Red gum

Eucalyptus camaldulensis subsp. simulata Brooker & Kleinig, Field Guide to Eucalypts volume 3, p. 371, (1994).

T: Queensland: Laura River at crossing north of Laura, 15° 33' S, 144° 27' E, 5 November 1992, M.I.H.Brooker 11358 & D.A.Kleinig; holo: CANB; iso: AD, BRI, MEL, NSW. Image of type specimen held at CANB   

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Description

A medium sized to tall tree to 35 m tall. Forming a lignotuber.
Bark smooth throughout, often powdery, predominantly white, cream or grey but with patches of pink, red or brown.
Juvenile growth (coppice or field seedlings to 50 cm): not seen.
Adult leaves alternate, petiole 2–4 cm long; blade lanceolate, sometimes falcate, 11–25 cm long, (1)2–3.5 cm wide, base tapering to petiole, margin entire, concolorous, dull or glossy, green, side-veins acute or at an angle greater than 45° to midrib, densely reticulate, intramarginal vein parallel to and well removed from margin, oil glands numerous, island.
Inflorescences axillary unbranched, peduncles 0.7–1.8 cm long; buds 7, 9 or ?11 per umbel, pedicellate (pedicels 0.4–0.6(1) cm long). Mature buds narrowly ovoid ((0.9)1.1–1.8 cm long, 0.35–0.6 cm wide), green to yellow or creamy, scar present, operculum horn-shaped, (0.8)1–1.6 cm long, stamens erect, anthers cuboid to oblong, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, stigma tapered, locules (3) 4, the placentae each with 6 vertical ovule rows. Flowers white.
Fruit pedicellate (pedicels 0.3–0.8(1) cm long), hemispherical, 0.2–0.4 cm long, 0.5–0.8 cm wide, disc raised steeply-vertical to convex to oblique to concave, valves (3) 4, strongly exserted.
Seed light brown to yellow, 1–1.2 mm long, cuboid or pyramidal, dorsal surface smooth, hilum terminal.

Cultivated seedling (measured at node 10): cotyledons small, oblong to reniform, green above, purple beneath; stems square in cross-section, sometimes winged also, usually non-glaucous but sometimes glaucous; leaves always petiolate, opposite for ca 4 to 7 nodes then alternate, ovate to lanceolate, 7–14.2 cm long, 2–4.5 cm wide, dull, green, discolorous, rarely slightly glaucous.

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Notes

Eucalyptus camaldulensis is the most widespread species of eucalypt in Australia occurring in every mainland State. It is notably a tree of riverine sites whether of permanent or seasonal water. The species over its whole distribution is distinguished by the seeds which are cuboid, yellow to brownish yellow and have two seed coats (all other red gums have seeds with a single dark brown to black seed coat).

Across its entire range, the operculum shape in E. camaldulensis is highly variable. In the past, this character has been used to break up the group into different varieties or subspecies. The entire complex is currently under revision and new varieties or subspecies may be described or extant ones rationalised. Until this work is completed, we have decided to adopt a conservative view of E. camaldulensis. At present we recognise the following taxa:

