Autumn colour, and Sassafras seeds

This long balmy autumn is drawing to a close. But it has given us some remarkable sights.

Although not exactly spectacular, this is at least "impressive". I cannot begin to calculate the vast number of seeds of the Sassafras trees (Doryphora sassafras) which are lying on the ground here. As I have mentioned, in the context of house painting and wind, these seeds have been flying around my house for several weeks now. Some have simply dropped from the trees, and are lying here, awaiting a good rain storm to flatten them down to the ground. Without that soil contact they have close to zero chance of germination.
Now if Peter Garrett had seen these seeds lying here, he might have thought of using them as insulation in house roofs. They certainly look fluffy enough to do that job.

I just jammed my boot in amongst the seeds,
to show their depth.

To give you a better idea of the numbers of seeds involved in just those few images, here is a close up of a single intact Sassafras seed. It is on a blue woollen jumper, so the coarse knitting pattern will give you some idea of scale. The seed itself is about the size of a match-head, and the hairy appendages are somewhere between a 5 cent coin and a 10 cent coin in area (if flattened). The seed appendages are the method of dispersal, for the plant, when it seeds. The seeds catch the wind very successfully, when the seed capsules on the tree open, or when the entire seed capsule falls to the ground. Obviously they fly best when caught by the wind from high in a Sassafras tree. They have been floating around everywhere at my place for the last three weeks now. There is hardly anywhere which is free of these intrusive flying seeds.

Cool climate gardeners tend to associate autumn with coloured leaves. My Ornamental Pistachio, Pistacio sinensis, was just reaching its peak last week when the wind blew all its leaves away.

My neighbours tree has been looking great,

when glimpsed through evergreen trees.And my own Acer rubrum "October Glory" is looking fine, growing on the west side of the house, to show the sunlight through the leaves. It is one of Fleming's Nurseries "Lipstick range" of colourful autumn trees.

These are the brightest leaves I have at present. Not as colourful as plants I was familiar with in Canberra, but the trade-off is that biting cold weather which helps produce the bright colours. Frankly, I do not miss severe frosts.

Sassafras flowers - a detailed presentation

Sassafras flowers are blossoming all over Robertson at present. I mentioned them coming into flower, last week. I am still not able to bring you the sensation of their sweet perfume, unfortunately.At the time I wanted to go into some detail of the strange structure of the flower, but I could not find out enough information to enable me to explain them to you. Tonight I think I am ready to try.
Kindly bear with me, dear reader. I have never before seen any flower with the structure which you are about to see.

Sassafras flowers develop in threes.
One single flower in the centre,
and two buds which will develop as the first flower fades.

Here is a single flower - cropped.
It is about the size of a small thimble
just large enough to take my little finger.
Note the circle of thin stamens.
Each stamen has a pair of prominent white swellings at the base.
As I shall explain later, those swellings are the anthers,
but the pollen within them is not yet ripe - not ready to be dispersed.

Another flower - picked, and ready for dissection.

Here is how the flower (inflorescence) is described by botanists. This is sourced from "Forest Trees of Australia". Click to enlarge image so you can read the text.
The dissection commences. I have removed several petals ("perianth lobes") so you can see into the flower, from the side view. Note the fine needle-like structures which are the stamens of the flower.
Click to enlarge the image. Note the fine downy hairs on the petal surface and on the outside of the swollen base of the flower (ovary capsule). It is this part of the flower which swells into the seed capsule, and from my memory of the previous seeding explosion 3 years ago, those seed capsules are noticeably hairy as they develop. In fact their hairiness is significant, for the seeds are wind dispersed, and anything which helps catch the wind is important to successful seed dispersal.

