River red gum

Eucalyptus camaldulensis var. obtusa Blakely, Key Eucalypts 135 (1934).

T; Nannine, W.A., Sept. 1910, W.V.Fitzgerald s.n.; syn: NSW; Balkara, W.A., 29 Sept. 1905, A.Morrison s.n.; syn: NSW; Strelly R., W.A., 1900, J.B.Cleland s.n.; syn: NSW; Alice Springs, N.T., 13 Jan. 1927, J.B.Cleland s.n.; syn: NSW; Daly Waters, N.T., July 1922, C.E.F.Allen s.n.; syn: NSW; Powell Ck, N.T., Aug. 1922, C.E.F.Allen s.n.; syn: NSW; Finke R., N.T., 1880, H.Kempe s.n.; syn: MEL, NSW; Mt Lyndhurst, S.A., Nov. 1899, M.Koch s.n.; syn: NSW ; Kuitpo, S.A., 16 Mar. 1923, J.B.Cleland s.n.; syn: K; Sandy Ck, 14 miles [c. 23 km] N of Gilgunnia, NSW, 7 June 1900, R.H.Cambage 1012; syn: NSW.

E. camaldulensis var. pendula Blakely & Jacobs in W.F.Blakely, Key Eucalypts 135 (1934). T: No. 4 bore, between Birdum & Daly Waters, N.T., 4 Aug. 1933, M.R.Jacobs 136; holo: NSW; iso: CANB. Image of type specimen held at CANB   

E. camaldulensis var. subcinerea Blakely, Key Eucalypts 135 (1934). T: Silverton, N.S.W., 22 Apr. 1921, R.H.Cambage 4343; syn: NSW; Charleville, Qld. 25 Sept. 1911, E.B.Atkins; syn: NSW.

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Description

Tree to 30 m tall. Lignotuber present or absent.
Bark smooth throughout, often powdery, predominantly white, cream or grey but with patches of pink, red or brown, branchlets rarely glaucous.
Juvenile growth (coppice or field seedlings to 50 cm): stem square and sometimes quite winged in cross-section, growing tips and young stems glaucous; juvenile leaves always petiolate, opposite for 4 to 7 nodes then alternate, lanceolate to ovate, 7.5–14.5 cm long, 2.5–7.5 cm wide, flat or undulate margin, blue-green or blue-grey or glaucous.
Adult leaves alternate, petiole 0.8–3.3 cm long; blade lanceolate or narrowly lanceolate or falcate, 5–28 cm long, 0.8–3.6 cm wide, base tapering to petiole, margin entire, concolorous, often glossy, green to blue-green, rarely glaucous, side-veins greater than 45° to midrib, densely reticulate, intramarginal vein parallel to and well removed from margin, oil glands numerous, island or rarely absent.
Inflorescences axillary unbranched, peduncles 0.5–2.8 cm long; buds 7, 9 or ?11 per umbel, pedicellate (pedicels 0.1–1.2 cm long). Mature buds ovoid to globular (0.5–1 cm long, 0.3–0.7 cm wide), green to yellow or creamy or glaucous, scar present, operculum broadly conical or rounded (0.3–0.8 cm long), stamens erect, or sometimes irregularly flexed, anthers cuboid to oblong, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, stigma blunt or tapered, locules 3 or 4, the placentae each with 6 vertical ovule rows. Flowers white.
Fruit pedicellate (pedicels 0.2–1.1 cm long), hemispherical, 0.2–0.6 cm long, 0.4–0.9 cm wide, disc raised-convex, valves 3 or 4, strongly exserted.
Seed light brown to yellow, 0.8–1.5 mm long, cuboid or pyramidal, dorsal surface smooth, hilum terminal.

Cultivated seedling (measured at node 10): cotyledons oblong to reniform; stems square in cross-section, sometimes winged also, usually at least slightly glaucous; leaves always petiolate, opposite for ca 4 to 9 nodes then alternate, ovate to narrowly lanceolate, 6–15 cm long, 0.8–5.5 cm wide, with base tapering to petiole, dull, glaucous, scarcely glaucous  or green to blue-green.

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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.

MORE ABOUT RED GUMS AND OTHER ASSOCIATED GROUPS

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Flowering Time

Flowering has been recorded in May, June, July, August, September, October, November, December and January.

E. camaldulensis has been used for heavy construction, railway sleepers, flooring, framing, fencing, plywood, veneer, turnery, firewood, charcoal production, gums, honey, ornamental, fuel, oils, medicinal (Aboriginal).

Both var. camaldulensis and var. obtusa have been noted to have become naturalized away from their natural distribution in areas of southern Western Australia, Victoria and Queensland.

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.

var. obtusa: Latin obtusus - obtuse, refers to the opercula.

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