Part 2

But what is this soft white wood next to it?

This is the _Alburnum_, or white wood. When you tap a tree, the sap comes from this part. Now watch what is coming.

I see--the Liber is separating from the soft Alburnum, and there comes a sticking substance of sap oozing between them. What is that?

It is the _Cambium_, or _Albumen_; the white of egg is albumen. Look again.

Ah! the cambium is softening the cellular tissue that bound the liber to the alburnum, and while that is growing outward, I find that the other parts are growing upward.

Let us take a peep at the leaf buds. You see they feel the growing influence, and are letting fall bundles of woody matter, which pass into the cambium, and become attached to the liber. The cellular tissue passes in the mass around, along the medullary rays, and a new substance becomes attached to the liber.

But that new substance is another alburnum, father, and our old alburnum is turned a quite hard wood.

You see, then, that while the last year’s soft wood becomes a hard ring or layer, another is formed in its place alongside of the liber. The hard wood is dead compared with the softer kind.

I think I understand that. But where does the nourishment come from?

The sap when first rising is watery and nearly colourless. But after exposure to air and light in the leaf, and losing much water in evaporation, it becomes thicker, and, descending by the bark, is prepared, like blood, to renew and to form different parts of the structure.

Is there any other movement of the fluids of a plant?

Yes, there is a true circulation in the interior of all the cells.

Does a tree form a fresh ring of wood every year?

This depends upon the character of the tree. Some trees take many years in forming it.

How is it that the layers of our Gum tree are not equal in thickness?

That is influenced by the season. One year it was very cold or dry, and the tree made little wood. Another season, the rain was abundant, and the sun did his work well, and so the _concentric_ or ring-like layer was fuller.

But I see that on one side of the tree, the bands are thinner than on the other.

That was the side that received the cold wind. The greater the number of leaf-buds above a part of a stem, the greater the diameter.

How does the bark manage when the tree forms new wood, and presses against the liber?

The outer bark cracks and peels off. When the bark grows, it does so internally; a new liber appearing adjoining the layer of new alburnum.

What connection, father, has grafting trees with growing?

The gardener takes a bud of one fruit-tree, and applies its liber, the life part, to the liber of the stock of another tree, binds them together, and puts clay outside to exclude the air. The nature, then, of the bud is communicated to the tree; the juices will be altered, and another fruit produced.

Well, thank you kindly, dear father. I do feel that I know something now about a tree growing. I can tell, too, why a tree does better in one place than another, making more wood and leaves. It is when it can find in the soil a sufficient amount of food, in the carbon, lime, phosphorus, sulphur, potash, and the like.

Quite right, and some other day we may have a talk about the varieties of manures, and the way of tilling the soil, especially in relation to Australian farming. But it is now time for us to return home. So come along, my boy.

* * * * *

It was not until a few days had passed, that Willie’s father was at leisure to give another lesson. During that interval the boy had not been idle. He had roamed over the Bush, and stored up lots of specimens of the vegetable world. There were many varieties of roots in one place, and of bark in another. He had cut open many a plant to try to observe some of the peculiarities of which his father had told him. The leaves being so perishable, rather bothered him in his researches, till his mother showed him how to preserve them, by placing them between sheets of blotting or other soft paper, and changing the wrapper occasionally. Willie himself was astonished at his collection, and greatly surprised at the many kinds of leaves he had obtained. Having some notion of drawing, he set about copying a few of the most curious forms, especially in cases where he thought the pressure would spoil the appearance. His good father, as you may be sure, was quite delighted at his son’s industrious research.

One thought had all this while very much perplexed our young friend. He had a fair notion of the causes of the growth of a tree after it had begun to grow; that which puzzled him was, how the tree arose from a seed, and how the seed itself was produced. He unburdened his mind to his father.

To describe this subject, said the father, I must give you the history of a flower.

I used to think, father, that the flowers were only formed to please our eyes, and yet I knew the seeds had something or other to do with them.