This is the same image, having been worked over somewhat in Photoshop.
The point is to simplify and thus reveal the important features of the structure of the flower.
What you have left are two of the 6 stamens, each with the two prominent anthers, which are developing to maturity - preparing to shed pollen (dehiscing). There is a structure holding the anthers out to the side to the flower - at right angles (more or less) to the tall, upright pointed stamen. That structure is made more clear in a botanical illustration and a photo below. The pollen grains are held in the anthers. that is normal. But its location at the bottom of the stamen is far from "normal" amongst most "modern" plants. In fact, the botanists regard Sassafras as a primitive plant, (amongst dicotyledonous plants) largely based upon an analysis of the flower structure. That is, it is not regarded as "primitive" compared to ferns, etc. But compared to other flowering plants, it is so regarded.

This location of the anthers (and therefore the pollen) is very different from most plants with which we gardeners are familiar. For example Lilies, or my favourites, Peonies, which hold their pollen high within the flower, to maximize pollen collection by bees.

A pink trumpet Lilium
with pollen very prominently presented on the anthers.Here is one of my favourites, a Tree Peony.
Note the ring of anthers with heavy pollen.

Clearly the Sassafras plants have evolved a very different form of pollination. I recall reading that they are supposedly pollinated by Mosquitoes (perhaps small midges or gnats which I have noticed around in the last few days.) The pollen grains are close to the base of the flower, not at the tip of the stamen, which is the more familiar position.

Here is the "eye" of the flower, cropped close.
(Click to enlarge the image).

Note the ring of 6 stamens forming the outside ring of the central part of the flower. Some are pointing up towards the camera, so they disappear, somewhat. But you can clearly see the 6 bases of the stamens, each with two white bubbles of pollen on the anthers.
There are two dark spots on the base of each stamen.
Inside that ring of stamens are a series of small structures, which are the the "6 alternating shorter staminodes" referred to in the botanical text above. Staminodes are modified stamens, often infertile (having no pollen).
These structures are visible against the green base of the flower.
Right in the centre of the flower are the thin white, pointed carpels (the female parts of the flower).

Here is a botanical drawing of the structure of the stamen and anthers of the Sassafras.
And here is an image of a single stamen and the paired anthers at the base - the result of my "dissection". The green section is the remains of the base of the flower - acting as a handle for my fingers to hold the stamen - allowing its details to be clearly seen.
You can clearly see the pollen ready to be dispersed (a process known as "dehiscence"). If you glance back up the page to the third image, you see a photo of a very fresh flower. Examine the anthers in that flower, at that stage of development. They are hard and white and clearly are not mature - at that stage. The pollen had not yet started to dehisce in that image. Unlike the pollen in this image.

In due course, I shall show some seed capsules and then the actual seeds when they disperse.

King Parrot - R.I.P.

I generally do not photograph "road kills" - as some people might be offended by the images. If you feel that way, kindly go no further. Please come back tomorrow.

*****

In my defence, photographing "road kills" is a great opportunity to show details of birds or animals which one normally does not see, or can only glimpse briefly, at high speed.

This is an Australian King-Parrot (Alisterus scapularis) which had been hit by a vehicle as the bird was flying to or from a wild apple tree, growing beside the Illawarra Highway. The tree was heavily in fruit, and was attracting all sorts of birds, including Rosellas, King Parrots and several Ravens. No doubt the little birds will follow, once the large birds have opened the fruit up to the air, and yeast spores, allowing the fruit to ferment, naturally.

The bird was very freshly killed, and had presumably been hit a glancing blow, because, to put it crudely, it was in very good condition - apart from being dead! (That comment is for Tyto Tony's benefit, as I suspect he is probably a fan of The Goon Show.) After examining it, and checking its freshness, I decided to take some photos to record some details of the bird's plumage.

