Myrtaceae > Subfamily Myrtoideae > Tribe Eucalypteae.
Angophora, Corymbia and Eucalyptus are closely related and commonly known collectively as “eucalypts”.
For more information on their main features see Myrtaceae > Eucalyptus > 1 Eucalypts – Gums.
A major reclassification in 1995 saw around 80 Eucalyptus species transferred to a Corymbia genus.
These were mostly the bloodwoods and ghost gums.
Almost all of the around 100 (95, 115) species are native to Australia.
They are mostly trees but there are some multi-stemmed malle-like species.
They have a dense crown and can grow new shoots from the base (coppice).
Bark can be:
a.) Rough, fibrous and breaking into small many angled pieces.
b.) Smooth bark that falls in angled flakes or short strips.
Tessellated bark may remain on all of the trunk or just the base.
Leaves, on a petiole are of 2 types.
a.) Juvenile leaves are opposite at the first few nodes.
Mostly on a petiole they can be ovate, nearly round or lance-shaped.
They often have stiff hairs and the oil glands are prominent.
b.) Further up the stems the ovate to lance-shaped adult leaves become alternate.
Both sides are usually the same colour but the lower may be paler.
The lateral veins are very close and there are oil glands.
Terminal inflorescences are a branched cluster (panicle) of corymbs#.
The primary peduncle branches and these may branch again.
The terminal peduncles have flowers, on a pedicel in groups of up to 7.
There is a hypanthium of fused sepal, petal and stamen filament bases.
The 5 sepal lobes on it are fused to form an outer operculum.
The 5 petal lobes form an inner operculum over the developing stamens and ovary.
The outer operculum may be shed before or with the inner one.
The numerous stamens, in more than one whorl are on the rim of the hypanthium.
The oblong dorsifixed anthers open through long slits.
The inferior to half inferior ovary has numerous ovules.
Fruit are a loculicidal capsule with the disc and the (4) 5 valves recessed in the hypanthium.
The 5 to 20 mm wide capsules are usually woody but a few can be thin.
The seeds may or may not have a wing.
# The genus name comes from the corymbs and almost all authoritative descriptions say the inflorescences are clusters or panicles of corymbs.
However many are umbels so the term ‘umbellaster’, meaning umbel-like is sometimes used rather than corymb.
In an umbel all the flowers are attached to the tip of the peduncle.
In a corymb they are attached at the tip and down the peduncle.
The lower ones have a longer pedicel so all the flowers end at around the same level.
The Royal Botanic Gardens of Victoria website has ‘umbel or corymb’.
An example is Corymbia ptychocarpa, previously Eucalyptus ptychocarpa which has flowers in umbels.
J.F.
