Synonymy

Hakea megadenia R.M.Barker, in M.R.Banks et al. (eds), Aspects of Tasmanian Botany: a Tribute to Winifred Curtis 83 (1991)

T: scenic lookout on road to Swansea, Tas., 17th May 1976, J.Armstrong 867 & J.Powell; holo: HO; iso: NSW.

[Hakea rostrata auct. non F.Muell. ex Meisn.: W.Curtis, Students Fl. Tasmania 3: 609 (1967), p.p.]

[Hakea rugosa auct. non R.Br.: W.Curtis, Students Fl. Tasmania 3: 609 (1967), p.p.]

Description

Upright unisexual shrub or small tree, to 5 m tall. Branchlets densely appressed-pubescent, with ferruginous and sometimes white hairs, persistent until flowering. Leaves terete or flattened, 3.5–13.5 cm long, 1–7 mm wide, shiny with white hairs when young, ferruginous at very base, glabrescent.

Inflorescence on male plants with 3–14 flowers, on female plants with 1–8 flowers; involucre 1.5–2 mm long; rachis 1–3 mm long, ferruginous-hairy; pedicels 2–5 mm long, with hairs white appressed-sericeous, extending onto perianth. Perianth 3–5 mm long, white or cream-white internally. Pistil curved, 5–8 mm long; pollen presenter an oblique disc, 0.8–1 mm long; gland a slightly curved rectangular flap, 0.7–1 mm high in female flowers, 0.5–0.8 mm high in male flowers.

Fruit sigmoidal, 1.8–2.5 cm long; 0.9–1.2 cm wide. Seed 10.5-13.5 mm long; wing partly down one side of seed body only.

Distribution and ecology

Confined to the east coast of Tas. and the Furneaux Group in the eastern Bass Strait. Found in river scrub or dry open forest, at low altitude and coastal on the mainland but at higher altitudes on the islands.

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 Feb.–July.

Derivation of name

From mega-, Greek for large and adenos, Greek for gland - a reference to the long gland in this species when compared with its close relative H. epiglottis.

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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.

The Rostrata group all share the characteristics of pubescent pedicel and perianth, oblique pollen presenter and woody, sigmoid fruits which are retained on the bushes.

Members of the group are H. cyclocarpa, H. epiglottis, H. megadenia, H. rostrata and H. rugosa .

Notes

No evidence has been found at this stage to indicate that bisexual populations occur within this species as they do in H. epiglottis. Island populations of this species appear to be more robust than those on the mainland; they usually have longer leaves, slightly longer perianths and slightly larger fruit.

Hakea megadenia and H. epiglottis can be separated on a number of characters which are not immediately obvious. The young growth is sufficiently different to distinguish between the species. H. medadenia has branchlets in which the hairs are all ferruginous, sometimes mixed with some white hairs; the ferruginous hairs extend on to the very base of the leaves, but the rest of the young leaf is covered with white appressed hairs giving the leaf a very pale appearance in contrast to the branchlet. On the other hand in H. epiglottis the branchlet is usually white in appearance while the leaves are covered with appressed ferruginous hairs. Thus ferruginous young leaves are characteristic of H. epiglottis while such leaves never occur in H. megadenia.

Other differences between the species include the colour of the rachis hairs, ferruginous in H. megadenia, but usually white in H. epiglottis, the different flowering times and the curvature of the bud; in H. epiglottis the limb in bud is recurved and pressed against the claw while in H. megadenia the recurvature is insufficient for the limb to meet the claw. Flattened leaves occasionally occur in populations of H. megadenia and it would appear that the juvenile leaves of this species are flattened (observed Wittunga Botanic Gardens). W.R.Barker observed that where the two species occurred together naturally on the Tasman Peninsula, H. epiglottis was usually found in low lying areas while H. megadenia was found in non swampy areas.

Representative specimens

Tas.: Apsley R., M.J.Brown 193 (HO); 1 km SW of Cherry Tree Hill, A.M.Buchanan 3605 (HO); Survey Hill, Flinders Is., H.Lee 114 (MEL); Cape Barren Is., J.S.Whinray 43 (MEL); halfway up Strzelecki Peak, Flinders Is., 10 Apr. 1954, J.H.Willis s.n. (MEL).

Weblinks

A photograph of this species can be seen on the Australian National Botanic Gardens site.

There are images of H. megadenia showing the large gland characteristic of this species, in the Key to Tasmanian Plants pages.

Further illustrations

I. Holliday, Hakeas. A Field and Garden Guide 122-3 (2005)

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