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Eucalyptus umbra

Broad-leaved White Mahogany

Family: Myrtaceae

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

It grows in the high rainfall coastal areas of New South Wales between Sydney and Grafton, northwards to south-eastern Queensland.

It is typically found in dry sclerophyll forest or woodland, usually on poor shallow dry soils (sandstone as well as clay-based soils). It can be a much smaller tree on ridgetops on the coast.

The bark is persistent throughout, thin, grey to red-brown and stringy (stringybark / mahogany).

Eucalyptus spp. have simple and usually alternate adult leaves with juvenile leaves starting off opposite to alternate (disjunct). In this species, juvenile foliage / coppicing regrowth have sessile leaves that are broadly ovate to lanceolate, potentially to 20 cm long and to 10 cm wide, held horizontally and arranged in opposite pairs with the bases surrounding the stem.
Adult leaves are arranged alternately, the same shade of green on both sides, lanceolate to falcate, to 18 cm long and to 5 cm wide, tapering to a petiole to 20 mm long. The overall canopy gives an appearance of very broad leaves.

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 clustered in an umbellaster of 7 to 11, which are then mostly arranged in panicles on the ends of branchlets. Mature buds are oval, about 6 mm long and 3 to 4 mm wide with a conical to beaked operculum / calyptra. Flowering occurs from September to February and the flowers are white.

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 capsules are cup-shaped to hemispherical, to 7 mm long and to 10 mm wide with the valves near rim level or below it. The apperance of the valves of these fruit are a good identifying feature after it is observed repeatedly. 

In the garden

Not a very popular plant in cultivation. However, it makes a good shade tree and is often found as a smaller tree, especially on steep upper slopes. However, it is not suited for small gardens. It does lend to medium to large landscapes, in a sunny-open position on sandy or heavier soils. It would make a nice specimen tree in an open lawn area.

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.

In a ridge-top garden situation, they may not get overly large and so may lend to landscapes in these areas.

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

Regenerates from lignotuber and epicormic growth after fire.

E. umbra is very similar to E. carnea (which used to be treated as a subspecies). E. carnea which occurs on dry sites on subcoastal hills from Newcastle to Gympie, is mainly distinguished from E. umbra on fruit features, having a narrower disc to the fruit and is more variable in placement of the disc (concealed, descending or easily visible and more or less flat, never having the broad disc and flat-topped fruit of E. umbra.

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).

umbra – Latin word meaning “shade” or “shadow” (root of “umbrella”), referring to the broad-leaved canopy produced by the tree.

This species is not considered to be at risk 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 umbra plant profile page        https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~umbra

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

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