Eucalyptus mannifera subsp. praecox

Brittle gum

Eucalyptus | Symphyomyrtus | Maidenaria | Triangulares | Microcarpae

Eucalyptus mannifera subsp. praecox (Maiden) L.A.S.Johnson, Contr. New South Wales Natl Herb. 3: 107 (1962).

Eucalyptus praecox Maiden, J. & Proc. Roy. Soc. New South Wales 48: 423 (1915). T: Capertee, NSW, Mar. 1901, J.H.Maiden & J.L.Boorman s.n.; holo: NSW; iso: BM.

Eucalyptus lactea R.T.Baker, Proc. Linn. Soc. New South Wales 25: 691 (1901). T: Ilford, NSW, before 1900, R.T.Baker NSW 54075; lecto: NSW, fide L.A.S.Johnson, loc. cit.

Tree to 10 m tall. Forming a lignotuber.
Bark smooth throughout or with some persistent rough, grey slabs at base of trunk; smooth bark usually powdery, white and grey; branchlets sometimes glaucous.
Juvenile growth (coppice or field seedlings to 50 cm): stem rounded in cross-section; juvenile leaves opposite, sessile or subsessile for many pairs, round to ovate or elliptical, 4.5–8.5 cm long, 4.5–6 cm wide, margin entire or crenulate, base lobed, apex usually rounded, blue-green to grey-green, often slightly glaucous.
Adult leaves alternate, petiole 0.8–2.5 cm long; blade lanceolate to falcate, 7–17.5 cm long, 1–3 cm wide, base tapering to petiole, margin entire, concolorous, slightly glossy or dull, green to grey-green, side-veins at an acute or wider angle to midrib, densely reticulate, intramarginal vein parallel to and remote from margin, oil glands mostly island.
Inflorescence axillary unbranched, peduncles 0.4–1 cm long, buds 7 per umbel, pedicels 0.2–0.4 cm long. Mature buds obovoid to ovoid, 0.5–0.6 cm long, ca 0.3 cm wide, green or glaucous, scar present, operculum conical to rounded, stamens irregularly flexed, anthers cuboid to oblong, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, stigma blunt, locules 3 or 4, the placentae each with 4 vertical ovule rows. Flowers white.
Fruit on pedicels 0.1–0.4 cm long, hemispherical or cup-shaped, 0.3–0.6 cm long, 0.5–0.7 cm wide, disc raised and convex to oblique, valves 3 or 4, exserted or near rim level.
Seeds brown or black, 1–2 mm long, ovoid or flattened-ovoid, often pointed at one end, lacunose, dorsal surface smooth or shallowly pitted, hilum ventral.

Cultivated seedlings (measured at ca node 10): cotyledons more or less oblong; stems rounded in cross-section, glaucous or non-glaucous; leaves sessile, opposite for more than 10 nodes, orbicular to ovate, 4.5–8.5 cm long, 4.5–6 cm wide, base amplexicaul, margin entire or crenulate, apex rounded, emarginate or pointed, glaucous or grey-green.

Flowering has been recorded in June and July (Blakely, 1934).

Eucalyptus mannifera is a widespread, small to medium-sized tree species of the Central and Southern Tablelands of New South Wales extending into the hills and slopes of eastern Victoria.

E. mannifera has predominantly or completely smooth, white bark that is powdery to touch and is easily recognised among gum-barked species by the form, bark, dull bluish green to green leaves and seven-budded inflorescences and small fruit. In places it co-occurs with another unrelated, smooth-barked white gum, E. racemosa subsp. rossii (a scribbly gum). On occasions E. racemosa subsp. rossii lacks insect scribbles on the bark and in these circumstances the two species can be superficially similar. E. mannifera has pale yellow newly exposed bark while E. rossii has brilliant yellow to orange new bark. E. mannifera has an operculum scar on the buds, lacking in E. racemosa subsp. rossii and the operculum is usually pointed in E. mannifera, rounded in E. racemosa subsp. rossii. Leaf reticulation in E. mannifera is moderate to dense whilst very sparse in E. racemosa subsp. rossii.

There are three subspecies:

E. mannifera subsp. mannifera
The most widespread and has linear to lanceolate juvenile leaves. Subsp. mannifera occurs from around Bathurst in mid-western New South Wales south into Victoria, east from the Snowy River to Mt Buffalo, Mt Baranduda and Paradise Falls, always on dryish, often stony sites.

E. mannifera subsp. praecox
Has rounded to ovate juvenile leaves and occurs north of Bathurst in the Liverpool Range Capertee area of New South Wales on dry sandy sites.

E. mannifera subsp. gullickii
Has elliptical to broadly lanceolate juvenile leaves and occurs usually adjacent to swampy sites in eastern New South Wales from the Blue Mountains and Megalong Valley, south to Pigeon House area.

Eucalyptus mannifera belongs in Eucalyptus subgenus Symphyomyrtus section Maidenaria, a large group of species more or less restricted to south-eastern Australia, characterised by bilobed cotyledons, simple axillary inflorescences, buds with two opercula, stamens with versatile anthers and flattened seeds with a ventral hilum. Within this section E. mannifera and three other species form series Microcarpae diagnosed by the smooth white bark, juvenile leaves that are shortly petiolate, non-swampy habitat, and small, rather flat-topped fruit. The other three species are E. scoparia (which differs in having glossy adult leaves), E. dorrigoensis (which has sessile stem-clasping ovate juvenile leaves) and E. elliptica (which has sessile large ovate-elliptic juvenile leaves).

Eucalyptus mannifera: Greek manna, gum and Latin -fera, bearing.

subsp. praecox: Latin praecox, precocious, occurring early, referring to the production of flowers whilst juvenile leaves are present.