Corymbia

Corymbia
Corymbia ficifolia, Flowers
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Myrtales
Family:	Myrtaceae
Genus:	Corymbia K.D.Hill & L.A.S.Johnson, 1995
Type species
Corymbia gummifera (Gaertner) K.D. Hill & L.A.S. Johnson
Diversity
about 113 species

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 "eucalypts". 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.^[1] 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.^[2] 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.^[3]

Species

See also: List of Corymbia species

Corymbias are readily distinguished as "gum trees" that form corymb inflorescences. 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:

• Corymbia aparrerinja (Ghost Gum)
• Corymbia calophylla (Marri or Port Gregory Gum).
• Corymbia citriodora (Lemon-scented Gum). A tall, smooth-trunked tree native to central and northern Queensland 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 eximia (Yellow Bloodwood)
• Corymbia ficifolia (Red Flowering Gum).
• Corymbia henryi (Large Leaved Spotted Gum).
• Corymbia maculata (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 Wales and south-east Queensland 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 Australia.
• Corymbia ptychocarpa (Swamp bloodwood). Native to Western Australia, this species is a very popular garden plant.

• 

  Corymbia, capsules (Fruit)

• 

  Corymbia, flowers

• 

  Corymbia, capsules (Fruit

References

1. ^ Hill, Ken D.; Johnson, L.A.S. (1995). "Systematic studies in the Eucalypts 7. A revision of the bloodwoods, genus Corymbia (Myrtaceae)". Telopea 6: 185–504. 
2. ^ Parra-O., Carlos; Bayly, Michael (2006). "ETS sequences support the monophyly of the eucalypt genus Corymbia (Myrtaceae)". Taxon 55 (3): 653–63. JSTOR 25065641. 
3. ^ Parra-o., Carlos; Bayly, Michael J.; Drinnan, Andrew; Udovicic, Frank; Ladiges, Pauline (2009). "Phylogeny, major clades and infrageneric classification of Corymbia(Myrtaceae), based on nuclear ribosomal DNA and morphology". Australian Systematic Botany 22 (5): 384-99. doi:10.1071/SB09028.  edit

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 Arboretum