Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis
Showing posts with label Proteaceae. Show all posts
Showing posts with label Proteaceae. Show all posts

Saturday, October 10, 2009

Helicia glabriflora - in Robertson (typo corrected)

Helicia glabriflora is yet another plant which has its southern-most range in the Illawarra. In fact, this tree is reported to be the most southerly member of the species - growing here by itself here in Robertson. A loner.

I photographed this tree when in flower, in February last year, which is more or less its normal time, it seems. But when I was checking Tangle-root Orchids the other day, I noticed that this tree was in flower - which surprised me, as I remember it as flowering in high summer, normally.

It also has some fruit on it, which are not yet ripe, as they turn bright blue when ripe. But the fact that it successfully set fruit last year is encouraging.

This plant is in the Proteaceae tribe, but it does not look at all like its normal southern relatives. It is a rainforest tree and in Robertson is hard to distinguish from the neighbouring Sassafras trees, which have similarly bright green, shiny leaves. Its flowers (inflorescences) look nothing like the Waratahs or Grevilleas which we tend to think of as "typical Proteaceae" plants. But in truth, there is no such thing.
Here are the unopened buds on a flowering stem (inflorescence).

In fact the flowers and fruit of the Helicia most closely resemble (in structure) the Persoonia family. Many members of the Proteaceae tribe are tropical plants, which look very different from our most familiar members of the tribe. If you remember that the nut-bearing plant, the Macadamia, is a tropical Proteaceae plant, that will give you some idea of the diversity of this tribe of plants.
Opened flowers on the full inflorescence (stem)
Compare this with the photo of the Macadamia
Here are two (paired) flowers arising beside eachother on the flower stem.
This is typical of many members of the Grevilleoideae.
I have shown this same feature in Grevillea flowers

This pair of flowers has pollen dusted onto their Stigmas.
These plants use the Stigma, (the female part of the flower) to act as
the "pollen presenter" as in this case. The pollen is ready to be picked up by a bird or an insect, to be taken to another flower.
Here is a single flower (removed from its paired flower - to simplify the image). The outer skin of the perianth (seen fully closed in the bud image at top) splits, as the flower matures, and the perianth segments (tepals) roll back, down along the stem. This is referred to as being "revolute".
"Perianth tubular; tepals revolute at anthesis." (PlantNET)
After maturing, the tepals drop off the flower, leaving only the style (which had the stigma at its tip, and leads down to the Ovary at the base). In this case, you can see the ovaries of these flowers are starting to develop. They are the orange-cloured swellings at the base of each style.Here is an unripened fruit (still green, not blue). But you can see the "persistent style" protruding below the fruit (on the right). The fruit is, of course, developing where the "ovary" (the orange swelling - above) is located in the original flower.This fruit, with the style protruding, looks very similar to a Persoonia fruit.

Saturday, June 27, 2009

Protea flower parts - in detail.

Several weeks ago, I showed some lovely flowers of a popular hybrid Protea "Pink Ice". Here is the primary parent plant of that hybrid.

According to the Planzafrica.com website, Protea neriifolia was the first protea ever to be mentioned in botanical literature. It is a South African plant (of course). It was first discovered in 1597, and was apparently was first illustrated in 1605. It was described and named in 1810. The name refers to the similarity of the leaves to that of the European plant - the Oleander (Nerium sp)Today it is my intention to examine the details of these spectacular flowers. Of course, in Australia, we have many plants (Waratahs and Banksias and Grevilleas to name the most familiar) which the botanists recognised easily as related to the Proteas - hence they are referred to as members of the Proteaceae family. However, to the untrained eye, the differences are more apparent than the similarities. I wish to concentrate tonight on the similarity of flower structure (with some of our flowers).

When I started this investigation, the first thing I felt was "odd" was the tuft of little "feathered tips" in the centre of the Protea flower. Then I decided to pull out several of these flowers to examine them in detail. Two things happened. The flowers broke off half-way down, with a long thin tube still protruding down to the base of the "flower" (the entire head, I mean). Clearly that would have been the tube through which the pollen grains grow down to the ovary at the base of the flower. The second thing was that my fingers were suddenly covered with pollen, which surprised me, for I had been looking to see where the pollen grains originated, but had not seen them. At least I knew they were there somewhere. Time to look more closely.
Firstly you need to understand that what we see as a flower in in fact a composite flower structure - which is composed of many flowers grouped together inside a set of surrounding bracts. It is the bracts which we see as the main part of the flower - but in botanical terms, the bracts are mere "window dressing". They simply serve to protect the true flowers as they develop.

