Category: Rainforest Trees

The Fuzzy Lemon Aspen (Acronychia vestita) is endemic to northeast Queensland occurring in upland wet sclerophyll forests and rainforest margins or disturbed areas from Kuranda to Paluma. It is generally a shrub to small tree but can grow up to 20m. The ovoid deep green leaves are simple with obvious lateral veins running at an angle from the mid-vein and then looping up before reaching the leaf margin.

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Flowering occurs from February-March and the fruit develop as globular fruit with a lumpy wrinked surface that turns from green to white or yellow when ripe.

This is not a particularly common tree around Paluma but there is a good example on the edge of Potters Park off Lennox Crescent that is currently bearing numerous developing fruit that should turn yellow in the next month or so.

The fruit are eaten by Cassowaries, Wompoo Fruit Doves and the Musky Rat-kangaroo. The leaves are one of several species eaten by the larvae of the Ulysses Butterfly.

Several other species of Acronychia including the Lemon Aspen (Acronychia acidula) are edible and used as a garnish or flavouring in drinks and chutney. A. vestita is noted as being edible in the original Rainforest Fruits book by Cooper & Cooper (1994) but I could not find any other references to edibility.

Text and photos (unless indicated) by Jamie Oliver

Gmelina dalyrympleana is a rainforest tree found in northeast Qld and Cape York as well as New Guinea. There are several species in this genus and most of them can be found in the wet tropics and share the common names White Beech, or Grey Teak). With its lovely pink flowers bright red fruit this species ranks as one of the more attractive in the genus.

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This tree is currently in fruit around Paluma and the bright red, oblong cherry-sized fruit are unmistakeable at several spots along the H-Track. The fruit might be mistaken for a Satin Ash at first glance but its seed capsule, which is bound tightly to the flesh of the fruit, is small and woody. The small pink flowers are occasional seen scattered on the ground on or next to the H-Track.

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The fruit is eaten by fruit pigeons. The tree can grow to 40m yields a course, but durable timber used for planks and floors. It is cultivated as an ornamental tree in Queensland and NSW.

Text and photos (unless indicated) by Jamie Oliver

This attractive rainforest tree, a member of the Myrtaceae family, has many common names, including, brush cherry, scrub cherry, creek lilly-pilly, creek satin-ash and watergum.  It grows mostly along water courses in rainforests and gallery forests at altitudes up to 1300 metres.

Worldwide, there are more than 1000 species of Syzygium ranging across PNG, the Pacific islands, Malaysia, SE Asia, India, Africa and Australia.  Australia has 57 species, with 47 of them in tropical Queensland.  Some species, easily recognisable are Paperbark satin-ash (Syzygium paparaceum with its purple fruit; Powder-puff lilly-pilly, (Syzygium wilsonii), with small purple fruit and a sub-species noted for its large magenta powder-puff flowers and lush creamy white fruit.

It is easy to understand how various Syzygium species, along with many other native Australian flowers, inspired May Gibbs to create her delightful bush babies.  Who could forget the movie magnate’s daughter, Lilly Pilly with her skirt, beret and muff made of lilly-pilly berries.

Although Syzygium australe can grow to 35 metres with a trunk diameter of 60 cm, it is a popular plant in ornamental gardens as it can be shaped and pruned into hedges. It is a fast-growing tree and can grow 2 metres in a year.

The ovate leaves are simple, opposite and approximately 30×100 x 10-40 mm.  Young leaves are bronze, turning to a deep, glossy green as they mature. They form dense foliage on this shapely tree.

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Flowering can occur at any time of year.  Flowers are clustered in axillary or terminal racemes. They are tiny, with white petals and numerous white stamens which give the flowers the appearance of delicate powder-puffs.  Flowering can be sparse, hiding amongst the leaves, or abundant, giving a dense cover of white.  Flowers are followed by a profusion of red fruit – berries.  These are 14-23 mm long with one or two seeds surrounded by crisp flesh similar to apple in texture. The fruit is edible, although can be tart.  It makes excellent jam and can be used as a base and flavouring for jellies, cakes and wine.

