Corymbia
Encyclopedia
Corymbia is a genus of about 113 species of tree that were classified as Eucalyptus
species until the mid-1990s. It includes the bloodwoods, ghost gums and spotted gums. The bloodwoods had been recognised as a distinct group within the large and diverse Eucalyptus genus since 1867. Molecular research in the 1990s, however, showed that they, along with the rest of the Corymbia section, are more closely related to Angophora
than to Eucalyptus, and are probably best regarded as a separate genus. All three genera - Angophora, Corymbia and Eucalyptus - are closely related, often difficult to tell apart, and are still commonly and correctly referred to as "eucalypt
s". Groups of naturalists and conservationists do not recognise the Corymbia genus and still categorise its species within Eucalyptus
.
Botanists Ken Hill and Lawrie Johnson were the first to define the genus Corymbia in 1995, identifying the bloodwoods, ghost gums and spotted gums as a group distinct from Eucalyptus. Since then, there have been ongoing investigations into the relationships between the genera. Genetic analysis of ETS and ITS sequences of DNA in 2006 by Carlos Parra-O and colleagues of 67 taxa (47 of which were within Corymbia) yielded Corymbia and Angophora as each others' closest relatives, with the genus Eucalyptus as an earlier offshoot. The small genera Eucalyptopsis
, Stockwellia and Allosyncarpia
formed a clade which arose earlier still. In 2009, Parra-O and colleagues added more taxa and published a combined analysis of nuclear rDNA (ETS + ITS) and morphological characters published to clarify relationships within the genus. This confirmed two main clades, which they defined as the subgenera Corymbia and Blakella.
Corymbias are readily distinguished as "gum trees" that form corymb inflorescence
s. A corymb has the appearance of a compound umbel
, however it has irregularly lengthened pedicels
that help form a flat-topped inflorescence.
The Angophora genus is a lot harder to distinguish from the Eucalyptus genus. The main distinguishing feature that separates the two, is that Angophoras have opposite leaf attachments at maturity and most eucalyptuses in most species don't. However juvenile leaves of eucalypts are often opposite.
Some of the better known corymbias are:
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
species until the mid-1990s. It includes the bloodwoods, ghost gums and spotted gums. The bloodwoods had been recognised as a distinct group within the large and diverse Eucalyptus genus since 1867. Molecular research in the 1990s, however, showed that they, along with the rest of the Corymbia section, are more closely related to Angophora
Angophora
Angophora is a genus of ten species of trees or large shrubs in the myrtle family , native to eastern Australia. It is closely related to Corymbia and Eucalyptus, and all three are often referred to as "eucalypts". The differences are that Angophora have opposite leaves rather than alternate, and...
than to Eucalyptus, and are probably best regarded as a separate genus. All three genera - Angophora, Corymbia and Eucalyptus - are closely related, often difficult to tell apart, and are still commonly and correctly referred to as "eucalypt
Eucalypt
Eucalypts are woody plants belonging to three closely related genera:Eucalyptus, Corymbia and Angophora.In 1995 new evidence, largely genetic, indicated that some prominent Eucalyptus species were actually more closely related to Angophora than to the other eucalypts; they were split off into the...
s". Groups of naturalists and conservationists do not recognise the Corymbia genus and still categorise its species within Eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
.
Botanists Ken Hill and Lawrie Johnson were the first to define the genus Corymbia in 1995, identifying the bloodwoods, ghost gums and spotted gums as a group distinct from Eucalyptus. Since then, there have been ongoing investigations into the relationships between the genera. Genetic analysis of ETS and ITS sequences of DNA in 2006 by Carlos Parra-O and colleagues of 67 taxa (47 of which were within Corymbia) yielded Corymbia and Angophora as each others' closest relatives, with the genus Eucalyptus as an earlier offshoot. The small genera Eucalyptopsis
Eucalyptopsis
Eucalyptopsis is a genus of plant in family Myrtaceae. It contains the following species :* Eucalyptopsis papuana, C.T.White...
, Stockwellia and Allosyncarpia
Allosyncarpia
Allosyncarpia is a genus of the botanical family Myrtaceae....
formed a clade which arose earlier still. In 2009, Parra-O and colleagues added more taxa and published a combined analysis of nuclear rDNA (ETS + ITS) and morphological characters published to clarify relationships within the genus. This confirmed two main clades, which they defined as the subgenera Corymbia and Blakella.