A Protea flower - an individual "true" flower I mean - does not have separate sepals and petals. Instead, there is one set of four perianth segments (called tepals). Initially these parts are fused. As the flower matures, it ruptures open.

Following up from my first experiment to pluck out a flower (which did not work), I realised I had to break open an entire flower head (removing some of the external bracts), to approach the many flowers from the side. That worked, and in the next image, you can see the "feathered tips" of the tepals, close up.

You can also see the lipstick pink tips of what are similar to our Australian proteaceae flowers - the "pollen presenters". Technically, this is the tip of the style. It is the female organ of the flower, but it acts as the male part of the flower temporarily. That will be familiar to readers of this blog - for it is the secret to their pollination.
This is one of the things which the Proteas have in common with our own Proteaceae flowers, although our plants tend to have a curved flower, and a style "pops out" to the side, under pressure.
This Protea style does not to have that curved shape - just a slight bend near the tip, visible here, just below the red coloured section.
The four tepals are fused into a long narrow tube with a closed cup at the top. (That is the bit which has that feathered external appearance). Inside the perianth, the four stamens are fused to the tepals, in such a way that the anthers are enclosed within the cup. The pistil initially passes along the inside of the perianth tube, so that the stigma too is enclosed within the cup. As the flower develops, the pistil grows rapidly. Since the stigma is trapped, the style must bend in order to elongate, and eventually it bends so far that it splits the perianth along one seam. The style continues to grow until anthesis, when the nectaries begin to produce nectar. Just before anthesis, the anthers release their pollen, depositing it onto the stigma. At this time, the perianth splits apart, and the pistil is released to spring more or less upright. Then the tip of the pistil (the "stigma") functions (for several days usually) as the "pollen presenter". Hopefully a suitable pollinator will visit the flower to get the nectar, and will be dusted with pollen. Once the pollen dries, it falls off the tip of the stigma, which then assumes its true female (receptive) function.
You can see the pollen on the Stigma in this image.
(Click to enlarge)
The male organs (anthers) of Proteas are also distinctive. The anthers do not have long stalks (filaments), but are joined directly to near the top of the tepals. Unlike most other plants, the anthers shed their pollen onto the topmost portion of the style just before the flowers open. Because the style presents the pollen in a position suitable for placing onto any visitor, the top-most portion of the style is called the pollen-presenter. The presence of a pollen-presenter is another diagnostic feature for Proteas. It allows the pollen to be "dusted" onto the natural pollinating vector, be it an insect, a bird or a South African mouse (or Honey Possum for Australian members of the Proteaceae).
Note the split in the perianth. That is where the pollen came from. In this regard it is functionally similar to the Waratah and Grevillea flowers. Click to enlarge the image above to see what I mean.

Four nectaries are apparently situated at the base of the ovary, between the ovary and the tepal bases. These secrete nectar to attract pollinators. Source: Protea Atlas Project

One thing which I have not managed to understand yet is why our Proteaceae flowers split into 4 separate perianth segments, but this Protea seems to keep its anthers closed within a single tube - even after the style has split out. From this reference document, it is obvious that many South African Proteaceae do behave in ways more similar to our Waratahs and Grevilleas (than this Protea does).
.

Monday, June 01, 2009

Protea "Pink Ice" flowering in my garden

When I moved to Robertson I was aware that the rich red basalt soils here are good for growing Protea plants and their relatives, such as the native Waratahs. The reason I knew this is that the plants I was intending to grow here, Peonies, grow really well in Monbulk, in the Dandenong Ranges (Victoria). Monbulk is famous for its rich red basalt soil - just as is Robertson (in NSW). Monbulk is home to Australia's largest specialist Protea propagation nursery "Proteaflora".

