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Eucalyptus rubida

Candlebark, Ribbon Gum or White Gum

Family: Myrtaceae

A tree, growing to 40 m high (although usually seen much smaller in many habitats).

It is almost purely confined to the tablelands-areas in NSW, growing to both borderlines, possibly extending just into Queensland around Warwick, and extending through most of Victoria as far west as Horsham. It also grows in Tasminia, roughly between Hobart and Greak Lake / Yingina.

It is typically found on shallow rocky soils or alluvial flats (sands to loams) on hills and slopes in cold areas, forming part of dry sclerophyll woodland and forests. 

Bark is smooth, powdery, greyish or pink and is shed in long ribbons but there is sometimes persistent fibrous bark near the base of the trunk. Large mature trees have bark resembling the ‘wax of a burning candle’ – hence one of the common names. 

Eucalyptus spp. have simple and usually alternate adult leaves with juvenile leaves starting off opposite to alternate (disjunct). In this species, juvenile/coppicing leaves are sessile, glaucous, and more or less round, to 60 mm wide, arranged in opposite pairs – blue-ish to blue-green or more green. This appearance of this growth is a very useful and relied-on identification feature. Adult leaves are arranged alternately, lanceolate to falcate, to 175 mm long and to 35 mm wide, tapering to a petiole to 35 mm long, usually mid-green or blue-green in colour. At times, leaves can have a really thin texture. 

The primary inflorescence of “eucalypts” (Angophora / Corymbia / Eucalyptus) is an umbellaster (an umbel-like cluster of flowers). In the flowers of Corymbia and Eucalyptus, the petals and sepals are fused into the distinctive calyptra / operculum (bud cap) which is shed when the flower opens (in some species, 2 bud caps (opercula) are shed). The flowers are conspicuously staminate – where many stamens are basically taking over the role of the petals, all surrounding one central carpel. In this species, the flower buds are arranged in leaf axils in umbellasters of mostly 3 but sometimes to 7, up to 9 mm long and to 5 mm wide with a conical to rounded operculum/ calyptra (when in 3s – they are another useful identification feature, especially when combined with the juvenile growth). Flowers are white and occurs from December to April.

The fruit of eucalypts are a woody capsule (commonly called ‘gum nuts’) which come in a wide variety of shapes with the top part having a sunken, flat or raised disc and with the valves inserted, disc-level, exserted to strongly exserted. In this species, the fruit is a capsule, hemispherical or bell-shaped to 6 mm long and 8 mm wide with the valves near rim level or protruding slightly (exserted).

In the garden

A moderate to fast growing ornamental tree adaptable to most well drained soils. Not overly common in cultivation but lends itself to large or open gardens located in cold areas on the tablelands. It can grow in sandy soils but will also tolerate heavier soils. Would do well in ridge-top and upper slope gardens in full sun. Not recommended for small residential gardens. The trunk can also exhibit interesting hues / shades through the year. This species is strongly frost-tolerant. 

When flowering, trees are sought out for honey production.

Eucalypts can suffer problems from, caterpillars, leaf eating beetles, psyllids and borers to name a few. In undisturbed conditions, the numbers of eucalypt-feeding insects and their predators and parasites are in balance, so that they rarely cause tree death and most trees quickly recover from attack. In a home situation nature can get out of balance.

Propagation

Eucalypts can be propagated by seeds which is most common method or grafting.
Cuttings are difficult to start, but can be used in some species. For further information refer to: http://anpsa.org.au/APOL2007/sep07-s1.html

Other information

There are three subspecies currently recognised in NSW:
Eucalyptus rubida subsp. rubida – occurring on the central and southern tablelands of NSW, Victoria and Tasmania. 
– Eucalyptus rubida subsp. barbigerorum – occurring only on the Northern tablelands of NSW (possibly extending into Queensland).
– Eucalyptus rubida subsp. septemflora – reported to occur in the NSW-Victorian border area. 

The subspecies barbigerorum is listed as threatened with extinction and classified as “vulnerable” at the State and Commonwealth level.
The subspecies septemflora is confined to the southern tablelands and has umbellasters of 7 flower-buds (hence the name).

This species regenerates readily from the lignotuber and epicormic shoots after fire. 

Eucalyptus is one of three similar genera that are commonly referred to as “eucalypts”, the others being Corymbia and Angophora. It is well-known that Eucalyptus is a large and diverse genus. Between 700 and 950 known species are reported, occurring as far north as The Philippines, as well as Indonesia, New Guinea, Timor and Australia. Only 16 species reportedly occur outside Australia. They occur in all Australian states. NSW currently has about 250 species. (See this website for some detailed information: https://apps.lucidcentral.org/euclid/text/intro/learn.htm).

Eucalyptus – from Greek, eu, “well” or “true” and calyptus, referring to the calyptra (καλύπτρo) or operculum, which is a bud cap or covering which covers the developing flowers. The calyptra is a fusion of petals and/or sepals and is shed when the flower opens, leaving a flower with many stamens (staminate) surrounding one female part (carpel).

rubida – from the Latin word rubidus meaning “red”, referring to the seasonally reddish bark.

This species is not considered to be at risk of extinction in the wild. 

Field Guide to Eucalypts – Vol 1 South Eastern Australia M.I.H.Brooker and D.A.Kleinig. Blooming Books.

NSW Flora Online (PlantNET) – Eucalyptus rubida profile page
https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=in&name=Eucalyptus~rubida~subsp.+septemflora

EUCLID – Eucalypts of Australia – Centre for Australian National Biodiversity Research – Eucalyptus rubida profile page                https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_rubida_subsp._rubida.htm

By Jeff Howes. Editing and additional text by Dan Clarke.