Species
- See also: List of Corymbia species
Corymbias are readily distinguished as "gum trees" that form corymb inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s. A corymb has the appearance of a compound umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....
, however it has irregularly lengthened pedicels
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
that help form a flat-topped inflorescence.
The Angophora genus is a lot harder to distinguish from the Eucalyptus genus. The main distinguishing feature that separates the two, is that Angophoras have opposite leaf attachments at maturity and most eucalyptuses in most species don't. However juvenile leaves of eucalypts are often opposite.
Some of the better known corymbias are:
- Corymbia aparrerinjaCorymbia aparrerinjaCorymbia aparrerinja commonly known as Ghost Gum, is an evergreen tree that is native to Central Australia....
(Ghost Gum) - Corymbia calophyllaCorymbia calophyllaCorymbia calophylla is a bloodwood native to Western Australia. Common names include Marri and Port Gregory Gum, and a long standing usage has been Red Gum due to the red gum effusions often found on trunks.It is distinctive among bloodwoods for its very large buds and fruit Corymbia calophylla...
(Marri or Port Gregory Gum). - Corymbia citriodora (Lemon-scented Gum). A tall, smooth-trunked tree native to central and northern QueenslandQueenslandQueensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
and planted in many other areas, well known for the beauty of its white or light grey trunk and instantly recognisable by the strong lemon scent of its leaves. - Corymbia eximiaCorymbia eximiaCorymbia eximia, commonly known as the Yellow Bloodwood, is a bloodwood native to New South Wales. It occurs around the Sydney Basin often in high rainfall areas on shallow sandstone soils on plateaux or escarpments, in fire prone areas. Growing as a gnarled tree to 20 m , it is recognisable by its...
(Yellow Bloodwood) - Corymbia ficifoliaCorymbia ficifoliaCorymbia ficifolia or the red flowering gum also known as Albany red flowering gum is one of the most commonly planted ornamental trees in the broader eucalyptus family....
(Red Flowering Gum). - Corymbia henryiCorymbia henryiCorymbia henryi or the Large-leaved Spotted Gum is a bloodwood found in eastern Australia. It occurs in north eastern New South Wales from around Coffs Harbour to near Brisbane in Queensland. The habitat is dry eucalyptus forest on sandy soils in fire prone areas.An attractive tree, up to 30...
(Large Leaved Spotted Gum). - Corymbia maculataCorymbia maculataCorymbia maculata , commonly known as Spotted Gum, is an endemic Australian tree.-Description:Spotted Gum is a medium to tall tree with a straight trunk, growing up to 70 metres in height. However, there is an old reference to a 91 metre tall tree...
(Spotted Gum). Another popular garden tree which sheds its bark in a distinctive irregular round patches which take on a range of different colours from cream through blue-grey to orange, pink or red. Native to coastal New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
and south-east QueenslandQueenslandQueensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
but planted in many areas, the Spotted Gum is also valued for its tough, fine-grained timber, which is used for tool handles and other applications where hardness and resistance to warping is essential, e.g. axle blocks for wooden cart wheels. - Corymbia opaca (Bloodwood). Native to Central AustraliaCentral AustraliaCentral Australia/Alice Springs Region is one of the five regions in the Northern Territory. The term Central Australia is used to describe an area centred on Alice Springs in Australia. It is sometimes referred to as Centralia; likewise the people of the area are sometimes called Centralians...
. - Corymbia ptychocarpaCorymbia ptychocarpaCorymbia ptychocarpa, formerly known as Eucalyptus ptychocarpa, is a species of eucalypt native to northwestern Australia. It was given its current name in 1995 with the creation of the genus Corymbia....
(Swamp bloodwood). Native to Western Australia, this species is a very popular garden plant.
External links
- A New Name for the Bloodwood and Ghost Gum Eucalypts
- A short essay about the eucalypts reclassification debate
- Currency Creek Arboretum Eucalypt Research at Currency Creek ArboretumCurrency Creek Arboretumthumb|right|270px|[[Dean Nicolle]] and [[Eucalyptus deanei]]thumb|right|270px|Eucalyptus conferruminataThe Currency Creek Arboretum is located in South Australia near the geographical feature and small town of Currency Creek, up from the mouth of the Murray River at Goolwa, and south of Adelaide...