So, naturally, as I was establishing my garden here, I planted some of the members of the Protea tribe - Leucadendrons, Proteas, Banksias and Waratahs, and Grevilleas. This was largely an experiment, to see how they would grow, for some, especially the Grevilleas, are said to be very fussy about soil, preferring poor, low-nutrient soils. But most have done very well indeed. Some have exceeded all expectations, notably the Banksia "Giant Candles" which has had to be beheaded several times already to prevent it outgrowing its roots, and suffering wind damage.

The reason for the "caveat" about the soil is that very few members of the Proteaceae tribe grow here naturally - but members of this tribe of plants are very common just a few kilometres from here on the sandstone plateau below the Robertson range. It seems the reason is that the local rainforest plants survived so well, prior to European settlement and clearing of the land that the native Proteaceae never got a chance to "invade" the basalt. There are only two exceptions to this principle that I know of - a Helicia (of which there is but a single specimen left, apparently), and the tall rainforest tree Stenocarpus salignus.

One of these plants which has done particularly nicely, and grows only at a moderate rate, has turned out to be the popular hybrid Protea "Pink Ice". I bought my specimen Protea "Pink Ice" from Wariapendi Nursery at Colo Vale, NSW (near Mittagong), one of many nursery outlets for"Proteaflora" plants in NSW.

Here are the results:
A bud just starting to develop.
The black marks on the outer sheathing bracts are distinctive
from a related plant, Protea neriifolia, whjich is one of the parent plants to "Pink Ice".Here is the next stage of development of the bud.
It is very elongated overall, and narrow in the tip.
There are many black fibres in the tip of the bud, at this stage.
As the flower opens, the top broadens out.
Suddenly the profile of the flower changes, just as it opens.
It is almost "square cut" at the top, with masses of silvery fibres.
Here is a top view of the flower.
You can see what I mean about the silvery fibres.
This flower has not yet opened fully, but I would have to say that
this is my personal favourite stage of development of the flower.
There is one further stage of development, which is yet to occur. So I will show the fully opened flower shortly (when it opens). The flower becomes chalice-shaped.

Tuesday, October 21, 2008

Waratah flowers - details

The Waratah flower is actually a complicated structure of paired flowers, joined into a head, which is classed as a "terminal conflorescence" (according to the Botanists). This means, as we can all see, that there is a large flower structure (composed of many individual flowers), at the end of a branch. There is a circle of bracts (modified leaves) which served to protect the flowers as they developed (follow this link to see a photo of the bracts curled up around the flower). The bracts also make the entire flower head more prominent, visually.

What these photos do not show is the bit about the flowers being held "in pairs". That is a botanical distinction which indicates (to botanists) that these flowers are related to members of the Grevillea genus. I shall show some Grevillea flowers in a few days, where that point will be more evident.

Today I wish to concentrate on the intricate flower structure which Waratahs have developed, and discuss the implications for the pollination process of Waratahs.

Where to start? Well, we know that Waratahs are attractive to birds and to bees. That is because they produce copious amounts of nectar. Their red colour also helps make them attractive to birds (for birds "see" red colours very clearly - because of their special optic nerves). In Australia, a whole tribe of birds has evolved along with these Australian members of the Proteaceae group of plants. These plants which are similarly shaped, (nearly all tubular flowers, with nectar). And so there is a mutual dependance arrangement going on, between the Honeyeater tribe of birds (from tiny Spinebills to large Wattlebirds) and this group of related plants. Gardeners and Birdwatchers know this, for they are always talking about planting out "bird-attracting" gardens.


How does it work? This shot shows three flowers from closed bud stage (lowest) to open, and then fully open (top). What it does not show is the "nectary" which is a tiny gland deep within the base of the flower. However, when you look closely at a waratah flower, when it is freshly opened (usually just the first few rows of flowers at the base) you will see tiny gleaming droplets of nectar, inside the curled parts of the opened flower. In some cases, the nectar will leak out, and collect on the red bracts at the base of the flower. In which case, expect ants to be attracted to these flowers.

As the individual flower matures, the style (the long pointed part of the flower) straightens out, and emerges backwards from a longitudinal split in the tubular part flower (which is known as the "perianth"). Then the perianth lobes curl arond on themselves, and shrink back down towards the base of the flower.

