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Behold! The Mighty Canthium
Kenneth McClymont
It is hard to pick a single favourite rainforest plant genus. So, I will relate to you one of my many choices, a genus containing species that, although quite common within local rainforests, are not often talked about (but should be!!). Therefore without further ado, behold the mighty canthiums!
The genus name Canthium is derived from the Malay word 'canti', which was the name given to a tree in Malacca which was the first described species of the genus. There are approximately 200 Canthium species worldwide, with Australia having 10-15 mostly endemic species. Local canthiums range in size from shrubs to small trees. They have entire, opposite leaves and bear small, sometimes tubular, perfumed flowers in loose or sometimes dense axillary clusters. Small rounded or lobed drupes are borne as fruit, ranging in colour from orange/red to shiny black. Many Australian species occur in drier inland areas, but quite a few local species occur in rainforest or on its margins.
There are six (now four, see footnote. Ed) described and one undescribed Canthium species occurring in rainforest communities around Brisbane.
Large-leaved canthium
Canthium lamprophyllum - derived from the Greek 'lampros', shining and 'phyllon', a leaf.
This is a large shrub or small tree to about 15 metres tall with a stem diameter up to 45cm. Recorded from littoral, subtropical and dry rainforests from about Woolgoolga, New South Wales to Cooloola, south-east Queensland. Locally I have seen it growing in riverine rainforest sites and in protected parts of drier rainforest patches. This is an attractive plant when spotted in the wild with its large shiny leaves (up to 13 cm) and perfumed flowers (February to June). It would make an excellent garden specimen tree or an authentic addition to a local rainforest garden planting.
Shiny-leaved canthium
Canthium odoratum - derived from the Latin 'odoratus', sweet smelling, in reference to this plant's perfumed flowers.
This is a large shrub or small tree to 10 metres (that would be an exceptionally large one!) with a stem diameter up to 25cm. It has been recorded in subtropical and more commonly dry rainforests from the Hunter River, New South Wales to New Guinea. This plant is common locally and can even be seen growing in eucalypt forests, mainly along stream banks or protected gullies. The fruit is eaten by birds and the foliage is used as fodder by cattle and other stock. This plant can be difficult to positively identify in the field as there are several distinct forms (according to leaf size) and some intergrading between this species and Canthium buxifolium (see below). The various forms may at some stage be separated taxonomically into distinct species.
In cultivation, this is a moderately slow growing, but hardy plant. Its characteristic horizontally layered branches and masses (and I mean masses!) of white, heavily perfumed flowers (October to January) make it an attractive and intriguing addition to any garden (and it’s not too large). Another interesting thing about the growth form of this plant is the peculiar swelling of the branchlet segments. The swollen branchlets are hollow inside and provide homes for a species of dark brown native ant. The ants actively tend scale insects which live inside the branchlet chamber and feed off the plant's vascular system, and in turn provide food secretions which sustain the ants (pers. comm. Frank Jordan). Another example of one of those fascinating and intimate relationships found within nature.
Stiff canthium
Canthium buxifolium - derived from Buxus, a genus of ancient box trees, and the Latin 'folium', leaf, because this Canthium has leaves similar to the Buxus genus.
This is a large shrub or small tree to about 7 metres, which is recorded in dry rainforest and eucalypt forest north from the Hastings River, New South Wales. In Queensland it is commonly found in the drier rainforests, eucalypt forests and Brigalow scrub. It is closely related to Canthium odoratum, but can be distinguished by its smaller (1.5 to 4cm long) blunt, shortly pointed leaves. This plant would be perfect for use in a dry garden, as it is very hardy. It is slow growing, but eventually turns into a dense screen plant with distinctive horizontally layered branches. Masses displays of white, perfumed flowers (mainly November to February) and the shiny black fruit that follow add to its appeal.
Small-leaved canthiums (See footnote. Ed)
Canthium vacciniifolium - derived from Vaccinium, the genus of the northern hemisphere cranberry and the Latin 'folium', a leaf, as this Canthium has leaves similar to the Vaccinium genus.
Canthium microphyllum - derived from the Greek 'micros', small, and 'phyllon', a leaf.
These are large shrubs or small trees to about 8 metres tall. Commonly recorded in dry rainforest from the Hastings River, New South Wales to north Queensland. Both the small-leaved canthiums have the smallest leaves (under 1.5cm) of all the local canthiums, and this makes them relatively easy to identify in the field (although distinguishing between the two species can be tricky). Pale yellow flowers with a reportedly unpleasant musty odour are borne (February to March), followed by small black fruits.
C.vacciniifolium normally occurs more commonly in the drier vine scrub/thickets of the inland, although both species can occur at the same site, eg. with C.vacciniifolium growing on the drier ridges and C.microphyllum in the protected moister gullies (pers. comm. W.J.F. McDonald). Additionally, both species possess the characteristic horizontally layered branches associated with many of the other Canthium species, although with a slight difference. The branchlets of these two species are distinctly zigzagged and the intricate branching associated with the branchlets makes them feel almost spiny to the touch.
Both the small-leaved canthiums are highly ornamental plants when used in the garden. Though slow growing, they are very hardy species, resistant to dry conditions and other extremes. These canthiums can be kept as pot plants for many years (I have several) and are excellent specimens for indoor use, especially when they put on a growth flush of miniature green new leaves, which distinctly contrasts with the darker green of the older leaves.
Coastal canthium
Canthium coprosmoides - derived from Coprosma, a shrub with similar leaves, and the Greek 'eidos', resembling, in reference to this canthium's similarity to the shrub Coprosma.
Coastal canthium is a big shrub/small tree, which has been recorded as growing up to 25 metres tall with a 50cm stem diameter (a very large example), but is usually seen as a much smaller dense-canopied plant when seen in the wild around Brisbane. It is commonly seen in remnant and regenerating rainforest and has been recorded growing in littoral and dry subtropical rainforest types.
This Canthium bears cream, fragrant flowers which fade to golden brown with age (mainly November to February). The fruit that follow are orange/red, glossy and edible (although not one that I would recommend as a taste treat). Again, this is rather slow growing, yet quite a tough plant that can handle a variety of conditions once established in the garden.
Canthium species (Cooroy)
This undescribed Canthium (I am told) is similar to coastal canthium (C.coprosmoides), but differs in having a larger leaf which ends in a distinctly more drawn out leaf tip. This new species is also more commonly found in the moister subtropical rainforest types relatively close to the coast that the typical C.coprosmoides (pers. comm. W.J.F. McDonald).
A few words about propagation
All local Canthiums can be grown easily from fresh seed that has had the flesh removed. Most species are amenable to grow th from stem cuttings. Try them out for yourself.
References
- Floyd, A.G. (1989) Rainforest Trees of Mainland South-Eastern Australia. Inkata Press, Sydney.
- Hauser, P.J. (1992) Fragments of Green, as identification guide for plants of the Greater Brisbane Region. Rainforest Conservation Society, Brisbane. [Reprinted from The Node, Newsletter of Brisbane Rainforest Action and Information Network, No. 13, September 1998]
From the "Bulletin", newsletter of the Queensland region of SGAP, March 2000.
Note re. Canthium vacciniifolium and C.microphyllum. These two species have recently been transferred to the genus Everistia (refer Reynolds, S.T. & Henderson, R.J.F. (1999). Austrobaileya 5(2):353-361). C.vacciniifolium is now Everistia vacciniifolia var vacciniifolia while C.microphyllum is Everistia vacciniifolia var nervosa.
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Australian Plants online - March 2002
Association of Societies for Growing Australian Plants
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