Plant stem

“ The foundation of a new plant consists equally of a stem and leaves, and the sole distinction is that the stem becomes intimately blended at its base with the mother plant in its growth, and has no free radical extremity like that exhibited by a plant developed from a seed. ”

“ So that the two chief duties of stems are to act as supports for the leaves and flowers, and to carry the food materials and water between the roots and leaves.
Just as we found in the case of the roots, there are many extra duties which the stems may take over, and as a result, we find great variety in the appearance of stems. For example, in some plants the stem does not grow up into the air at all, but creeps along just below the surface of the ground. ”

“ The Stem is the axis of the plant, the part which bears all the other organs. Branches are secondary stems, that is, stems growing out of stems. The stem at the very beginning produces roots, in most plants a single root from the base of the embryo-stem, or caulicle. As this root becomes a descending axis, so the stem, which grows in the opposite direction is called the ascending axis. Rising out of the soil, the stem bears leaves; and leaf-bearing is the particular characteristic of the stem. But there are forms of stems that remain underground, or make a part of their growth there. ”

“ The flower-stem is more than 2 ft. high, and very much branched; the branches commencing at from 4 ins. to 8 ins. above the ground, and forming a large and exceedingly handsome panicle of flowers of a light-blue colour, tinged with the greyish hue of the numerous membranous bracts and thin dry calyces. A well-drained, sandy soil, in an open sunny position, is the best for this plant, which, however, grows in any ordinary garden-soil, and is admirably adapted for naturalisation or grouping with the acanthuses, tritomas, etc., the effect of the inflorescence being very remarkable. ”

“ The most prominent of these parts are root, stem, leaf, flower, fruit, and seed. Familiar plants differ wonderfully in size and shape,—from fragile mushrooms, delicate waterweeds and pond-scums, to floating leaves, soft grasses, coarse weeds, tall bushes, slender climbers, gigantic trees, and hanging moss.
The Stem Part.—In most plants there is a main central part or shaft on which the other or secondary parts are borne. This main part is the plant axis. Above ground, in most plants, the main plant axis bears the branches, leaves, and flowers; below ground, it bears the roots. ”

“ The gardener imitates them in the process called layering, that is, bending down an erect branch and covering it with soil, causing it to strike root. When the connecting stem is cut, a new plant is formed. Long and leafless stolons, like those of the Strawberry are called runners. Stems creep below the ground as well as above. Probably the pupil will think of some examples. The pretty little Gold Thread is so named from the yellow running stems, which grow beneath the ground and send up shoots, or suckers, which make new plants. ”

“ Away up amongst the branches and foliage far above one's head, leaves and flowers are developed on numerous branches which have vigorously pushed out as soon as they got near the sunlight, this tough, spiny, thread-like stem being their only connexion with the ground.
The development of these climbing plants is probably connected with the dense shade of forests. In such places a young stem growing up will become long and drawn out; its tip will droop over and hang downwards. But there is a curious peculiarity in the growth of all stems. ”

“ When living tree seeds are exposed to proper amounts of moisture, warmth and air in a fertile soil, they will sprout and grow. A root develops which pushes its way down into the soil, while the leaf-bud of the plant, which springs from the other end of the seed, works its way upward toward the light and air. This leafy part of the seed finally forms the stem of the tree. But trees may produce plenty of seed and yet fail to maintain their proper proportion in the forest. ”

“ When you study the botany that is written for older people, you will find that plants are set apart in separate groups, according to the number of their seed leaves.
Strange though it may seem to you, plants with but one seed leaf have certain habits that you will not find in a plant with two seed leaves; and a plant with two seed leaves, long after these have passed away, will show by root and stem that it had more than one seed leaf. ”

“ Contrast between Stem and Root. Stems are ascending axes; roots are descending axes. Stems grow by the successive development of internodes (13) , one after another, each leaf-bearing at its summit (or node) ; so that it is of the essential nature of a stem to bear leaves. Roots bear no leaves, are not distinguishable into nodes and internodes, but grow on continuously from the lower end. They commonly branch freely, but not from any fixed points nor in definite order.
69. Although roots generally do not give rise to stems, and therefore do not propagate the plant, exceptions are not uncommon. ”

“ Even a very slender stem can convey a vast amount of water and food to a plant which is transpiring or growing actively, as we can test roughly by weighing a pot shrub as it begins to come into leaf, and again a week later, or comparing the growth of a pea with the size of its stem at the base. ”