From the point of view of pollination, the trick is that the anthers in these flowers are held deep withing the tube (the perianth) and do not protrude at all. That means that unlike many familiar garden plants which present masses of pollen (on long anthers), which makes their pollen readily available to insects, the Waratah and other related plants, use what is known as a "pollen presenter". This is the most remarkable part of their trick, for the "pollen presenter" is in fact the female organ of the flower - the "stigma". But for the first few days after the flower opens, the stigma is not mature (as a female organ) and instead acts to carry the pollen which has been stuck onto it when it was curled up inside the (previously unopened) flower. In the image above, you can see there are four dark dots inside the curled perianth segment. Those are the male anthers, and while the flower was still unopened, and the style was still curled up inside the tube, the stigma (the pad on the inside edge of the style) was in a position to touch the anthers. So, the stigma collects the pollen from the anthers, and as it opens out, it takes the pollen with it.


In the next image, you can clearly see the dark brown coloured pollen on the stigma - the inside of the point of the style (curved rod).



The next stage is less visible. The pollen dries up, and then the face of the stigma (the "inside face" of the curled style then become mature as its female stage, and becomes sticky, ready to receive any pollen from another Waratah flower which might be brushed onto it by a passing Honeyeater, or bee.


The curved shape of these flowers is important, for Honeyeaters have long thin, curved beaks which they use to poke inside the tubular flowers of the Waratah, in search of the reward of some nectar. As they do so, they touch the pollen presenter, and receive a dusting of pollen on top of their forehead (or just around the beak). The bird then goes off to another flower. And if that flower is at the slightly later stage of development, when its female stigma is now mature (sticky), it till be able to receive pollen dusted onto it by the bird's feathers on its forehead.

You will often notice a Honeyeater (of some description) sitting on top of a Waratah flower. As it reaches down toward the base of the flower, to get the nectar, its head will come down from above the flower, making a perfect match between its forehead and the position of the stigma. That is why Waratah flowers are shaped they way they are - to suit the pollinators which have evolved with them.

I noticed today that my blogging colleague who writes "A Snail's Eye View" has written a report on pollination structures in Western Australian Banksias, which are related plants, despite some apparent differences. Their internal flower structure is very similar, and hence the pollination process is nearly identical, except that they rely more on insects, and tiny "Honey Possums" for pollination. Banksias develop a woody cone after pollination, whereas Waratahs develop a pod. Apart from that the pollination system is very similar indeed. You can also clearly see on Snail's Blog that Banksia flowers are also held in "pairs", even though the overall structure is also a "conflorescence" (as is the Waratah head).

In an example of "parallel evolution" many red tubular flowers in Central and South America are pollinated by Hummingbirds, which are not particularly closely relate to our Honeyeaters, but which have adapted to feed on long tubular red flowers. As they do so, Hummingbirds receive dobs of pollen on their foreheads, from the plants, which they then take on to other plants. Sound familiar?

In my opinion, this is just an illustration of the fact that plants have shaped the world to suit their interests.

And we like to kid ourselves that we are the "masters of the universe"?

Wednesday, August 29, 2007

Budderoo plateau bushwalk today

I led a bush walk for the National Parks Association (Southern Highlands branch) today. It was out on the Budderoo Plateau, which is close to (and similar to) the Barren Grounds. For more details follow this link. I suggest reading the sections on "Landscape" (bottom of P. 7 onwards) and then, "Biological values" on pages 8 and 9.

We stopped firstly at a very nice patch of heathland, which Jim and I had found last week, when doing a reconnaissance visit. We found many plants flowering which were members of the "heath" family (Epacris plants and their relatives). There were many species of the Proteaceae group (Persoonia sps, Banksia sps, Petrophile and Isopogon), as well as some specimens of Symphionema paludosa, which is such a small plant it it seldom seen. In addition, there were many tiny "Sundew" plants (Drocera sp.) one of which we spent some time examining in close detail, with the use of 10x hand lenses. There were tiny insects caught on their leaves - gnats or midges, I would imagine.We also found some tiny lichens which were carrying their little red capped fruiting bodies. Most people in the group had never ever seen these tiny lichens with such "fruiting bodies" before. I love these tiny little lichens - barely 3 cm high, with little scaly stalks, each topped with one of these little red "boxing glove" type structures which is the "fruiting body" for the lichen.