Some species of Syzygium were previously classified in the genus Acmena and others in the genus Eugenia.  The species known formerly as Eugenia Australis is now regarded as two separate species: Syzygium australe and Syzygium paniculatum.

There are many examples of Syzygium australe in Paluma.  A very old tree which usually bears fruit in profusion is outside No 75 Mount Spec Road, another, is outside the High Ropes course. Two more may be seen outside No 17 Mount Spec Road.

Text and photos (unless indicated) by Colwyn Campbell

The Atherton Fig (Ficus leptoclada) is one of 15 species of sandpaper fig in Australia. These figs are non-stranglers and have (to varying degrees) rough sandpapery leaves. Unlike the strangler figs, they are dioecious (having separate sexes).

Atherton Figs are endemic to northern Queensland rainforests up to an altitude of 1,000m. They are common on road sides or in regrowth areas where they grow as relatively small trees (up to 15m) with slender trunks. The leaves are eliptical to narrowly ovate and about 8-12 cm long with a raspy feel to the lips (yup – you are supposed to “kiss” the leaves to assist in identification!).

When in fruit, trees can be spectacularly laden in small brightly coloured fruit. Ripening figs show attractive shadings of yellow to orange-red and are born both on branchlets and on the main trunk or limbs. When ripe they are more uniformly red/purple and are up to 2cm in diameter.

The figs are eaten by fruit pigeons and the double-eyed fig parrot.

There is a lovely example of an Atherton Fig that is currently in fruit at the first small clearing about 100m down the walking track from McClelland’s lookout to Witt’s lookout. Look for coloured fruit on the ground. The tree has a narow trunk just behind a larger tree at the edge of the clearling looking back to McClelland’s lookout.

I have previously mentioned the close relationship between figs and the specialised wasp species that they rely on to pollinate their flowers. If you are interest in joining me in a deeper dive into the evolutionary biology of this relationship keep reading below (it might get a bit technical).

Text and photos by Jamie Oliver

https://apps.lucidcentral.org/rainforest/text/entities/ficus_leptoclada.htm

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Figs and Fig-wasps: an evolutionary arms race that may never end

Figs are not actually fruit (which develop from the ovary of a single flower) but rather an enclosed cluster of flowers (synconium). Since there are a variety of insects and other animals that enjoy munching on flowers, seeds and fruit, it makes some sense to enclose all your flowers in a tough leathery pouch, but then the problem is how to ensure polination of your flowers. Figs do this through associations with a family of wasps that specialize only on laying their eggs in the ovaries of figs. The relationship is highly specific: one fig-wasp species for each species of fig.

The basic sequence of polination and wasp reproduction is as follows. The female wasps are just small enought to enter the fig body through a small hole. In the process they lose their wings and antennae and will not subsequently be able to leave the fig. Once inside they lay their eggs in as many female flowers as possible and then die. The eggs then hatch out into male and female wasps. The males never leave the fig but spend their lives searching (and fighting other males) for newly hatched females to mate with. The last act of a male is to chew its way to the outside, making a large exit hole that allows new females to leave the fig. On their way out, the females collect pollen from male flowers, and then seek out new figs to lay their eggs in.

Wasps are notorious parasites and the fig wasps are no exception. Their main interest in the relationship is to produce as many offspring as possible by laying eggs in the ovaries of female flowers, where the larvae develop by eating the developing fig seeds and surrounding tissue. The destruction of any developing seeds is clearly not in the best interests of the fig, so the relationship is a tense one: the fig just wants to use the wasp to tranport pollen from the male flowers to the female flowers (in a different fig), while the wasps, given a chance, would lay their eggs in all or most of the ovaries of female flowers, rendering them (and potentiallly the whole tree) sterile in the process. Thus while each species is dependent on the other, they are both trying to gain the upper hand with the evolution of traits that maximise the advantage on both sides. In effect this is an evolutionary “arms race”.

In hermaphroditic figs, where the separate male and female flowers reside in the same fig body, the solution that has evolved in the fig species is to make some of the female flowers inaccessible by hiding them deep under the inner surface of the fig where the wasp’s ovipositor can’t reach, while letting the wasp parasitise the other flowers so as to ensure some wasps are allowed to develop. This compromise lets some of the fig flowers develop fully mature seeds, but many are sacrificed to allow wasps to developed. The wasp on the other hand has lower than optimal reproduction since it can’t parasitse every female flower. This has turned into a relatively stable stand-off between the competing interests of the two species. However ….