Here it the top view, showing head, wings, rump and tail. The green head means it is not a mature male. It could be either female or juvenile. Both have green heads.
Here it is seen from underneath. You will notice the brilliant scarlet coloured abdomen. Males have that colour on their chest and head. For a full set of images of all stages of development of Australian King-Parrots, have a look at this site, developed by Alan, of Waratah Software. Here is a close-up of the head. Wonderful glossy green feathers, especially around the eye. The beak is orange-red, but not quite the fully coloured beak of a mature female. Juvenile birds have black beaks. So, I conclude that this bird was probably a female, nearing maturity.
The beak of Parrots is uniquely structured, because the upper mandible is hinged (at the top of the beak) allowing them great flexibility of the beak configuration, giving them remarkable beak agility and control when eating small seeds. Although the tip of the upper mandible (when at rest) protrudes far beyond the shorter, blunt lower beak, because of the hinge in the upper mandible, its angle can be changed, relative to the lower mandible. This allows seed eating parrots to finely crack open even a very small seed between the cutting tip of the lower mandible, and the upper mandible.
To clumsy humans, who can only wiggle our lower jaws around, that flexibility of both beaks seems quite remarkable.

This image shows the rich blue colour on the rump. This is a feature not often observed in the wild. The bird has lost some feathers.The structure of the Tail Feathers.

Here is a rich green tail. The tail is very long - considerably longer and straighter than that of the Crimson Rosella. Now I would like you to study the tail structure in some detail. Tails are very important for birds for control in flight. Expressed very simply, birds use their tails for "steering" and for "braking" (slowing down when landing). Click on the image (above) to enlarge it. There are three feathers clearly visible, with the shining dark central stems (the "shaft" or "rachis") clearly visible. I would like you to examine those three feathers.

• The central tail feather is very well balanced, (left and right) either side of the central shaft.
• The lowest feather, (left hand side of the tail structure) if you look closely, has shorter strands ("barbs") on the outside edge (left) of the shaft, with longer barbs on the inside edge of the tail. That is very evident close to the tip of the feathers.
• By contrast, on the high side of the tail (in this image) - (the right hand side of the tail structure), you can see the reverse of this balancing feature. Here, the shorter "barbs" are on the right of the rachis - which is of course, on the outer edge of the tail. The longer barbs are on the inside edge of the tail. This is the opposite arrangement to the individual feather example discussed above.
• We are looking at a balanced central feather in the tail structure, and two opposite-shaped feathers on the either sides of the tail - which balance each-other out - left and right.

It is all about symmetry (not of the individual feathers, but of the matched sets of feathers) which is essential to the bird's balance, in flight. This is an integral feature of the balance of the bird, in flight - part of the bird's overall streamlining and aerodynamic balance.

Under side of the tail:

This next image shows the highly complex structure of the tail as seen from underneath. You can see that there are matched pairs (left and right) of tail feathers which are not full length feathers. As the tail is closed, these feathers are "filed away" sequentially. They are positioned under eachother progressively, from the longest feathers to the shortest, as you look along the tail (upwards from the tip).

Remember that in this image, we are looking from the underside of the bird. The shortest feathers would be the outermost tail feathers (as the tail is spread, in flight). Then the slightly longer feathers are next. Right down to the nearly full length feathers. Finally, the central (longest) feathers maintain their position as the tail is spread.

So, the shorter feathers would be on the outer edges, and then the entire tail would taper towards those three long central feathers, which we examined from above - in the previous image. When the bird is at rest, the short feathers are neatly folded under the longer feathers, giving the impression of a long, narrow tail.

It is obvious, however, that as the bird needs to spread its tail, for dodging left or right, in flight, or "fanning out" during a landing manoeuvre, the tail could be spread quite widely, for precise control during flight. It is a very complex structure, which the bird can operate, with perfect control, at high speed - something which birds appear to do "automatically". Occasionally, mistakes do occur, as in this case.

But, next time you watch a group of parrots fly up into a tree, remember how much control they exercise to avoid bumping into branches, or to steer around objects. These birds can fly through the dense canopy of a rainforest tree, at full speed - up to 60 Kph. Much of that "steering and braking" control comes from adjustments made to the tail feathers.
The other feature which is evident in that image is the tapered set of red and green feathers, known as the "Under Tail Coverts". The dark spot in the centre, below the feet, is where the "vent" is located. Below that is where the under tail coverts start.