You are partly right. There was no reason for flowers to be pretty, any more than for butterflies. But it has pleased God to put the beautiful along with the useful. He has thus adorned this world for our home, that his creatures may be the happier in it. You have doubtless observed that flowers are as various as leaves.

I have done so, and I remarked that the same sort of plant always produced the same kind of blossom, year after year, just as birds lay certain eggs of their own sort only. How is this?

No one can answer that question, except by saying that God has established fixed laws, according to which everything acts in order. The planets turn round the sun, the sun appears every morning; plants and animals produce their like, and everything that God has made moves in its proper path.

Except men and women, father. And yet I think if stars and flowers know and do their duty, we should be at least as good as they.

Now for the flowers, Willie. What do you see in them?

There are the pretty leaves, the common-looking green leaves outside of them, and a lot of things standing upright in the middle of the flower.

Your pretty leaves are the _Corolla_ of the flower; the green ones form the _Calyx_; and the standards inside are _Stamens_ and _Pistils_. We will take one at a time, and begin with the Calyx, although that, and the Corolla too, may be wanting in a plant, as they are not really necessary.

It seems as though the Corolla took care of the Stamens, and the Calyx protected the Corolla.

You are not far from the mark, my boy. But can you tell me whether the Corolla of a flower is always in one piece or not?

I should think not. I recollect some flowers with one pretty cup all round, while others are made up of a great many coloured leaves.

You must call those leaves _Petals_. Some plants have four petals in the form of a cross. Did you ever notice a pea blossom?

Yes, father, and thought it a funny one.

Just gather one and examine it. How many petals are there, and how are they placed?

There are five, but not all of the same size. There is a good upper one, two side ones, and two at the bottom, enclosing the rest of the flower.

That upper one is the standard, and the two at the sides are the wings. Could you describe the orchis, the wild flower of our bush?

I will try. There are six petals; three are bent backward, two are at the sides, and one opposite to the three is also bent backward. Is not honey found at the bottom of the corolla cup?

It is, in a place called the _Nectary_. I shall afterwards explain the object of the sweets. But we must hasten on to the _Stamens_. These generally arise from near the base of the petals.

Are they the ones with the yellow dust on the top?

They are, my lad. If you look at one, you will find a long thread or _Filament_, bearing a loose top, called the _Anther_, which carries the _Pollen_ or yellow dust.

But why is not the pollen always to be felt on the anther?

Because it is shut up in cells at first. When the walls of these burst open, the pollen shows itself outside, and is also scattered about.

As things alter so strangely under the microscope, father, how would our dust look there?

No two plants have the same shaped pollen, which is of all possible forms. The tiny grains are generally each enclosed in a delicate bag, the subtle powder of which is more like smoke than anything else, in which are particles of starch or drops of oil.

But our orchis does not seem to have a regular anther, for the pollen looks all of a heap.

That is correct. But which do you fancy is the _Pistil_?

I don’t know, unless it be that in the middle surrounded by the stamens. This is a thread, too, with a knob at the top.

The support is the _Style_, and the summit is the _Stigma_. When you examine flowers you will observe the stigma of various shapes and sizes; but there is always a sticky substance on the top. Does the pistil rise from the same place as the stamens?

No, it comes from a lump at the bottom.

That lump is the _Ovary_, or seed basket, sometimes known as the _Germen_. Some botanists believe that the several parts of flowers are only metamorphosed, or changed leaves, and that the pistil is one of these growing vertically. You have seen in a double stock, or other double flower, that the stamens have grown into petals.

But why is it that the corolla falls off so soon? I have seen our garden beds strewn with blossoms, and yet the stamens and pistils keep on much longer.

But what happens when these go in their turn, Willie?

Why, the ovary, as you call it, swells out. But what makes the fruit?

That fleshy substance around the seeds, of which you are so fond, is merely the swollen _Pericarp_, or covering of the seed vessel. Children’s teeth should not go into the pericarp until the seeds are about ripe.