In dioecious species (thought to have evolved from hermaphroditic speces) there are trees with figs that are all male, and other trees that are all female. In these species the balance may have shifted a bit in favour of the figs. In this case the male trees have male flowers but also female flowers that are sterile (the figs are more accurately described as “functionally” male). As per the above sequence, female wasps enter male figs and lay their eggs in the sterile female flowers. The offspring hatch out and the new fertilised females collect pollen from the fully functional male flowers as they exit the fig to find other fruit to parasitise.

The twist here is that the female fig trees have fruit (with only fully fertile female flowers) that are equally attractive to the female wasps (they are drawn in by a specific odour emited by the fig) but the ovaries in these female flowers are completely inaccessible to the wasp. So female wasps that end up entering a female fig wander around inside polinating the female flowers but never managing to parasitise any flowers before they die. This arrangement suits these fig species well since it can invest as much energy as it wants into the development of female flowers and seeds and only sacrifice a smaller amount of energy into the production of sterile female flowers in the male figs.

Since a small amount of pollen can fertilise a large number of female flowers there are often many more female figs compared to male. The female figs don’t get parasitised so the result is a high reproductive output for the figs. But if the majority of figs in any location are female ones, then the wasps lose out since most of the female wasps will end up in female figs and never reproduce. The fig species only needs to produce enough male figs to ensure adequate pollen production and sufficient wasp production to ensure the pollen is duly transported to all the female figs. At this point if you have been following the story you may (like me) think that its starting to look like the fig is “farming” wasps for the purpose of polination! Perhaps future evolution will see wasps being more and more like a managed speces. But since evolution is based on the accumulation of chance events, perhaps wasps will evolve countermeasures that enable it to parasitise female fig flowers, or avoid them in favour of male figs ….. and the “arms race” will continue.

Jamie Oliver

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Further Reading:

https://www2.palomar.edu/users/warmstrong/dawkins.htm#dioecy
https://link.springer.com/article/10.1007/BF01975678
https://onlinelibrary.wiley.com/doi/10.1034/j.1600-0706.2003.12212.x
https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1420-9101.1995.8030301.x

It seems appropriate that during this month of Christmas we feature an evergreen conifer as our tree of the month. The Black Pine (Prumnopitys amara). This species is widely distributed in north-east Queensland as well as New Guinea and Indonesia. It can grow to 60m and has a frequently dark to blackish trunk with scattered cracks. Mature leaves are long and narrow with a distinct groove along the mid-vein on the upper surface. The species name “amara” is from the latin word for bitter and refers to the fact that the leaves, if chewed, are initially sweet tasting but then turn bitter.

None of these features are easy to distinguish in the field, but luckily the fruit are very easily recognised scattered on the ground along walking tracks. They are bright red and globular (20-25mm wide) with a shallow flesh around a hard gloubular seed. Fruit can be found on the forest floor from December to February. They are eaten by Cassowaries, and several species of rainforest rat.

Black Pine nuts are one of about four species of rainforest seeds regularly that were used (and relied on) on by rainforest aborigines as a source of carbohydrates. While some of the seeds required lengthy preparation to leach out toxins and bitter chemicals, Black Pine seeds, could simply be collected and cooked for thiry minutes in a grond oven and then cracked open to reveal the tasty kernels which were then pulverised between two stones.

The timber from the Black Pine is used in New Guinea and Indonesia for general building purposes as well as funiture including butter churns.

Other conifers around Paluma

Conifers belong to a group of seed-bearing plants (including Cycads and Ginkos) in which the seed is not enclosed in and ovary (Gymnosperms – meaning naked seed). The seeds of conifers (Pines and relatives) are borne within cones. Australia has several conifers that are endemic (found only in Australia) and one which is considered to be a “living fossil” (Wollemi Pine).

