Pandanus species of the Wet Tropics of Queensland, Australia

1. P. brookei (Martelli)
2. P. cookii (Martelli)
3. P. dammannii (Warb.)
4. P. gemmifer (St. John)
5. P. lauterbachii (Schum. & Warb.)
6. P. monticola (Muell.)
7. P. solms-laubachii (Muell.)
8. P. tectorius (Parkinson)
9. P. sp. unknown



Pandanus brookei - no info



Pandanus cookii
Pandanus cookii
Photo supplied by John Beasley, taken above Davies Creek Falls.

JB says "There are short prop roots at the base, not visible in the photo, and the fruit (Nov-Mar) are orange-red, a bit like gemmifer."



Pandanus dammannii
synonyms : P. arnhemensis (St. John), P. medialinermis (St. John), P. orbicularis (St. John), P. stolonifer (St. John)


Pandanus gemmifer

Pandanus gemmifer bulbils
J. Wrigley, ANBG
Pandanus gemmifer fruit
J. Wrigley, ANBG
From "Encyclopaedia of Australian plants suitable for cultivation, volume 7",
by Rodger Elliot and David Jones, published by Lothian Press :
Grows in highland rainforest on the edge of lakes and streams.
The tree produces plantlets (bulbils) on the trunk which fall to the ground and take root, forming thickets.
The spiral direction of the leaves becomes reversed after each flowering.




Pandanus lauterbachii

This image is archived from
"A Field Guide to Pandanus in New Guinea, The Bismark Archipelago and the Solomon Islands"
by Matthew Jebb (National Botanic Gardens of Ireland)
Pandanus lauterbachii from A Field Guide to Pandanus in New Guinea, The Bismark Archipelago and the Solomon Islands
P. lauterbachii is also known to inhabit Cape York, including the swampy rainforest areas around springs in the Wenlock Basin.



Pandanus monticola
synonym : P. pluvisilvaticus (St. John)

Pandanus monticola Pandanus monticola is restricted to the reduced light conditions of the rainforest. P. monticola has shorter, narrower leaves than P. solms-laubachii, that are arranged on their stem over the top metre or so, pointing upwards at 45° to start off with.

The stems are narrow, about 3 cm diameter, and are unable to keep the plant upright, so they sprawl in a tangle with vines and each other. When the barbed leaves from two stems interlock, they form an impenetrable barrier.


Pandanus monticola trunk Pandanus monticola trunk in section

Pandanus monticola male inflorescence Pandanus monticola male inflorescence

Pandanus monticola male inflorescence
Pandanus monticola male inflorescence They have male and female flowers on different plants (dioecious). The male inflorescence, below, is about 60 cm long, with large white bracts that have an unusual "off" scent that attracts flies.

The female flowers have a stem about 10 cm long.

Pandanus monticola female early fruit The female flower is well-protected within the enfolded thorny leaves and the early fruit swells quickly, until the stalk lengthens and the mature fruit hangs free.

Pandanus monticola catkin This is a close-up of the male "catkin" showing the individual stamens.

Pandanus monticola fruit Pandanus monticola cut fruit The fruits are large and prickly and are a favourite of the Sulphur-crested Cockatoo, that rips off a chunk and then scatters most of the pieces across the forest floor.

Pandanus monticola fruit piece



Pandanus solms-laubachii
synonyms (all St. John) : P. citraceus, P. kurandensis, P. mossmanicus, P. papillosus, P. punctatus, P. radicifer, P. rivularis

Pandanus solms-laubachii juvenile Notice how the leaves seem to radiate out from the growing apex in a hemisphere, and how thick the trunk is immediately below the apex.

Where the old leaves have fallen away, the exposed trunk shows leaf scars and is otherwise smooth and shiney. But further down the bark becomes dimpled and then it develops "prongs" which are brittle, woody spikes up to 7 cm long, with some hooked thorns that grow vertically close to the bark. This surface is a good place for spiders' webs and trapped leaves, debris, moss, epiphytes and lichens.

(Lichens are the combination of an alga embedded in a fungus. This association is mutually beneficial - the alga gains protection from drying out, and the fungus absorbs some of the sugars the alga produces by photosynthesis.)

The base of the trunk is supported by prop roots, but in this species they are not well-developed. Sometimes these trees grow to 10 metres without branching, but it is much more common that they divide into two or three branches, that may themselves divide again. The angles that the branches make have an primitive "un-natural" look about them.


Pandanus solms-laubachii mature Pandanus solms-laubachii bark with lichens

Pandanus solms-laubachii female flower The species is dioecious, meaning each plant is either male or female.
This is a female inflorescence, or compound flower, which will develop into the fruit.
The three leaves surrounding the flower are lacking chlorophyll in their lower halves.
The bracts that surround the flowers are white and release an 'off' smell that attracts flies, presumably they bring pollen from a nearby males to fertilise the flower.