I know that. When a pear is nice and mellow, then the seeds within are quite hard. But would you call the pod of the pea a pericarp?

Certainly. It consists of two valves, with hinges, and the seed on each side. Sometimes there are several valves together, and we call the whole a _Capsule_. When these burst, the seeds fall out.

But how are the seeds produced?

We are coming to that next. I told you of the bursting of the anther, and the scattering of the pollen. Though much of the dust is wasted, a part is caught on the glutinous stigma of the pistil.

And what becomes of it then?

It passes down the hollow style into the ovary at the bottom.

Yet I have seen flowers in which the pistil was higher than the stamens; how could the pollen reach it?

Many curious contrivances effect the transfer. The wind blows the yellow dust. A bird throws some about. An insect catches some on its wings and legs, and stepping on the stigma, leaves pollen behind.

Is the honey in the nectary to tempt the insects to the flower?

The sweet morsel attracts birds as well as insects.

When, then, the stamens have discharged their pollen, and the pistil conveyed it to the germen, I suppose there is no further use for them.

There is not, and they die off like the petals of the corolla and the calyx before them. But because of the variety of stamens in number and situation, botanists have thought it well to divide plants into classes by this means.

How do they do that, father?

They place in one class all vegetable substances whose flowers contain but one stamen; in another, those with two stamens; and so forth. The number and arrangement of the pistils enable us to form plants into orders; as, a flower may have four stamens, and one pistil, or four stamens and two pistils, &c.

I suppose the stamens and pistils are always found together.

No, they are not: though Compound flowers are made up of sets of flowers within the same calyx, we have plants in which the stamen, or male flowers, are in one part, and the pistil, or female flowers, on another portion of the tree. The former are barren flowers; the latter, fertile or fruitful, as the seed vessel is only connected with the female side.

I think the service of winds, insects, and birds, is more needful than ever now. But I have seen people pick off flowers from melon and cucumber plants, saying, that they were no good.

These were the male blossoms. But they who pluck off all the barren blossoms before the pollen appears, can never expect to have fruit; for the fertile blossoms are of no use without the others. But what would you think of male flowers being all on one tree, while the female are upon another at a distance?

I suppose that is to give the birds and insects more work than ever. Please tell me a tree that has this curious plan.

The Palm is an instance. Where the trees grow in a cluster, as they usually do, there is no difficulty. If very far apart, the male blossoms, when ripe, are cut off, carried to the other tree, and the pollen shaken over the pistil flowers.

That is singular. But how do water plants get on with the yellow dust?

Some of them rise to the surface to flower, and sink to seed. Those that keep below are provided with a glutinous pollen, which cannot be affected with the wet.

* * * * *

Well, father, I do think we are getting on bravely with our lesson. But I would so like to peep into the germen or ovary, and see what goes on there.

We will do so. I ought to have said, that before the pollen sheds, the ovary has a lot of half formed seeds adhering to the _Placenta_ inside. These _Ovules_, as they are called, are a sort of nucleus or kernel, and are each placed between two sacs of open mouths.

What goes into those mouths?

Nothing goes in, but the pollen of the stamens comes down through them out upon the ovule, and is received to its _Embryo_, or heart, through a very small hole. Soon after the pollen has entered, the ovule becomes perfected and vivified, or made full of life.

And is that the seed?

The ovules do then become seeds in their little cells, and are, in their turn, shed out when ripe.

But do they turn into real seeds directly the pollen gets down?

By no means. Nourishment and time are necessary to growth and change. I must explain further about the seed. Beneath the _integument_ or covering of ordinary seeds, as a pea, what do you observe, Willie?

I have seen the two halves of the seed show themselves, when the skin breaks, and the plant seems to grow from between them.

Your two halves are the _lobes_ or _cotyledons_ of the seed. These fleshy substances enclose the _embryo_, from which the leaves and roots proceed. The upper part, from which the leaves arise, is the _Plumula_, or _little plume_, or feather. That from which the rootlet proceeds is the _Radicle_, or root part: sometimes it is called the _Rostellum_, or _little beak_.

