Eucalyptus conglobata subsp. conglobata

Port Lincoln mallee, Cong mallee

Eucalyptus | Symphyomyrtus | Dumaria | Rufispermae

Eucalyptus conglobata (R.Br. ex Benth.) Maiden, Crit. Revis. Eucalyptus 6: 273 (1922) subsp. conglobata.

E. dumosa var. conglobata R.Br. ex Benth., Fl. Austral. 3: 230 (1867); E. incrassata var. conglobata (R.Br. ex Benth.) Maiden, Crit. Revis. Eucalyptus 1: 96, 100 (1904). T: Port Lincoln, S.A., C.Wilhelmi s.n.; syn: K, NSW; south coast, S.A., 1802, R.Brown s.n.; syn: BM, CANB, E, K, NSW.

Mallee to 5m tall with coarse branchlets and foliage, or rarely a tree to 20 m tall. Forming a lignotuber.
Bark smooth throughout, shedding in short strips, pale grey, pale coppery, brown to green.
Branchlets with oil glands in the pith.
Juvenile growth (coppice or wild seedling to 50 cm tall): stems square in cross-section; juvenile leaves always petiolate, opposite for few nodes then alternate, ovate to broadly lanceolate, 5.5–11.5 cm long, 3–5 cm wide, base tapering or rounded, dull blue-green.
Adult leaves thickish and stiff, alternate, petioles 1–2.5 cm long; blade lanceolate, 7–13 cm long, 1.5–4 cm wide, base tapering to petiole, concolorous, usually dull bluish green sometimes maturing slightly glossy green, side-veins greater than 45° to midrib, reticulation dense to very dense, broken, intramarginal vein close to margin, oil glands intersectional.
Inflorescence axillary unbranched, sessile or with stout peduncles to 0.7 cm long, buds 7 per umbel, sessile to rarely shortly pedicellate (pedicels 0–0.2 cm long). Mature buds crowded, stout, ovoid to obovoid (0.7–1.5 cm long, 0.5–0.8 cm wide), green to yellow, scar present, outer operculum shed early, inner operculum usually conical, rarely rounded or beaked (0.4–0.9 cm long), hypanthium angled, stamens inflexed, anthers cuboid to wedge-shaped, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, stigma blunt, locules 3 to 5, the placentae each with 4 vertical ovule rows. Flowers white.
Fruit sessile, tightly clustered (but free), more or less hemispherical but flattened on one side, 0.5–1 cm long, 0.7–1.1 cm wide, disc usually descending, valves 3 to 5, exserted or at rim level.
Seeds reddish brown and glossy, 1.5–3 mm long, flattened-ovoid and often slightly angular in outline, dorsal surface shallowly reticulate, occasionally lacunose, hilum ventral.

Cultivated seedlings (measured at ca node 10): cotyledons reniform; stems square in cross-section; leaves always petiolate, opposite for 2 to 5 nodes then alternate, ovate to deltoid, 6–8.5 cm long, 2.5–6.5 cm wide, base truncate to tapering, dull, green to grey-green.

Flowering has been recorded in January, February, November and December.

Eucalyptus conglobata is a species of mallee or small tree, widespread along south coastal and subcoastal Western Australia, east to Toolinna Cove, and disjunctly in South Australia only on the southern Eyre Peninsula, including Boston Island near Port Lincoln. The bark is smooth, adult leaves dull blue-green maturing glossy green, buds and fruit sessile in umbels of seven.

In the classification of Brooker (2000) Eucalyptus conglobata belongs in Eucalyptus subgenus Symphyomyrtus section Dumaria having these features: buds initially with two opercula the outer shed early, stamens strongly inflexed, ovules in 4 rows on the placentae and cotyledons reniform. Within section Dumaria the species belongs to a large sub-group of closely related species (series Rufispermae, 37 described species and subspecies) diagnosed by glandular pith in the branchlets, anthers cuboid to wedge-shaped, versatile, and by the reddish brown and glossy, flattish seeds which are unique to the series.

Eucalyptus conglobata is distinguished in the series Rufispermae by the completely sessile buds and squat fruits, the latter often being wider than long. It is a variable species, in leaf width, peduncle length and bud and fruit size.

There are two subspecies:

E. conglobata subsp. conglobata
The typical coarse-leaved and stout-budded form with fruits 0.7–1.1 cm diameter, occurring on limy substrates near Port Lincoln in South Australia but also common in Western Australia from near Toolinna, Israelite Bay to Esperance and inland as far as Salmon Gums and Mt Ney. It grows to be a lignotuberous tree on Boston Island east of Port Lincoln.

E. conglobata subsp. perata.
This form, with much finer leaves and smaller buds, and fruits 0.5–0.7 cm diameter, is common throughout the Western Australian part of the species range west of Esperance. It has been collected in many places from Pingrup, Dumbleyung, Nyabing, Borden, Stirling Ranges, Jerramungup, Bremer Bay, Ravensthorpe Range, Fitzgerald River National Park.

The mallee subsp. conglobata is unlikely to be confused with any other species in the Port Lincoln area. In the Esperance hinterland there are several closely related species, viz. E. valens, which is a tree (mallet) with more glossy adult leaves, sessile buds and fruit very like subsp. conglobata in size; E. pileata, a mallee with umbels on peduncles to 1.5 cm long and pedicellate cylindrical to pyriform buds with operculum always wider than the base of the bud; E. spreta, a slender mallet often branching low, with small always pedicellate ovoid to cylindrical buds and cupular fruit to 0.7 cm diameter.

Subsp. perata is often confused with the closely related E. phenax subsp. phenax. Subsp. perata is weakly separated from E. phenax subsp. phenax in having consistently sessile  ovoid buds (0.5-0.9 cm long), compared with the usually shortly pedicellate ovoid-cylindrical buds (0.7-1.1 cm long) of E. phenax subsp. phenax . To make it even more difficult these two taxa probably intergrade where their ranges abut e.g. north of Ravensthorpe.

Eucalyptus conglobata: Latin conglobatus, like a ball, allusion unknown but presumably alluding to the cluster of sessile buds and fruits.

subsp. perata: Latin peratus, western, alluding to its occurrence in relation to the subsp. conglobata .