Tuesday, 31 March 2015

Casuarina cones

Casuarinas are quintessentially Australian to most Australians. Perhaps not to the same degree as eucalypts and acacias, but they are certainly a key component of the Australian flora and psyche. From the whispering river-oaks of inland water courses, to the beach-delimiting she-oaks of various kinds, to the inland bull-oaks or bulokes of the Murray-Darling.

River oaks, Casuarina cunninhamiana, along the Abercrombie River in central New South Wales.

Coastal she-oak, or beach casuarina, Casuarina equisetifolia ssp incana growing on beach sand on Lady Musgrave Island in the Great Barrier Reef (see Heron & Lady Musgrave Islands post).

Casuarinas belong to the Family Casuarinaceae. For a long time this family was considered to be fairly primitive within the dicotyledonous plants, and was placed pretty much out on its own, often being put in its own Order (major grouping of plants). But more recent work indicates it actually fits within the Order Fagales, which includes birches, aspens and hazels (Betulaceae), oaks and beeches (Fagaceae), the Gondwanan southern beeches (Nothofagaceae), walnuts, pecans and hickory (Juglandaceae) and a couple of other small related families). Casuarinaceae is thought to be most closely related to Betulaceae.

This placement might seem odd to the casual observer, (I was certainly rather surprised when I looked into it) but they are characterised by having separate male and female flowers, the male flowers often being in the form of catkins, and are wind-pollinated.

The silver birch, Betula pendula, doesn't bear any immediate resemblance to casuarinas!

The Casuarinaceae are distributed essentially throughout Malesia, Australia, and into the south-west Pacific, with a few outliers further afield. And there are a lot of introduced plantings around the globe, particularly in coastal situations. There are considered to be just under 100 species, with 65 occurring in Australia. Originally, all species were within the genus Casuarina, but they have recently been split amongst four genera, the majority in Allocasuarina (61 species) and Casuarina (17 species). But I doubt any one is likely to start using anything but casuarina as the common name for most members of the group (the other two genera are Gymnostoma and Ceuthostoma).

Apart from the immediately distinctive needle-like foliage (which isn’t actually foliage but photosynthetic branchlets – the leaves are reduced to whorls of tiny scale-like teeth), the fruits are also characteristic, being cone-like, and generally referred to as cones, although technically they are woody infructescences. While superficially all rather similar in form, the details of the cones do vary a fair bit. And so finally we get to what this post is about – basically just a gallery of photos of the cones of some of the local casuarina species.

River oak or River she-oak  Casuarina cunninghamiana
This is one of the most common of the casuarinas around Canberra and apart from occurring naturally along the local river courses, it is also planted extensively as a landscape tree.

Young developing cones with dried off styles of the withered 'flowers' still adhering

The flowers/cones frequently develop as terminal or sub-terminal clusters

Early stage cone of Casuarina cunninghamiana

Immature cones along a branchlet

A tight cluster of mature cones, but mostly not yet opened to release their seeds

Drooping She-oak  Allocasuarina verticillata (prev. C. stricta)
This is another species that occurs commonly in Canberra, but is generally more restricted to grassy woodlands and rocky hillsides. In contrast to the cones of C. cunninghamiana which are really quite small, the cones of A. verticillata are large and chunky.

Developing cone of the drooping she-oak Allocasuarina verticillata

The stalk or peduncle is often quite short, the cone sometimes appearing to grow straight out of the branch

Mature, partly opened cones of drooping she-oak

Old cones often persist on the tree for years - this one supporting lichen growth

Black she-oak  Allocasuarina littoralis
Although the specific name littoralis indicates a coastal distribution, the black she-oak also grows well inland. Nevertheless, the following photos were taken at Narooma on the New South Wales south coast.

Young developing cone of the black she-oak

Cluster of three developing black she-oak cones in early morning sunlight

Mature cones of black she-oak showing characteristic shape

Allocasuarina distyla
For some reason, this species doesn't have an accepted common name, despite it having by far the most attractive cones of the four species included in this post. It occurs in Sydney sandstone areas, particularly in heathland associations. These photos were taken at Currarong near Jervis Bay.

Allocasuarina distyla - flower head developing into a cone

Cluster of three young developing Allocasuarina distyla cones

Developing Allocasuarina distyla cone

Rich colours of a develoiping Allocasuarina distyla cone.
The pointed end (due to sterile apical flowers) is fairly characteristic of this species.

Mature but unopened cone of Allocasuarina distyla

Allocasuarina distyla cone fully opened and seeds released

One final point on leaving – the name casuarina derives from a Malay word, kasuari, which means cassowary, in allusion to the supposed similarity between the tree’s foliage and the bird's plumage. And the equisetifolia part of the scientific name of the coastal she-oak Casuarina equisetifolia, comes from the Latin, equisetum, meaning horse hair, this time in reference to the resemblance of the drooping foliage to a horse's tail. Hmmm!

See earlier post -  Missy - for the story of this semi-tame cassowary


  1. An interesting post - particularly re the name!

    1. I do like an egregiously esoteric etymology...

  2. Harevy

    I am intrigued why you haven't included Allocasuarina nana. It is a very low plant (thus 'nana') which forms dense heaths in areas not too far from Canberra (eg around the Big Hole in Deua NP and just North of Mongarlowe.

    1. Martin, there are several other 'local' species that could have been included, but the reason I didn't is really quite simple - I don't have photos of them! (yet). Apart from nana, these might include paludosa (swamp she-oak), torulosa (forest oak), and diminuta.

    2. And now I think of it, there are leuhmannii and diminuta out around Weddin Mountain where we do our banding, so now you've set me a challenge...

    3. You have also set a challenge for me and I think I am starting from a position worse off than you for both images and identification skills!


  3. Congratulations on your great pics of the she-oaks, Harvey. Karen Wilson