Of what use are the cotyledons, father?

They supply nourishment to the central portion, which is to develop the plumula and rostellum, and thus surround them. A sort of passage of communication exists between them. There is, also, a neck between the plumula and rostellum.

What is that scar upon the seed?

The point at which it was attached in its vessel.

Well, now I think I really do understand all the mysteries of tree growing. Like as a young animal suckles its parent until strong enough to manage other food, so does a young plant depend upon the cotyledon for provision, until its rootlets are able to search the soil, and leaflets absorb from the air.

I trust, my boy, that while you admire the order and adaptation, you will acknowledge Him whose wisdom planned the whole, whose power performed it, and whose goodness makes it serve the happiness of His creatures.

* * * * *

A few days after the last conversation, Willie went with his father into the Bush among the mountains. The way was long, and the track was rough, but various things occurred to make the journey pleasant. The Laughing Jackass gave the boy a merry greeting, a snake peeped at him slyly among the long grass, and then brushed off quickly to its hole. A Porcupine raised up its quills as he passed, and then trotted off to the scrub. But the trees,--the trees! How tall they were! How thick they were! With the help of their handkerchiefs, Willie and his father measured the girth of some, and found them thirty, forty, and even fifty feet round. Most of the Stringybark and Gum trees ran up straight as a dart, fit to thrust into some monster ship for a mast. Then the sweet-scented shrubs on every side, the green Myrtle, the pyramidal and beautiful Sassafras, and many others, seized upon the boy’s imagination, until he came to a place that made him stare, and then caper about like a Black fellow at a corrobory. What could it be?

A break in the tangled brush underwood had given him a peep down into a valley that seemed prettier than anything he had read of in a fairy tale. There was no rough rock, but a floor of soft moss. The most musical of rippling creeks trickled along the vale. No other sound was heard, for the very birds seemed afraid to disturb with their joyous notes the silence that dwelt there. There were no Gums, no Wattles, rising from this moss bed. Instead of these, Willie saw a lot of very odd looking trees. They were not very tall, for they rarely rose above 12 or 15 feet. The bark was unlike anything seen elsewhere. There were no branches, but at the top of the straight stem were several branch-like leaves, 8, 10, and 12 feet long, with such a graceful bend towards the valley. At the top of the stem, rising up from the place where the leaves sprang out, was a curious curling piece, with little shoots. The valley was full of these wonderful vegetable festooned pillars.

Oh! Father! father! cried the boy, what are those beautiful trees down there? I never saw any like them before.

They are Fern trees, my lad. Walk over and look closely at them.

Willie trod upon the soft carpet, and thought it damp, as well as soft. The air, too, was so close, and felt so cold and raw, that he lost half his pleasure already. He could not help saying so to his father.

Ah, my boy, said he, you are not the first to find nice things having something disagreeable about them when approaching nearer to them. Remember, that while roses have thorns, pleasures will have their drawbacks.

Yes, I know I am often very tired after a pretty ramble, and rather queer after a pasty.

True enough; there is only one place where happiness brings neither fatigue nor surfeit. But let us see what is the difference between one of these Fern trees and one of your old companions, a Gum tree.

I can tell. One is like a tree with branches and so forth; but the other is not. Then the bark is quite different. I can see that the leaves of the Fern tree are like those of the common Fern, which is so troublesome in our sandy land, only they are a great deal larger.

But there is a stranger difference still. Just take my axe and cut one of them down.

I can soon do that. It is not nearly so thick as that Wattle I fetched down the other day with not a dozen cuts.

Willie doffs his jacket, catches at the axe, and is at once dropping it in double quick time upon the Fern stem. A dozen blows were given, and another, and another, but the tree did not fall. Taking breath, and wiping his forehead, Willie murmured out:--

Well this is tough! it beats my Wattle, hollow. I declare if the axe don’t ring against it as if it were iron or glass. It is quite different from one of our trees, for that is rather soft at the outside, though it may get harder as we get towards the middle.