We then adjourned to Wallaya, a property owned by Penny and Larry, where, after a brief refreshment break, we walked down a long grassed slope to a patch of tall wet Eucalypt forest. The forest edge is only about 100 metres deep on the northern side of the block - at which point it opens out to reveal a sandstone cliffline, with dramatic views of the Gerringong Creek valley below. Last week, there was a smal (un-named) waterfall flowing off the far side of the valley. It was barely flowing today (as the country had dried out considerably over the last week).
One of the many plants which favour this sandstone cliffline is this species of Phebalium. The flowers are pale cream, and the leaves are very narrow (and pungent). It is likely to be a form of the highly variable plant Phebalium squamulosum.
There were other "rock-loving plants" there, including Epacris calvertiana var versicolor and many wonderful specimens of Dracophyllum secundum (a large-leafed member of the Epacris group) which has distinctive leaves, almost resembling tiny pineapple leaves, in their early stages of development. Then the stems lengthen out, producing flower sprays, with typical pale pink tubular flowers. This plants roots often are found growing great distances in moss on wet faces of rocks. Dockrillia striolata (Streaked Rock Orchid) were found in abundance, growing in crevices in rock faces. Where the plants were growing in more exposed places, their leaves were distinctively reddish-bronze, otherwise they were green. These plants have an almost succulent-like appearance, having a thick outer coating on their narrow leaves which are almost triangular in cross-section. Last week, I also found a patch of the tiny Rock Orchid Bulbophyllum exiguum, but I did not find them today. I was probably looking on the wrong rock - they are highly particular in their choice of habitat.

It always fascinates me that a rocky clifftop, such as this can have such a totally different plant habitat and species list from that of the forest a mere 20 metres away. And even the forest is graduated, with tall Banksia serrata plants as the first line of tall trees, then they give way to Turpentine trees (Syncarpia) , then to a mixed wet-sclerophyll forest of tall Eucalypts, with patches of rainforest plants growing as understory shrubs. All this variety within a mere one hundred metres distance from the cliff edge.

I really enjoyed being with this group of people who appeared to have appreciated the very varied range of plants and habitats, with nice views - and good company thrown in.

Saturday, June 17, 2006

The Nature of the Woody Pear

The Woody Pear is a weird plant.

It is a member of the Proteaceae family of plants - along with the better known Waratahs, Banksias, Hakeas and Grevilleas.

But it has a very different "fruit" from those plants.


Both the common and scientific names refer to its distinctive pear-shaped fruits (see left). Its specific name is Xylomelum pyriforme. The scientific name breaks down to woody fruit - with a pear shape.

But unlike a pear, they are attached at the "fat" end.

The "fruit", although pear shaped (but upside down) is a hard woody capsule.





That capsule opens along one side, to release two winged seeds. In that regard it shows its relationship to the Hakea family.





However, its fruit are much larger than those of the Hakeas.



The leaves of Woody Pears (as juvenile plants - ONLY ) are sharply toothed along their margins.


As a small plant on the forest floor, they could easily be mistaken for a juvenile Waratah, or else a member of the Lomatia genus (both of which groups are related plants, and which grow in the same areas as these plants are found).


As the plants mature, their leaves change quite dramatically.


When the plant is mature, its young leaves (new season's growth) are noticeably pinkish. However, these pinkish leaves develop a green pigment, as they mature.



They change into this bright olive-green colour. Both these stages of leaves (the pink and the green stages) on the mature plant have lance-shaped leaves, with smooth edges. The botanists refer to them as having "entire" margins.

The pictures are useful to show both leaf shapes.

The texture of the leaf is distinctive, though, once one looks closely at it (have a close look at the photo above). It is heavily veined, with a strong, dominant mid vein. There is a bold net-like veining which is quite obvious, especially when viewed through from below, in good light, as in the photo above.

These plants are far from obvious, growing amongst the heavily timbered Eucalypt forest, below Robertson, on the deeper soil areas, over the sandstone base. I would consider them to be "uncommon" in the Robertson and Kangaloon area. (They do not occur naturally on the red basalt soils of Robertson itself). Nor do they appear to favour the poorer, shallow, sandstone soils, for example along Tourist Road.

