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Eucalyptus argyphea


Silver mallet

Eucalyptus argyphea L.A.S. Johnson & K.D. Hill, Telopea 4: 603 (1992).

T: Western Australia: 12km W of Harrismith on road to Wickepin (32
°55'S, 117°44'E), 8 Nov. 1983, K.D.Hill 659, L.A.S.Johnson, D.F.Blaxell, M.I.H.Brooker & S.D.Hopper; holo: NSW; iso: CANB, PERTH.

Mallet to 15 m tall. Lignotuber absent.
Bark smooth throughout, mottled silvery grey and pale pink-grey.
Branchlets lacking oil glands in the pith.
Juvenile growth (coppice or field seedlings to 50 cm): not seen.
Adult leaves alternate, petioles 1-2.5 cm long; blade lanceolate or sometimes falcate, (6)7-13 cm long, 0.8-2(2.2) cm wide, base tapering to petiole, margin entire, apex acute, concolorous, glossy, dark green, side veins acute, reticulation dense, intramarginal vein very close to margin, oil glands intersectional, numerous, irregular.
Inflorescences axillary unbranched, pendulous, peduncles 1-2.5 cm long; buds 7 or 9, pedicellate, elongated-ovoid with shallow longitudinal ribs on hypanthium only, scar present, operculum narrowly conical and sometimes slightly narrower than hypanthium at the join, stamens all inflexed or mostly inflexed with a few irregularly flexed, anthers cuboid, versatile, dorsifixed, dehiscing by longitudinal slits, style long and straight, stigma blunt to rounded, locules 3(4), the placentae each with 4 vertical rows of ovules; flowers creamy white.
Fruit down-turned, pedicellate, flattened-globose, smooth or scarcely ribbed, 0.7-1 cm wide (including any ribs), disc descending vertically, valves 3(4), prominently exserted and fragile.
Seed brown to grey-brown, 1-2.5 mm long, ovoid or flattened-ovoid, dorsal surface very shallowly reticulate and often with two longitudinal furrows, hilum ventral.

Cultivated seedling (measured at ca node 10): cotyledons Y-shaped (bisected); stems squared in cross-section; leaves always at least shortly petiolate, linear to narrowly elliptical or narrowly lanceolate until ca node 10 then becoming broadly elliptical to ovate by node 15, still opposite at nodes 10 to 15 (or sometimes becoming alternate for one or two nodes then reverting to opposite), 1-3 cm long, 0.2-2 cm wide, green, dull.


NOTES

Eucalyptus argyphea (Greek, argypheos, silvery white, referring to the bark).

A mallet endemic to Western Australia, found in the southern wheatbelt with the main distribution from east of Wickepin to east of Lake King and south towards Jerramungup. The bark is smooth, grey to silvery and adult leaves glossy green.

Eucalyptus argyphea belongs in Eucalyptus subgenus Symphyomyrtus section Bisectae subsection Destitutae because buds have two opercula, cotyledons are Y-shaped and branchlets lack oil glands in the pith. Within this sub-subsection E. argyphea belongs to a group of eight species and two subspecies characterized by usually pendulous inflorescences with pedicellate ovoid buds with a conical to beaked operculum, flattened-globose fruits with exserted fragile valves and adult leaves that are green, densely reticulate and have numerous intersectional oil glands. The species are E. argyphea, E. recta , E. falcata , E. ornata , E. petrensis , E. goniantha (with two subspecies), E. kessellii and E. balanopelex , which together form sub-series Rugatae.

Eucalyptus argyphea, E. ornata and E. recta are mallets. They differ only in the size and degree of ribbing of the buds and fruits. E. ornata from around Kondinin in the southern wheatbelt is heavily ribbed, whilst E. recta , found only near Cadoux in the central wheatbelt, has scarcely ribbed buds slightly larger than the other two species and smooth fruit. The shallowly ribbed buds and almost smooth fruit of E. argyphea are of similar size to those of E. ornata . E. falcata , widespread in wheatbelt and sub-coastal areas, differs in being a mallee. The remaining species in sub-series Rugatae are coastal mallees.