Friday, July 26, 2013


Acmena smithii (Syzygium smithii)
This is one of our showiest local native trees. Found in the dry rainforests along the range, it looks spectacular at this time of year when it is laden with purplish pink fruits.

In garden situations, it becomes a medium sized tree (8-10 metres) though it can grow much larger in its native rainforest.  It has dense foliage which (unless trimmed) extends to the ground, making it a good screen plant.
For this purpose it  can be left to grow naturally, or trimmed to make a  large, quick-growing hedge, with flushes of new red leaves stimulated by trimming. In either case, it is a very attractive garden plant.
It has been claimed that it resists frosts to to -7°C (or more). I have some doubts about the frost hardiness of small specimens, and would want to be protecting them in winter if harsh frosts are expected, until they were at least a metre high. This only takes only a year or two.

Acmena smithii is the drought hardiest of Australia's lillypillies.

Acmena or Syzygium?
Botanists have not come to an agreement about the name of this plant. All our lillypillies, of both Acmena and Syzygium species, were once grouped together under the name "Eugenia". Then in the 1930s they were split off from that genus and given their new names. This left only one Australian Eugenia species (and some 1000 overseas ones) behind.
Recently, there has been a move to put Acmena back together with Syzygium, which would give this plant the name "Syzygium smithii". Not everyone agrees, however. Botanists often disagree about whether similar plants are different enough to warrant being split up under two or more names, or whether their similarities justify lumping them together. In this case, we have lumpers in some states (and federally), who now use Syzygium smithii, and splitters sticking to their guns and "Acmena smithii" in Queensland and New South Wales.

We amateurs can certainly see clear differences between the two genera, so find the split convenient.
The fruit of Acmena has a neat circular cup at the apex of the fruit (the end opposite the stalk).

Here it is (above) on Acmena smithii...

...and on Acmena ingens, our two local Acmena species.

Syzygium fruit has this cup obscured by little fleshy claws - actually the remnants of the flower calyx.

Here they are (above) on Syzygium paniculatum, a species from the Sydney area growing in my garden...

... on Syzygium australe, photographed in the Bunya Mountains,

and somewhat less obviously on these Syzygium crebrinerve, from Goomburra.

The seeds are different, too.
 The flesh clings very firmly to the seeds of Acmena species (above), and is hard to get off without damaging the rather soft seed. (Fortunately, for those who like to "flesh" seeds before planting them, Acmena smithii doesn't need this treatment, and grows well when planted which the fruit whole.)

Syzygium seeds  sit quite loosely in the crisp white flesh, and are easy to pick out. Above is Syzygium australe...

 ...and this is Syzygium paniculatum.

A third rather similar fruit is that of the satinwood (above), Vitex lignum-vitae. It is sometimes mistaken for a lillypilly, but is easy to distinguish because there's nothing special about the apex of the fruit. Notice also that the white flesh discolours very quickly, like that of an apple.

Acmena and Syzygium can be distinguished from each other by their flowers, too.

Syzygium species (above) have large, fluffy flowers. May Gibbs used them as the inspiration for the delightful Miss Lilly Pilly, the famous movie star who meets Snugglepot and Cuddlepie.

Acmena flowers are rather boring by comparison.

Thursday, July 18, 2013

Sandfly Zieria

Zieria smithii
(pronounced ZEE-AREA)

I photographed this rather delicate-looking shrub growing wild in the Pechey arboretum, a few weeks ago. It’s not common in our area, but is also known from the rather sandy soil around Kleinton, north of Highfields.
It’s an unmistakable plant, the only shrub hereabouts with these distinctive triple leaves. We see it as a metre-high plant, but in north Queensland it can apparently get to 6 metres.
It is rather pretty, with its tiny four-petalled flowers coming out at this time of year when flowering plants are a little harder to find. It would probably appreciate being pruned quite hard after flowering, to keep in neatly shaped.
Its rather odd name refers to a belief that rubbing the aromatic leaves on the skin repels sandflies and mosquitos . I have no idea whether it works. You will smell interesting, though. Some people think it smells like kerosene. Others liken it to turmeric.

Thursday, July 11, 2013

Square Stemmed Broom

Spartothamnella juncea
  This plant looks spectacular at this time of year, with its little orange fruits showing us why the plant has the alternative common name of “bead bush”.

It usually grows about a metre high, and about half a metre in diameter. Grown as a neat, free-standing plant, it tends to be somewhat shapeless, as seen with this plant at Peacehaven Botanic Park. Pruning (after the fruits finish in August or September) neatens up its shape and encourages fresh green growth.
New growth in early summer comes with masses of little white flowers.
This is a very tolerant plant, found on drought-prone, well-drained blacksoil or sandstone hillsides, and in situations where it gets wet feet from time to time. It does like mulch, and if the season is very dry, it looks its best if given some water during the spring growth period.
It does well in full sun or semi-shade.
Its habitat has often been invaded by lantana and it makes a good replacement plant in areas where that weedy invader is being cleared, offering the birds some similar resources in the way of nesting sites and crops of small fruits.
Close planted, square-stemmed broom plants make effective hedges, and can be used in sites such as under eaves.
I noticed some healthy little plants for sale in Crows Nest Community Nursery when I was there last week.

Saturday, July 6, 2013

Common Tussock Grass

Poa labillardierei 

Common Tussock Grass in summer, at the Bunya Mountains
“Poa” was the ancient Greek word for “fodder”. Nor surprisingly, most Poa species are important pasture grasses.
Poa is one of the oldest scientific plant names still in use, first given to a common European grass (Poa annua) in 1753 by Linnaeus, in his famous work “Species Plantarum” – the publication which began the modern system of plant names. There are now about 500 Poa species known, around the world They are so representative of “typical grass” that they have given the grass family,  Poaceae its name.

Our local species are attractive grasses which form dense, knee-high, weeping tussocks. Their graceful purplish flowerheads mature into conspicuous white seedheads, giving them the alternative common name “whitetop”.

This grass is seen to best advantage on the “balds” in the Bunya mountains, where it is the dominant grass.

The balds are appealing grassy patches sprinkled throughout the rainforest. They were originally maintained by aboriginal burning, to create “kangaroo grounds” for hunting. These remnants of Australia's cultural heritage are now slowly being invaded with weeds - although the National Park staff hope to reverse the process by learning and implementing a suitable fire regime.

This grass is probably the major host plant for the Banks’ brown butterfly (Heteronympha banksii mariposa), a beautifully patterned butterfly which spends most of its long adult life (it breeds only once a year) in the rainforest understorey.
Poa grasses were used by aborigines for making nets and string dilly bags.