There are good stands of these plants which may be seen on Mt Gibbergunyah, and some on Mt Alexandra. Both those mountains are in the Mittagong/Welby area.

These plants grow as a mid-storey plant (a tall shrub). In this case these Woody Pears are growing in a group, below tall Eucalypts. But in their manner of growth they resemble sapling Eucalypts.


With their long, strap-like leaves, they are easily overlooked as if they were just young Gum Trees.



According to the reference books, these plants are a "protected species". No part of these plants may be picked. Unfortunately, I have seen the "Woody Pear" fruits on sale in florist shops, for use in floral art arrangements. That practice is apparently illegal. Let us just admire them, in the bush.




Wednesday, May 31, 2006

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.

The Nature of Grevillea Flowers

There are many "typical" forms of Grevillea flowers, and here I have just a few of them. These were taken at the Australian National Botanic Gardens, in Canberra, last week. I only had time for a quick trip around the place on an Electric Scooter, on a day out from hospital, so I just got a few photos. Sorry.



Even worse, I did not get to record the species names. Sorry, but I was being rushed.



Mostly these were flowers on shrubby Grevilleas, some quite small plants, others large shrubs. None of these were trees.





This is a "Toothbrush" form of Grevillea flower, just opening.

These flowers are individual flowers, grouped together in a composite structure (an "inflorescence"). If you look at the prominently visible, individual curved protuberances, each one is the "style" (the female part) of a single flower. It has burst open, after being curled up inside the original curled part of the flower.

At a rough guess, there are probably 50 individual flowers in this head of flowers.

This is a tightly formed "Cats Paw" form of Grevillea flower, from Grevillea alpina, I believe. All of these flowers are still unopened, and very tightly curled up.

It is at this point of time that the long styles (seen above) are tightly in contact with the male part of the flower (where the pollen is formed). When the flowers open, and the styles protrude, they come out dusted with pollen, which is then available to be collected by bees, or rubbed onto the heads of Honeyeaters, which come in search of the nectar which is found deep inside the flowers. At that freshly protruded stage (better seen in the Toothbrush" illustration above) the "style", while still dusted with pollen, is described as a "pollen presenter" - it is a female part of the flower, but it acts initially to present the pollen in a convenient location, to allow the pollen to be spread from flower to flower.

If you look closely (double click on the photo of the "Toothbrush" flower two photos up), look closely at the "styles" about 7 or 8 in from the right. They are very obviously "dusted in pollen". After several days, when the pollen is dispersed, or has dried up, the "style" then becomes mature, goes noticeably sticky on its end, and then acts in its true nature, as the female part of the flower, ready to collect the pollen from any passing bird or bee. This system of pollination is the same for the major members of the Proteaceae family, in Australia, the Waratahs, Hakeas, Banksias and Grevilleas. They are all closely related plants.



At left is a less common flower (inflorescence) form (amongst Grevilleas), where the flowers are displayed along the stem. The flowers are all in pairs, which is typical of all Grevilleas.

So, no matter what the form of the flower cluster, be it "Toothbrush", or "Cats Paw" or whatever, if you look closely into the composite flower structure, you will find pairs of flowers in all Grevilleas.



Possibly the largest of the Grevillea flowers, on the Grevillea robusta, (the tree is known as the "Silky Oak") is a "toothbrush" form of flower, but it flowers in summer, so I could not photograph it now. It is typical of a group of northern Australian Grevilleas, many of which are trees, not shrubs, and which tend to have yellow flowers.



The role of colour in pollination:


There is a theory that flowers which are bird pollinated are advantaged if they are brightly coloured, especially red coloured. (Butterflies appear to like yellow flowers, such as Everlasting Daisies.)



One group of Grevilleas which I missed out on getting a photograph of is the tiny little creamy- white flowered flowered forms. They are apparently insect pollinated. They generally have a sweet honey scent, but with such tiny flowers that birds cannot possibly pollinate them. The general theory is that they are pollinated by moths, which fits with them mostly being coloured white or cream (to aid the night vision of moths).


Certainly being coloured red or yellow is an advantage to those which are bird pollinated. However, there are some which are dull green and nearly invisible to the human eye, and yet the birds find them perfectly well. So, some theories break down, if you investigate them closely enough.

