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Eucalyptus signata

Scribbly Gum

Family: Myrtaceae

A tree growing to 25 metres tall, forming a lignotuber.

Occurring from northern Sydney up the New South Wales coast and northern tablelands to beyond the Queensland border.

It grows in dry sclerophyll forests as well as and swampy areas at low altitude, on sandy soils or sandstone.

Bark is smooth, with scribbles, white or yellow, shedding in short ribbons. The bark is typical of the scribbly gum, being blotchy white with scribbles caused by scribbly gum moth-larvae.

Eucalyptus spp. have simple and usually alternate adult leaves with juvenile leaves starting off opposite to alternate (disjunct). In this species, juvenile leaves / coppicing growth are/is disjunct, broad-lanceolate, dull grey-green. Adult leaves are disjunct, lanceolate, to 14 cm long and to 3 cm wide, green to blue-green.

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, Flowers per umbellaster are around 11 or more. Mature buds are ovoid or clavate (a 3-dimensional shape; club shaped; thickened at one end) to 6 mm long to 4 mm in diameter. Flowering generally between July and September

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 hemispherical, or pyriform (having the form of a pear) to 7 mm long and to 7 mm diameter, reddish in colour on the top with valves to rim-level. 

In the garden

This species is not overly common in cultivation. It would be a useful tree in an open ridge-top or garden on a hill, especially on sandy soils. Can grow to over 20 metres so not suited to small gardens. Attractive tree in a sunny open landscape. It does not grow all that large – especially if planted in shallow soils. Lends to bushy landscapes with its white bark.  

A primary Koala tree in its natural range. This species is one of 27 more common Eucalypt and Corymbia plants eaten by them.

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

Eucalyptus 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 was not accepted by all herbaria. Genetic research continues as the taxa are known to intergrade with likely hybridisation. Some taxa may be lumped in the future. 

Regenerates readily from fire, from lignotuber and epicormic shoots. Can also regenerate from seed.

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).

signata – from the Latin signatus, meaning ‘marked’ – likely referring to the scribbles on the trunk.

This species is not know 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 signata profile page              https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~signata

EUCLID – Eucalypts of Australia – Centre for Australian National Biodiversity Research – Eucalyptus racemosa subsp. racemosa profile page.                                          https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~racemosa

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