Pandanus solms-laubachii compound fruit 2 The developing fruit has a pineapple shape, but at maturation the core swells up and the shape becomes round as the segments pop-off.

Pandanus solms-laubachii fruit section

The central core has a texture like wet paper maché.

Pandanus solms-laubachii 
unfertilised female flower When the segments have fallen away, the stalk and core of the fruit hangs from the stem for many months.

Pandanus solms-laubachii compound fruit Pandanus solms-laubachii prong on bark Pandanus solms-laubachii fruit segments

Pandanus solms-laubachii 
cut fruit showing edible flesh When the fruit is freshly fallen, the base of the fruit segment has some firm, fibrous flesh that can be sliced away and eaten. It has an aromatic smell and a peppery taste that is best swallowed quickly. I cannot guarantee that you won't get a stomach upset from this.

Pandanus solms-laubachii showing fruit segment in section
After a few hours sweating under a summer sun, the fruits start to ferment and the smell attracts butterflies and bees. Within a couple of days, all the flesh has been removed, leaving a stump of stiff fibres.

Pandanus solms-laubachii showing locule Pandanus solms-laubachii showing empty locule The fruits are compound with about 100 segments (phalanges) forming one pineapple-like fruiting body, with each segment having 7 to 15 chambers. Each chamber is a narrow tube in the central woody core, where the seed forms, and a hollow woody extension which acts as a bouyancy support.

Pandanus solms-laubachii segments floating

Pandanus solms-laubachii segment section
Pandanus solms-laubachii seeds
In about half of the segments that I have opened, there are 1 or 2 chambers with an oily seed in them.


Pandanus solms-laubachii leaf 4.13 metres The longest leaves come from the unbranched trees. I measured this leaf to be 4.13 metres and its fine tip was already broken off.

The leaf has parallel veins with thorns mounted on the two leaf edges and also on the underneath side of the mid-rib in the upper half.

Pandanus solms-laubachii dried leaf section The leaf section is deeply channelled, giving the leaf stiffness. But when it collapses, it usually stays collapsed, giving the typical 'Pandanus' look.


Two long, flat strips can be easily cut from the edges of the leaf with a sharp blade. The thorns on the margin can also easily be cut away, leaving strips that can be dried and woven or used as string.

Pandanus solms-laubachii leaf thorns Thorns are much heavier on the margins near the base, where they are well-placed to catch falling debris. I do not know how this could help the plant.

Pandanus solms-laubachii section through leaf bases The leaves clasp the stem and are set somewhat over 120° apart, giving the arrangement of three leaves that form 3 spirals. This gives the species its common name of "Screw Pine", although this is a flowering plant, not a true pine.

Pandanus solms-laubachii showing fruit scar, buds and leaf scars The fruit is large and quite heavy, so it needs a strong stalk to hold and feed it. When the old stalk falls away it leaves a socket, and two buds (?) sometimes form there. These sockets are approximately 140 mm apart, and perhaps represent a year's growth.

Pandanus solms-laubachii axial bud Notice the leaf scars. At the middle of each scar there is a triangular feature that is presumably an axial bud , and these develop in size as the branch matures, forming three spirals up the branch. At each fruiting point, the handedness of the spirals reverses itself, as also noted for P. gemmifer.

Branched trees can have different handed spirals simultaneously.




Pandanus tectorius
synonym : P. pedunculatus

Pandanus tectorius fruit
A. McWhirter,
ANBG

Pandanus tectorius phalange Pandanus tectorius phalange in section Pandanus tectorius kernel

The kernels taste OK, and are said to be very nutritious, but they weigh only about 0.1 gm each.


Unknown Pandanus sp.

Pandanus sp.
This unidentified species is similar to P. solms-laubachii, but the leaves are not crowded at the end of the trunk, and they show a distinct spiral arrangement that forms a triple helix around the trunk.

Since the plants are dioecious, it is possible there is sexual dimorphism. Could this be just the male of the species ?

Pandanus sp. showing thorns on leaf
The thorns are much heavier and set more aggressively than P. solms-laubachii. The leaf on the underneath side of the mid-rib carries thorns in its lower half, and these point back towards the base. In the upper part, the mid-rib has thorns point towards the tip as in P. solms-laubachii.

Pandanus sp. showing spiral arrangement The arrangement of thorns makes the plant particularly good at catching debris.

Pandanus solms-laubachii showing prop roots Pandanus sp. showing prop roots P. solms-laubachii (left) has prop roots crowded around the base, while this species (right) has prop roots in an open formation reaching 900mm up the trunk. Sometimes the main trunk is only very thin at the base.

The bark does not have 'prongs' like P. solms-laubachii, but has lenticels(?) like P. tectorius .

Pandanus sp. bark

Pandanus sp. showing upper trunk This 10m tall specimen was snapped off during Cyclone Larry.