Now for the wing.

The wings are balanced, left wing and right wing, but the individual feathers are strongly asymmetrical. Considered overall, the two wings are balanced, with oppositely shaped feathers. Otherwise birds simply could not control their flight.

Wikipedia has an interesting article on flight feathers of birds here.

The longer feathers, "the Primaries", the main feathers used to gain thrust in flight, are especially asymmetrical. The tapered feathers allows for gaps at the wingtip; air is forced through these gaps, increasing the generation of lift (according to Wikipedia).

You can tell how the feathers sit when the wing is closed, by noting the fine green stripe of colour on the leading edges of these feathers. The green bit is the only part of these flight feathers which is visible when the wing is closed. So the amount of "overlap" when the wing is closed increases progressively as you look further out on the wing. Judging by the very fine green edge of colour, the very furthest out feather only just protrudes beyond its nearest neighbouring feather when the bird's wing is folded closed. But in flight, it can be spread wide, to maximise the thrust and lift achieved by the bird's wing strokes.

As you come back along the wing, (closer to the body) the "flight feathers" get progressively smaller - the "secondaries" and the 'tertiales". Above the flight feathers are layers of ever smaller feathers, which are referred to as the "upper wing coverts".
It is worth noting that there is a sexual dimorphic feature on the wings of male King Parrots. The males (only) have a light green stripe on the wing coverts. This feature is strongly visible in the ultra-violet spectrum, which parrots and some other birds can see.

The Birds on Backyards site says: "Although King-Parrots appear distinctly red and green to humans, when viewed under ultraviolet light, some feathers on the wings appear with a prominent yellow glow. Many birds have four types of cone in their retina, (compared to only three in humans) and see into the ultraviolet wavelengths." It is assumed that this highly visible patch of feathers gives the birds some competitive advantage when courting a potential partner.

This next image is simply the same wing image, cropped and reversed, to see the wing as one would see it looking outwards from the body of the bird. If you click to enlarge the image, you will see it at maximum pixellation. You can clearly see the tapered "barbs" on the individual feathers, and the increasing asymmetry of the flight feathers, and one looks further out to the leading edge of the wing. There is one feather (3rd down from the top, in this image) where the barbs, which are normally held together by a series of minute hooks between the individual barbs, have separated, breaking the smooth line of the feather. This shows how important those minute hooks are, in keeping the aerodynamic structure of the feather. Broken feathers or feathers with the barbs separated like that, would greatly reduce the efficiency of the wing strokes. That is why birds spend a lot of their time "preening" themselves, re-aligning the barbs on their feathers, and allowing the minute hooks to join back the barbs of the feathers. Damaged feathers are replaced by moulting, when old feathers drop out, and new ones grow to replace them.

Finally, here is a view of the legs and feet. Parrots have two forward pointing toes (which are relatively long), and two thicker, stronger, backward pointing toes ("zygodactyly"). When the foot is closed, the forward pointing toes nestle in between the two rear toes. The claws on the rear toes are very powerful. These are the main toes used in perching. Normally parrots reach out with their beaks to chew plant seeds directly from the plant. However, the feet are also used sometimes by parrots and cockatoos, in gripping large items of food, to hold it up to the beak, when eating. Parrots are much better adapted to this method of feeding than just about any other group of birds. Owls have a similar (but not identical) toe structure, but they use their feet from grasping food, and for carrying it to a perch. But they do not hold their food up to the beak, as parrots do.As anyone has ever observed parrots feeding on the ground will be aware, they have very short but powerful legs. Here you can see one of the legs, the lower joint, at least. You can also see how strongly scaled the legs and toes are. These scales are much thicker than in Passerines (perching birds), which tend to have long flat scales sheathing the leg bone, more or less like a thin plastic coating.