The Black Pine is one of only a few naturally occurring rainforest conifers in the Paluma region. Two others that can be potentially (but not commonly) seen are “Plum Pines” or Podocarps (Podocarpus grayae and Podocarpus elatus). Both are called Brown Pine and both are endemic to Australia. While not strictly a rainforest pine the Hoop Pine (Araucaria cunninghami) can also be seen naturally on the slopes down to the coast along the range road, and there are several large specimens that have been planted out around the village. It is not restricted to rainforests, and is common around the rocky coast of Magnetic Island.

There are other species of native pine that don’t naturally occur in Paluma but that have been planted out around the village. These include a small Bunya Pine (Araucaria bidwilli) around the first corner of Smith Crescent and a Kauri pine (probably Agathis microstachya*) behind the Paluma Environmental Education Centre. Two small potted native “Christmas trees” adjacent to the the Community hall include one conifer naturally found only in the mountains west of Mossman (Mt Spurgeon pine, Prumnopitys ladei) and a variety of casuarina (not a conifer) called the Daintree Pine (Gymnostroma australianum).

Text and photos (unless indicated) by Jamie Oliver

*Note: the Kauri pine behind PEEC is, on closer inspection, most likely to be Agathis robusta. It is distinguised by its smooth bark with thin flakes. – Jamie

The washing-board tree (Cryptocarya corrugata) belongs to the Laurel family (Lauracea). There are over 300 species in the genus Cryptocarya, most of which inhabit cloud covered rainforests. This particular species is endemic to central and northern Queensland upland rainforests.

On close inspection the tree has distinctive red flakey bark and conspicuous fist to saucer-sized dimples along its trunk where the bark has flaked off. The sap-wood has a corrugataed surface, but this is largely masked by the outer bark.

The washing-board tree can grow up to 35m tall and occasionally has a butressed trunk. The cut bark and outer wood (a blaze) smells like sugar cane, but with alternative common names such as Bull’s Breath and Acid Wood this smell be a matter of personal perception.

The twigs and new leaves are covered in twisted brown hairs, while the older leaves become hairless (glabrous) with age

The fruit of the Washing-board tree are also distinctive. They are large ( 15-22mm high x 22-34mm wide) and broad or bilobed with a smooth to shiny purple-black outer surface. Flowering occurs in December, with mature fruit developing the following September. The fruit are eaten by cassowaries and fruit doves.

The wood of the washing board tree is infrequently used for general purpose timber under the name “Corduory Laurel.

You can find a tagged specimen (#4) of this species near the beginning of the H-Track (starting at Whalley Cr) on the right hand side of the track. This tree is part of a Guide to the Trees of the H-Track which is currently being revised with new text and new white tags.

Text by Jamie Oliver

Also known as Powder-puff Lilly Pilly and Wilson’s Satinash, this tree was possibly named after Dr Thomas Braidwood Wilson, (1792 – 1843), a botanical collector in the 1890’s.

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It is an unremarkable-looking little tree, with its straggly growth under and among the protective foliage of neighbouring trees, but it bears beautiful, pompon flowers which make the plant worthy of recognition.  Although not endemic to Paluma, there are several examples of this Lilly Pilly in Paluma gardens.  Perhaps the most striking, as it is bearing blooms at present, is in the garden bed beside the office at PEEC.  Another small shrub grows in the Trees of Memory grove, alongside the memorial stone.

The natural distribution for this Lilly Pilly is in the rainforest at Whyanbeel, near Mossman to Hinchinbrook Island, at altitudes up to 850 metres.

The leaves of this tree are distinctive.  They are simple, alternate or opposite, hairless and can be quite large, growing from 80 – 190 mm by 22 -54 mm. with a recurved margin.  New growth is spectacular with deep salmon-pink colouration.

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Flowers, growing in axillary or terminal panicles, hang modestly among the foliage and can easily be missed.   The individual flowers are tiny, the red trumpet shaped calyx hidden by the dense cluster of magenta to crimson stamens, about 20 mm in length.  They form a dense, soft pompon about the size of a mandarin, hence the name powder-puff.  An accompanying photo shows the remains of the flower panicle after the stamens have gone. Flowering season can last from June to December.