var. camaldulensis
This is the most abundant form of the species in temperate south-eastern Australia and dominates the Murray-Darling river systems, but also occurs on lower Eyre Peninsula, Kangaroo Island, Yorke Peninsula, the south-east of South Australia and the adjacent Glenelg River system and intervening plains of western Victoria, and streams as far east as Sale in eastern Victoria. Var. camaldulensis is distinguished by the opercula which are normally strongly beaked and the non-glaucous, green, lanceolate juvenile leaves.
In the upper reaches of the Darling River in New South Wales and into the Moonie–Condamine region of Queensland is a form of E. camaldulensis with tapering to weakly beaked buds and non-glaucous juveniles. This form was described as E. camuldulensis var. acuminata. The authors of EUCLID have tentatively placed this under var. camaldulensis until further revisionary work is carried out.
At Mount Macintyre, north-west of  Mount Gambier, South Australia, a relatively robust-fruited red gum was described as Eucalyptus mcintyrensis in 1922, by J.H. Maiden, with the note "This appears to be a hybrid in which E. rostrata [=E. camaldulensis] is concerned. What the other parent is, if it is a hybrid, is less clear. It appears to be E. ovata, which is common in the district." Recent collections by the authors of EUCLID of specimens matching both E. mcintyrensis and E. camaldulensis var. camaldulensis from this locality had identical yellow, double-coated seed, and identical uniform progeny (seedlings). On this basis we suggest that E. mcintyrensis is a localized aberrant form of  E. camaldulensis with broader fruit with flatter disc, occurring within a typical E. camaldulensis var. camaldulensis population, and not a hybrid.

var. obtusa
This variety is distributed west and north-west of the Murray-Darling basin of south-eastern Australia through most of arid central Australia and the drier parts of the wet/dry tropics. It occurs from western New South Wales, through much of central, western and northern Australia, extending north to the Gulf of Carpentaria hinterland in Queensland, to Katherine and Annaburoo and near Bulman in the Top End of the Northern Territory, and west through the Victoria River region to the upper Drysdale River catchment in the Kimberley region of Western Australia, and south to about Moora and the Moore River north of Perth. Also through central Australia and northern South Australia wherever stream lines occur and the irregular but low rainfall is adequate.

The buds of var. obtusa have opercula which are normally conical to obtuse or quite rounded, and the juvenile and intermediate leaves are bluish and often glaucous. Adult leaves are not usually glaucous, rather being blue-green to green. Where glaucous crowns are obvious it is usually due to leaves that are developmentally intermediate in nature, i.e. are sub-adult. Such populations have been noted along the Nogoa River west of Springsure, and the upper Warrego River south-west of the Carnarvon Ranges in central Queensland. Populations west of Broken Hill, New South Wales, originally described as var. subcinerea are here included in var. obtusa. Trees along intermittent streams in the area west from Broken Hill to the Flinders Ranges in South Australia often are very waxy on juveniles, branchlets and buds, have small buds (unlike var. subcinerea) and are of uncertain status. The small-budded dryland populations on stoney limestone plains near Elliston on the Eyre Peninsula of South Australia, with non-glaucous adult parts and glaucous juvenile growth, are also of uncertain status. Populations on seasonal streams in the Pilbara region of Western Australia, with their extremely glossy green adult leaves, are currently included in var. obtusa. Trees of var. obtusa with glossy green adult leaves occur also in the Kimberley region.

subsp. simulata
A medium-sized tree, restricted to some river systems on the Cape York Peninsula in far north Queensland from the Kennedy River crossing just north of Laura, west to the Mitchell River at Koolata Station, then south-east to the Walsh River area just west of Mareeba, with two disjunct populations further south, one at the Fanning River near Dotswood south-west of Townsville and the other near Lake Elphinstone north-west of Nebo. Subsp. simulata  has the long narrow acute operculum like that of E. tereticornis but has the yellow, double-coated seed of E. camaldulensis. It is likely that this taxon is of hybrid origin between E. camaldulensis and E. tereticornis, or alternatively, E. tereticornis with yellow seed.

MORE ABOUT RED GUMS AND OTHER ASSOCIATED GROUPS

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Flowering Time

Flowering has been recorded in July and August.

Origin of Name

Eucalyptus camaldulensis: after Camalduli in Italy where a tree was grown in a private estate garden in the early 19th. century. Material from this tree was used by Frederick Dehnhardt, Chief Gardener at the Botanic Gardens in Naples, to describe this species in 1832. The seed used to grow this tree could only have come from south-eastern Australia, though the exact collection location is unknown.

subsp. simulata: Latin similatus, resembling, alluding to the buds which are indistinguishable from E. tereticornis.

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