The Nature of Fire - Part 2 - survival strategies of plants

I promised yesterday that I would talk about how different types of plants survive fires. In truth, it should be how different types of plants "deal with" fires.

This is regarded as an evolutionary issue, in that many of the plants with good fire survival strategies are "modern" plants which are understood to have evolved as Australia drifted further north, and progressively dried out, to become the fire-ravaged "sunburnt country" which it is today.

*****

I mentioned yesterday that the Eucalypts survived these cold burns, with little or no damage. That is due to their thick bark. But we all are familiar with the fact that even after a devastating fire, most Eucalypts can re-shoot from dormant buds hidden under their bark. So, even though the leaves get totally burnt, the stem is scorched, but not killed (usually). Within weeks of a fire, new shoots appear all over the plant. After a few years, the plant settles down to normal growth.

Acacias have very hard seeds which fall as their seed capsules ripen, every year. But the seeds can remain viable on the forest floor for years. After a fire, these seeds will germinate, as the hard coating on the seed will have been cracked by the heat of the fire, allowing the seed inside the coating to absorb water, and start to grow.

Some plants have thick bark on their trunks, which protect the living tissue of the plant from the heat of the fire, and, although the leaves may be burnt, they can regenerate quickly, after a fire. Surprisingly, the Rough Tree Fern, Cyathea australis, is such a plant. It is rainforest plant, primarily, yet it has a good fire survival strategy. That is an unusual combination, as many rainforest plants are notoriously weak at surviving fire.

Indeed that point is the flip side of my opening comments on modern plants having evolved to suit Australia's increasingly dry climate. That adaptation involved surviving fire. Many of the local rainforest plants are of ancient lineage, having evolved when Australia had a wetter, colder climate than it does today. That is why they are plants which tend to grow in remnant pockets of rainforest, in wet patches (such as Robertson), which is not very susceptible to bush fires.

*****

Within the Eucalypt forests of which I was talking yesterday, the most obvious fire survival strategies are: flaky bark, to protect the trunk; suckering from a root stock protected under the soil and storage of seeds, which open after the fire has passed.

Persoonia linearis - flaky bark.


Several of the local Persoonias (Geebungs), Persoonia linearis and P. levis, both have thick flaky bark, which gets singed in a fire, but which protects the living layer of tissue in the trunk (the cambium).








Persoonia linearis - singed by fire.


This shrub has been singed by fire, but it will probably re-shoot successfully, because of its protective bark. The leaves will have been killed, but new growth will occur.










Persoonia linearis produces lots of fleshy fruit.
These plants also produce an excess of fruit, which are often seen lying all over the ground, under the shrub.

Persoonia seeds are notoriously hard to germinate in cultivation, but seedlings are commonly found in the bush. One explanation is that birds and animals eat the seeds, and in so doing "treat" the seeds in their digestive systems, in a way that favours germination.

However, there are also reports that some species of Persoonia are found to have good germination after fire. So, presumably some of these seeds, (which appear to have a very long germination period), might remain viable in the soil, and then germinate, in post-fire conditions.

Waratahs, Lomatias and at least one of the local Persoonias (P. laurina) all are obviously suckerers. A quick walk through this forest will show you that. Look at your local Waratah - if there is one plant growing, there will often be a series of smaller plants close by. Often you will find a taller dead plant (burnt) with regenerating plants around it, in a circle. The Lomatias and the little Persoonia are less obvious plants, but their strategy is the same.

Then there are the Banksias and Hakeas. These plants have a sacrifical strategy when it comes to fire. The adult plants have little or no resistance to fire, and simply die when a fire occurs.

But they have woody capsules in which their seeds remain viable for many, many years. Then, when the fire is raging, the seeds are protected inside these hard woody capsules. But within days of the fire passing, the old woody capsules slowly open (like oysters), and the seeds fall out, onto the ash layer on top of the soil. That ash contains chemicals from the burnt wood which has been found to promote germination of these seeds. Indeed, many native plant nurseries use "smoke treatment" for the same reason, to greatly promote the germination of native plant seedlings.


