Photo © W.R.Barker |
 Inflorescence. Photo © W.R.Barker |
 Persistent unopened fruits. Photo © W.R.Barker |
Synonymy
Hakea obliqua R.Br., Trans. Linn. Soc. London 10: 180 (1810) subsp. obliqua
T: Hort. Kew, 1809, R.Brown Iter Austral. 7; syn: BM; South Coast, Bay I, [Lucky Bay, Western Australia], 1802, R.Brown Iter Austral. 12; syn: BM.
Hakea brookeana F.Muell., Australas. J. Pharm. 1(11): 430 (1886). T: Israelite Bay, 'At or towards Mt Ragged', Western Australia, without date, Miss S. Brooke s.n.; syn: MEL 108085.
Hakea obliqua var. brooksiana W.E.Blackall & B.J.Grieve, How to Know W. Australian Wildfl. 2nd edn, 1: 116 (1974), nom. inval.? (basionym not cited).
Description
Erect dense shrub, 1–2 m tall, ?lignotuberous. Branchlets and young leaves ferruginous. Leaves terete, 1–7 cm long, 1.1–2.5 mm wide, not grooved; mucro erect.
Inflorescence with 2–8 flowers; involucre 3.5–5 mm long; pedicels 3.5–6 mm long, appressed-sericeous, with hairs white, extending onto perianth. Perianth 5.5–7.5 mm long. Pistil 6.5–10 mm long; disc of pollen presenter 0.8–1 mm long; gland 1.2–1.5 mm long.
Fruit erect, obliquely broadly ovate or obovate, 3–4.5 cm long, 2.1–3.5 cm wide, with large stout corky projections when mature; beak smooth; apiculum straight or curved, 1–6 mm long. Seed 23–28 mm long, occupying part of valve; wing encircling seed body.
Distribution and ecology
Occurs on the south coastal plain between Stirling Ra. and Israelite Bay, Western Australia, inland as far as Pingrup; grows in sand plain heaths.
To plot an up to date distribution map based on herbarium collections for this species see Australia's Virtual Herbarium. Localities outside the native range may represent cultivated or naturalised records.
Flowering time
Flowers Sept.–Oct.
Derivation of name
From obliquus, Latin for oblique, and presumably a reference to the angle of the leaves to the stem.
How the infraspecific taxa differ
As the name suggests, the flowers of ssp. parviflora are smaller than those of ssp. obliqua. This is reflected in all of the floral measurements (see below). The fruits of ssp. obliqua appear to become much more corky with age as well as being mostly longer and wider, but more observations are needed here since there were few mature fruits of ssp. parviflora seen.
There is also a tendency for ssp. parviflora to have longer leaves which are apparently more curved than in ssp. obliqua; this tendency is best shown in the comparative leaf widths which are much less in ssp. parviflora.
Ssp. parviflora occurs in more north-westerly localities than subsp. obliqua, being distributed in the sand heaths from Coorow through to the Fitzgerald NP while ssp. obliqua is found in the sand heaths between the Stirling Ranges and Israelite Bay.
| | ssp. obliqua | ssp. parviflora |
| Leaf width, mm | 1.1-2.5 | 1.2-1.5 |
| Involucral bud length, mm | 3.5-5 | 2-3 |
| Pedicel length, mm | 3.5-6 | 1.5-2.5 |
| Perianth length, mm | 5.5-7.5 | 4.5-5.5 |
| Pistil length. mm | 6.5-10 | 5.5-6.5 |
| Gland height, mm | 1.2-1.5 | 0.5-0.7 |
| Fruit length, cm | 3-4.5 | (1.7-)2.7-3.5 |
| Fruit width, cm | 2.1-3.5 | 1.3 |
Relationships
Part of Section Hakea of Bentham (as Euhakea) and characterised by a non-conical pollen presenter, leaves without obvious venation, perianths with or without hairs and fruits with or without horns. Barker et al. (1999) recognised a number of informal morphological groups within the section.
Within this section 5 species were assigned to the informal Obliqua group by Barker et al. (1999). The group is close to the Ceratophylla group, sharing the morphological characteristics of few-flowered inflorescences with pubescent flowers on an obscure rachis, oblique pollen presenters and distinctly woody fruits without horns and usually without beaks and seed in which the wing encircles the seed body; the groups differ in the terete leaves of this group compared with the flat leaves of the Ceratophylla group.
Members of the group are H. adnata, H. brachyptera, H. obliqua, H. polyanthema and H. psilorrhyncha, all from southern WA.
Notes
Previously considered to have a much wider distribution but populations from heaths north of Perth are now treated as H. psilorrhyncha. Not only does it differ in its more northerly distribution, its more slender open habit, longer pedicel, perianth, pistil and anthers and its distinctive pollen presenter (see image above) but it may also differ in its red styles as opposed to cream or green styles of H. obliqua, but further observations are needed.
Fruit from more easterly locations in the distributional range of subsp. obliqua show a more marked corkiness in contrast to collections from westerly locations. This characteristic is also exhibited by fruit of H. pandanicarpa. Specimens from Esperance are noticeably much more corky than those from Ravensthorpe, and this led to Mueller describing H. brookeana. There is no other character to support recognition of this taxon.
The correct spelling of the name of collector of the type material of H. brookeana was apparently Brooks and thus the species should have been named brooksiana. Mueller changed the spelling to brooksiana in his second Systematic Census of Australian Plants (1889), but the original spelling stands according to the international rules governing botanical names. However the species is not recognised here and has been reduced to a synonym of H. obliqua ssp. obliqua.
Representative specimens
Western Australia: Truslove, between Salmon Gums and Esperance, W.E.Blackall 1034 (PERTH); between Pingrup and Lake Grace, W.E.Blackall 3056 (PERTH); Bremer Bay Rd, 3.2 km W of Bremer Bay, R.Filson 9110 (MEL); c. 55 km E of Condingup on Fisheries Rd, D.B.Foreman 1319 (MEL); Cape Le Grand National Park, by Rossiter Bay, A.Strid 21232 (PERTH).
Weblinks
Link to FloraBase treatment of this species for WA.
For further information and images of this species in the Esperance region of Western Australia see William Archer’s Hakea page in Esperance Wildflowers
A photograph of this species can be seen on the Australian National Botanic Gardens site.
Further illustrations
I. Holliday, Hakeas. A Field and Garden Guide 146-7 (2005)
J.A..Young, Hakeas of Western Australia. A Field and Identification Guide 78 (2006)