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Eucalyptus sclerophylla (now Eucalyptus racemosa)

Hard-leaved Scribbly Gum, Narrow-leaved Scribbly Gum, Snappy Gum

Family: Myrtaceae

Note: this species is now considered to be indistinguishable and equivalent to Eucalyptus racemosa by the National Herbarium of NSW as well as others. This profile has been kept for historic purposes.

A tree, growing up to 20 metres tall with a wide canopy spread.

Its natural range is (was) considered to be north from Jervis Bay to around Pokolbin in the Hunter Valley. Around Sydney, it was thought to occur in the general western areas in vegetation types such as Castlereagh Scribbly Gum Woodland and Agenes Banks Woodland in western Sydney. It was also frequently observed in the southern highlands area of NSW.  

Smooth barked, with shedding bark of white or grey. Scribbles often found on the bark.

Eucalyptus spp. have simple and usually alternate adult leaves with juvenile leaves starting off opposite to alternate (disjunct). In this species, adult leaves are to 16 cm long, to 4 cm wide, lanceolate to falcate, grey-green in colour, on both sides of the leaf and with a strong smell. Juvenile leaves can also be large. 

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, white flowers form between November and February. The flower buds are in umbellasters of 11 or more, in leaf axils, to 5 mm long and 3 mm wide, with a hemispherical rounded operculum / calyptra.

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 capsule is cup-shaped, hemispherical to spherical, to 7 mm long and to 5 mm wide with the valves near rim level. The top of the capsule is red-brown when ripe.

In the garden

Not an overly common tree in cultivation but very useful on sandy soils. Is seen as a street tree in some places. Would be suited to open gardens on sandy soils and they can be kept as a mallee. In their natural habitat, they are usually not overly large, but should best be avoided in small gardens.

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.

Also: see notes for Eucalyptus racemosa

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. 

Other information

Eucalyptus is one of three similar genera that are commonly referred to as “eucalypts”, the others being Corymbia and Angophora.

There have historically been 5 scribbly gum taxa recognised in NSW (E. haemastoma, E. racemosa, E. rossii, E. sclerophylla and E. signata). Recent studies have lumped these taxa into 3 entities as follows:
Eucalyptus haemastoma
– Eucalyptus racemosa subsp. racemosa
– Eucalyptus racemosa subsp. rossii

However, this revision has not been accepted by all herbaria. Genetic research still continues as the taxa are known to intergrade with likely hybridisation. Taxa may be lumped in the future.

At the time of writing this profile, it seems Eucalyptus sclerophylla has been absorbed into Eucalyptus racemosa according to the NSW Herbarium. 

This species regenerates readily from fire through the lignotuber and epicormic shoots as well as from the seedbank. 

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).

sclerophylla – is from the Ancient Greek words skleros (Σκληρός) meaning “hard” or “tough” and phylla (φύλλα) meaning “leaves” – referring to the toughness of the leaves. There is a type of leaf tissue referred to as “sclerenchyma” which is present in the leaves of many Australian plants.

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 racemosa profile page      https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~racemosa

EUCLID – Eucalypts of Australia – Centre for Australian National Biodiversity Research – Eucalyptus racemosa subsp. racemosa profile page https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_racemosa_subsp._racemosa.htm

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