Old Native Plant books used recommend growers heat treat seed capsules of Hakeas and Banksias, in order to get the capsules to open and release their seeds. The usual method recommended was to put them in the oven, after someone had been cooking, and the oven was cooling down. That technique misses out on the "smoke" effect, but one can buy "smoke water" to soak seeds in, from many native plant specialists.

Pairs of curved seeds may be seen emerging from some of these woody capsules on the burnt seed cone of Banksia cunninghamiana.


These Banksia cones might be regarded as "time capsules", holding the seeds in virtual suspended animation, waiting for a fire to come and open the capsules with its heat, before the seeds can be safely released. In a few months time, there will be lots of young seedling growing near where the old plant died. That is why I refer to it as a "sacrificial strategy" - even though fire kills the main plant, the species will go on.

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I mentioned yesterday, how dangerous it is if fires occur too often.

Some species, such as the Banksias, and Acacias, rely on seed in order to survive a fire, as the plant itself is killed by fire. So, in order for the species to survive, it needs to have set seed.

Many plants take a number of years to reach maturity. They need to have reached flowering age, been pollinated, and then to have set seed, before they are able to survive a second fire. So, if, for example, this area was burnt off now, and then, in 3, 4 or 5 years, it was re-burnt, it is entirely possible that Banksias would be eliminated from that patch of forest. For some plants, this maturity cycle might be as long as 8 years.

So, repeated burning, as a forest management strategy can result in producing a "forest" with a live canopy of Eucalypts, but little of no understorey of shrubbery. That is not a real forest - it is a "treed desert" - with few species of plants, and even fewer birds and animals.

Unless the people who set fires like these ones, understand that, they risk permanently damaging the living forest, if they burn it too often.

Indeed, even if they do understand it, who is to say that any subsequent fire might not be a major bush fire which might occur naturally, in circumstances totally beyond the control of humans? If such a devastating fire occurs within that 8 year time period, the damage can be permanent.

Even if the subsequent fire is not lit by people, but is entirely natural, the result is the same.

The Nature of more odd Australian plants

Hakea laurina - flower just opening
Following up on the earlier Blog about Grevillea flowers, I thought I would show you a photo of the supremely weird, wonderful and lovely Hakea laurina. For Leo's benefit, the entire "flower" is roughly the size of your beloved golf balls.

This plant starts out with a rounded bud, tightly encased in sheaths of a silky-covered papery substance. The sheaths fall off, as the "flower" opens. That reveals a tightly packed composite head of many hundreds of flowers.

Each flower has the same basic structure as the Grevilleas discussed yesterday. the main point of comparison is the dominant styles (white with green tips) which start out bent like a hairpin, but which, as they mature, open outward to form this "sea urchin like" flower.

In the photo above, the individual flowers on the right have matured, and the styles have all opened out. The ones in the centre are just opening, and the ones on the left are still developing.

Detail of Hakea laurina flowers

This shot (not as sharp as I would like, sorry), does at least show the intimate details of the flower structure. In the centre, you can see some flowers where the stigma has just opened out, leaving the four segments of the original outer casing of the flower still "exposed". Those dark pink patches are where the pollen is formed, before the style opens out, taking the pollen with it. It is not clear in this photo whether these particular flowers have any pollen on them, but that is how the mechanism is meant to work.

You can clearly see many flowers with the style still "in position" inside the flower "tube", before they open out. Some are just opening.

Grevilleas have a seed casing which is leathery, and which opens along one side, to release two seeds. They drop their seeds every year, generally. By contrast, Hakeas have a hard woody seed casing, which splits to release two papery winged seeds. But the seed casings might stay on the bush for many years, in anticipation of a fire, after which the seeds are released, to germinate on the freshly potash-enriched ash soil. Fire survival and fertiliser strategy, all in one.