Monday, March 27, 2006

Autumn evenings, and migratory Honeyeaters.

The wonderful cool freshness of Robertson evenings is seldom as comforting as in early Autumn.



Another comfort is Anni's blog, where she continues to intrigue us with the breadth of her imagination, and occasional clever photographs, such as today's self-portrait in a teaspoon (the photo is relevant to her story)


We have had a string of balmy days, with clear air, and temperatures in the high 20s, but dropping to the low teens, over night. Weather watchers could do worse than visit the "Mittagong Weather and Weather Cam" website. It is a weather statisticians dream.


My personal gauge of the changing of the seasons is the first sign of migratory Honeyeaters passing through. Yesterday I saw my first migrating Yellow-faced Honeyeaters (Lichenostomus chrysops) for the season. Today I saw a few more. There is no spectacular wave of migration with these birds, unlike images from Europe and North America of migrating Geese and other wildfowl.


These little birds drift to warmer climates, and to coastal feeding grounds, from their summer nesting grounds in the high country in southern NSW and Victoria. But they form small flocks, currently a mere handful of birds. They fly in small groups from one tall tree to another, in short distances of perhaps 200 metres at a time, then rest for a few minutes, then fly on. In a few weeks time, the numbers of birds in these groups will swell to 50 or maybe 100, and the frequency of the passage of these groups will also increase. Just because it is not a spectacular flight of passing birds, does not mean it is not a real migration.


I can tell these birds are migrating, quite simply, because they do not reside in the Yarrawa Brush over the summer. These Honeyeaters are birds of the tall Eucalypt forest, primarily. But they migrate to coastal heathlands, to arrive when the nectar-rich Banksias are coming into flower. So, over the summer I see none of these birds here in Robertson. But they pass through in autumn, and again pass through on their way back, in spring.


Incidentally, these birds do reside a mere 5 Kms away, on the sandstone based forests, down along the Belmore Falls Road. I am not saying that these migrating birds come from there, simply, just pointing out how specific their choice of habitat is. Belmore Falls, has sandstone-based scrubland and Eucalypt forests, with many proteaceous shrubs in the understory. That environment suits them as a breeding ground. The Yarrawa Brush, cool temperate rainforest country does not. The difference is primarily that our trees do not produce the kind of nectar supplies that these birds need. So they do not breed here. They fly through to get to other environments which suit them, for the autumn and winter seasons. Typically, that is the coastal heathlands of the NSW coast where many Banksias flower at the suitable time for them - autumn and winter. (Photo above is courtesy of the Macleay Valley Coast birdlist, on their Tourism website.)


Food sources is the limiting factor in this migration, by the way, not temperature. This is demonstrated by the fact that every year a small number of these Honeyeaters overwinter in the Australian National Botanic Gardens, in Canberra. Canberra has far colder winters than the Southern Highlands. But the Botanic Gardens has a cultivated collection of suitable food plants for these birds, with thousands of Grevilleas and Banksias, which flower over the autumn and winter seasons. So, a number of birds stay there, instead of migrating through to the coastal heathlands.

Wednesday, February 22, 2006

Gondwana

Gondwana.
I know I keep writing about it, when discussing the origins of Australian plants, most recently with discussion of the Eucryphia trees of Robertson. And before that, when discussing the Proteaceous plants (Waratahs, Banksias, Hakeas and Persoonias, Grevilleas, etc.)
Well, the “boffins” tell me that before Gondwana was “Pangea”, a supercontinent which included Laurasia (basically the northern continents we know today) and Gondwana (basically the southern continents, plus India). This drawing comes from John W Kimball’s website called “Biology”.



Well I have found an animated image of the breakup of Gondwana, which shows 200 million years of the Earth’s surface movements in about 10 seconds. Cute. Better than that, you can run it backwards and forewards, and watch bits of the great gondwanan continent split off. The speed with which India breaks away and crashes into Laurasia, to create the Himalayas is quite striking.
So too is the yo-yo movement of Australia, first north, then south again, before heading relentlessly north again until it reaches its present position.