The fruit of the Powder-puff Lilly Pilly is a fleshy white or cream berry, 10-18 mm long by 10 -16 mm long.  It contains one seed. Like most Syzygiums, the fruit is edible but is very sour and unpleasant to eat raw.  As I do not have a photo of the fruit, a sketch will have to suffice.  Note the ant which was determined to get into the picture!

Next time you stroll around the streets of Paluma, see if you can spot one of these demure little trees.

Text and photos by Colwyn Campbell

Strangler figs are one of the distinctive features of rainforests. They start life as epiphytes half-way up the forest canopy, germinating from seeds in bird or bat droppings that have landed on a suitable tree branch. The young seedling sends roots sinuously down the trunk of the host tree while growing its branches up towards the forest canopy. As light severely limits the growth rates of tree seedlings on the forest floor, strangler figs gain a huge advantage by starting off life near the canopy courtesy of its host tree. Once the fig’s roots reach the ground they penetrate the soil where the added supply of nutrients and water spurs rapid growth of both the branches and aerial (above-ground) roots, which progessively envelop the host tree.

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Seedlings can also occasionally germinate on large boulders, cliff faces and even old ruins (e.g. the ruins around Anchor Wat in Cambodia). The height at which the seedling germinates, as well as the orientation of the host dictates how the roots will grow. If a tree with a strangler on it is knocked over into a diagonal growth position, the roots will start to grow vertically directly down to the ground. An impressive example of this diagonal growth with vertical roots can be found on the famous Curtain Fig Tree outside Yungaburra in the Tablelands.

Mature figs often either kill or out-live their host, leaving a hollow core in the network of thick roots that make up the trunk of many mature stranger figs. The cause of host death is not certain and while the name suggests that the roots eventually strangle the host trunk, hosts will also have to compete with the fig for canopy space and nutrients and water in the surrounding soil and this could severly weaken the host tree. However a recent recent study of trees that survived Cyclone Yasi suggests that stranglers may actual help their hosts survive these extreme storms, perhaps by adding structural support to their host in the face of cyclonic winds.

Mature stranger figs reach enourmous size and can dominate the canopy. There are several huge figs at the bottom of Bambaroo track (unknown species) which can be seen on the satellite view of Google Earth and have canopies exceeding 50m in diameter. The largest tree in the world (in terms of area covered) is a Banyan fig (also a strangler) that covers a massive 4 acres.

Figs belong the Family Morace, and the group known as stranglers (starting off as epiphytes on a host tree or rock) belong to the subsection Urostigma. There are around 1,000 species of Ficus worldwide and Australian rainforests host about 40 species. Of these, 18 are stranglers.

Ficus watkinsiana is one of several species of strangler figs that occur around Paluma. A good example can be found on the Paluma “Rainforest Track” opposite Smith Crescent. This specimen has a dedicated platform in front of it, including an extension that allow photographers to step back so that they can get most of the tree in a photo.

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Identification of figs is not easy and professional taxonomists may even resort to electron microscope imagery to detect minute differences in the strucuture of the fruit to confirm identification. However, based on distribution records, leaf size and fruit shape/size I am pretty confident that this one is indeed F. watkinsiana. Other species of strangler that have been identified on the H-track are F. destruens and F. obliqua. F. destruens has similar leaves but the fruit, while similar in shape are significantly smaller than F. watkinsiana. Along the H-track, starting from the JCU house, there are two specimens of F. destruens labelled with white tags (numbers 2 and 7). F. obliqua can be identified from its small globular organge coloured fruit. There is a specimen about 20m from the first right hand bend of the H-track starting from Lennox Crescent on the left side of the track.

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While strangler figs have a fascinating growth habit, all figs also exhibit amazing and bizarre reproductive characteristics that would require a separate post to describe in full. One fact worth noting is that almost every species of fig is dependent on a single species of tiny wasp for pollination! A scary fact since all it would take is the extinction of one species of insect to wipe out an entire species of majestic fig trees! We usually think of insects as ubiquitous and prolific, but a recent scientific global survey found that 40% of all insect species are declining and that a third are endangered.

For our local Ficus watkinsiana the polinating wasp is Pleistodontes nigriventris. You may never see one ( I couldn’t find a picture of it on the web) but you would certainly know if it went extinct!

Text and photos (unless indicated) by Jamie Oliver