As I think you are more likely to blunt my axe, than cut down the tree, you may put on your jacket, and we will inspect that fallen fern I see yonder. Perhaps after you have looked at the inside, you will find another wonder.

It was not long before our young Botanist uttered an exclamation of joyful surprise.

I have found it out, said he. Only fancy, father, I was hammering away at a mere shell, though it was a hard one. The tree is quite soft inside, though like flint outside. It is the very opposite to every tree I ever saw before in all my life.

No doubt it is; and it was to see it with your own eyes that I brought you here to the Fern tree valley.

Thank you, dear father, you always like to give me a treat, and this is a rare one, too. But I am sure that such a tree as this could never grow like a vegetable Gum tree, that you were telling me all about.

Can you name any plants, Willie, of which the fern tree puts you in mind?

I know of none, unless it be the Bamboo, for that is hard outside and hollow within, and it seems, like this, to grow up straight about the same thickness throughout.

There is another tree of this character which we have in Australia, some kinds of which grow in other countries, producing dates, of which boys are so fond.

Any one can guess that:--it is the Palm. But whence have we Palms, father?

There are some in Gipps’ Land, at the foot of the Australian Alps; other finer ones are at Illawarra, south of Sydney; but more northerly, in the hotter parts, Palms are very common.

Is that one from which we get our Cabbage Tree Hats?

It is so. The head of the Cabbage Palm is so good tasting and nourishing, that many trees were felled on purpose to get at this sort of cabbage, especially in the early days of the New South Wales Colony.

Then Palms, and Bamboo, and Fern trees grow the same way, as their stems look the same, and as they have neither branches nor solid timber. But how do they grow, father? There is no new wood formed outside the last ring, as in the Gum tree.

It so happens, my boy, that new layers are formed for a while, inside instead of outside. Our new class of trees are, therefore, called _Endogenous_, from their growing internally, in opposition to the ordinary forest trees, which are _Exogenous_, from growing externally.

I suppose the new shoots arise from where we see the joints in the cane; but where is the fruit of our new Endogenous friend?

Have you never seen the pictures of bunches of dates and other fruits all among the leafy branches at the top?

Eh! that I have, with the figures of Blacks climbing up the long poles to get at the fruit.

Now I have two more hard words for you to learn, to distinguish our two sorts of trees. We know them not merely by the difference of wood, but of seed. First tell me how many cotyledons or lobes are in a seed?

There are two in all the seeds that ever I saw.

What! was that cocoa nut the same which you bought the other day?

No, that was all in one piece.

True, Willie; and you may recollect something about a date stone.

I do, indeed; that was single also. I see I must not be so sure another time about what I know. Now I understand. Our new friends of the hard shell stems, which bear fruit at all, have seeds of one piece instead of two.

Quite so. Now a plant of one cotyledon in its seed, is said to be _Monocotyledonous_, while that having two lobes is _Dicotyledonous_; _mono_ meaning one, and _di_, two.

Then my Gum tree, and Rose tree, and Sweet Pea, are all Dicotyledonous; but the nice Date Palm, the pretty Orchis, and the sweet Cocoa-nut, are Monocotyledonous. But are there any plants which are neither one nor the other?

There are some whose seeds are not to be distinguished, and are known as _Acotyledonous_, or _without cotyledons_. Can you not name one?

I don’t know, unless you mean such as the Ferns, the Mosses, and the Lichens on the rocks or decaying timber.

They are the very ones. We have now had examples of the three great varieties of vegetation; _Monocotyledonous_, having one lobe to the seed; _Dicotyledonous_, having two lobes; and _Acotyledonous_, without any.

Will you now, dear father, explain the way in which the Monocotyledonous plants differ from the Dicotyledonous, especially in their system of growth?

I will, my boy, and we will begin this time with the seed.