I invite you to go to this site and have a look. http://kartoweb.itc.nl/gondwana/gondwana_small.html

It requires the Macromedia “Shockwave Plug-in”, but this is available, free, from this site.
The part of this theoretical reconstruction which puzzles me most is that South America and Australia do not ever appear to have been close together, which makes their common heritage of plants, in the Proteaceae family, and also the Eucryphia genus more puzzling than I had first imagined. (They were, at some stage linked by that part of Gondwana which is now Antarctica.) None-the-less, I am not yet satisfied with my understanding of these early continental relationships.
I suspect that this is possibly a distortion introduced because of the somewhat arbitrary orientation of the “map” on which these maps are based. I would like to see a “globe” reconstruction, rather than a flat map, to see if these distortions disappear.

Tuesday, January 17, 2006

Persoonias puzzle the "Geebungophiles"

I went down along the Tourist Road this afternoon, to check for any less familiar Ground Orchids, but didn't find any. There were just a few stragglers of the Hyacinth Orchids still flowering.


However, the Persoonias are flowering now. They have tiny yellow flowers, but they are, for some reason, some of my favourite plants.


They are an odd bunch, within the Proteaceae Family. They have small, yellow flowers which are almost tubular in shape, which then open back with 4 symmetrical curled outer segments, leaving an inner tube which also curls back in 4 segments, leaving a "prominent style" protruding up the middle of the flower.


That "style" leads to the ovary. Like many of the Proteaceae, the "style" persists as a dried point protruding from the fruit or seed capsule. In the case of Persoonias, their fruit are small oval "drupes" - a fleshy fruit with a small hard stone inside it. Each has a small "point" which is the dried remains of that "style".


These fruits have a place in Australian literature, as they were called "Geebungs" by the early settlers (presumably derived from an Aboriginal word). They were, inadvertently, the source of the name of the "Geebung Polo Club", immortalised by A.B. "Banjo" Paterson.


In the sandstone country below Kangaloon, and Glen Quarry, one finds a number of species of Persoonia. The most obvious is P. levis, which has large flat leaves and a bright green colouration. Its colour makes it stand out amongst the grey-green colours of the Eucalypt forest. The next most obvious species is P. linearis, a tall shrub with soft, narrow leaves. It often has a weeping habit. Then, along the side of Tourist Road, where the original scrub has been slashed to create a fire break, one commonly finds re-growth of an interestingly "hairy" species, P. laurina, which has rusty-brown hairs all over it. Its new growth is tinged this rusty colour. Its leaves are soft, flat and oval shaped. A more unusual species is P. lanceolata
which has elongated oval leaves. *(Edit) There is also a closely related species, with a distinct bluish tinge to them. That is in fact Persoonia glaucescens a Federally Listed Vulnerable Species. At first glance it could be mistaken for a small Eucalypt.


The next two are oddities. Persoonias are either great hybridisers, or else, the Botanists cannot really make up their minds about them. Some Persoonias have a distinctive rolled-under edge to their leaves. One such species is P. hirsuta. (Ed: See Erratum comment below - this reference should be to P. mollis DJW 28.2.06) It is said to be "variable". That is an understatement. One I saw today looked like a scaled down version of P. linearis, with narrow leaves, but with the tell-tale rolled edge to the leaf. Around Carrington Falls (10 Km south-east of Robertson) the local P. hirsuta (?)
form there, (Ed: in fact, P. mollis. DJW 28.2.06) has oval or rounded leaves, half as long and twice as wide as this plant I was looking at today. Who is to know exactly what they are? I am far from confident of my identification of either of these forms of Persoonia.


Finally, there is a common prostrate Persoonia in the Kangaloon area. It forms bright green mats of foliage often more than a metre wide. Its leaf shape is almost diamond shaped, about 5 mm long, 3 mm wide. It does not meet the general descriptions of P. oxycoccoides, but that plant is the closest fit I can find. It is also described as "variable" in leaf form.


The fruit of the Persoonias are edible, but not very nice (to my taste). They have a sticky textured gummy flesh, with a hard stone, like a cherry pip, inside them. However, Gang Gang Cockatoos absolutely love these fruit. These birds will often sit quietly in a large Persoonia shrub, and will allow you to approach them, quietly, until they decide it is time to fly away, making their characteristic harsh creaking sound.

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