“ As the roots are feeding and storing places, so the stem is a sort of passage way for the passing back and forth of liquids. Take a stem of a big plant, like an oak tree, and you see in the wood where storage of fibre has gone on. ”

“ Once it finds itself firmly rooted in the stem of its victim, it begins to grow vigorously. With every few inches of its growth it sends new roots deep into this stem. And when it feels quite at home, and perfectly sure of its board, it begins to wither away below, where it is joined to its earth root. Soon it breaks off entirely from this, and draws every bit of its nourishment from the plant or plants in which it is rooted. ”

“ In general, we do not see much of the stem because it is largely hidden by the covering of leaves, so that if you want to study stems you should go to the woods in the winter when there are no leaves on the trees, and you can see the form of the branches themselves. ”

“ Growth from the Seed. Phanerogamous plants grow from seed, and their flowers are destined to the production of seeds. A seed has a rudimentary plant ready formed in it,—sometimes with the two most essential parts, i. e. stem and leaf, plainly discernible; sometimes with no obvious distinction of organs until germination begins. This incipient plant is called an Embryo. ”

“ The sensitive plant has indigestible seeds—so they say—and it will flourish for ever. I give my advice thus to a young plant—have a strong root, a weak stem, and an indigestible seed; so you will outlast the eternal city, and your progeny will clothe mountains, and the irascible planter will blaspheme in vain. The weak point of tuitui is that its stem is strong. ”

“ And when a stem on land knows how to keep off meddlers, yet has the wisdom not to take unnecessary trouble when afloat, like that of the amphibious knotweed, then we feel that a plant gives its stem, as well as its other parts, a large supply of common sense. ”

“ Success with these plants may be secured by first selecting a sheltered and warm position, so that their noble leaves may be well developed and not lacerated by storms when they are fully grown; secondly, by giving them a deep, free, and thoroughly-drained soil; and thirdly, by confining them as a rule to a simple and rather dwarf stem, so that the vigour of the individual may not be wasted in several branches. The effect of a plant kept to a single stem, as shown in the plate, is always much superior to that of a branched one. Young plants present this aspect naturally ”

“ Others are just appearing above the earth.
Here is a young morning-glory (Fig. 120) . We see that its stem, like that of the bean, was the first thing to come out of the seed. This stem has turned downward into the earth. From its lower end grows the root, which buries itself deeper and deeper.
[Pg 113]
An older plant shows us that the upper part of the stem straightens itself out and grows upward, bearing with it a pair of leaves (Fig. 121) .
Fig. 120
From between these starts a tiny bud, that soon unfolds into a fresh leaf, which is carried upward by a new piece of stem. ”

“ By confining it to a single stem and using it in a young state, you get the fullest size and grace of which the leaves are capable. Allow it to become old and branched, and it may be useful, but by no means so much so as when young and without side branches. It may be raised from seed as easily as a common bedding plant. ”

“ In the first place, the sun warms the ground in which the seed lies buried. Then the seed swells and bursts, and sends downward a little root; the root drinks in the water from the soil, and so gets larger, and spreads around; and by-and-by it sends up a stem above the ground. As soon as the sunlight falls on the little plant, it gets stronger, and is able to take food as well as drink from the soil, so as to get its full shape and size and green color. ”

“ The stem is lost in the branches. The apple tree, plum (Fig. 58) , maple, elm, oak, China tree, are familiar examples. Deliquescent means dissolving or melting away.
Each kind of plant has its own peculiar habit or direction of growth. Spruces always grow to a single stem or trunk, pear [52] trees are always deliquescent, morning-glories are always trailing or climbing, strawberries are always creeping. We do not know why each plant has its own habit, but the habit is in some way associated with the plant’s genealogy or with the way in which it has been obliged to live. ”

“ In this country it is seldom seen more than 10 ft. high. The stem is tree-like, simple or divided at the top, and often, when old, becoming{127} much branched, each branch terminated by a crowded head of lanceolate-linear entire leaves of a glaucous green colour. The flowers form a large terminal panicle, and are individually small and of a greenish-white colour. This plant is more graceful and effective when in a young state, in which it usually occurs in our gardens, than when old and branched. ”

“ You know that they are stowing away their food in warmer, safer places than can be supplied by the delicate leaves. And when all the food has been drawn out of the leaves, and packed away in the right spots, then the plant finishes a piece of work it began some time before. This piece of work is the building-up of a row of little cells just where the leafstalk joins the stem or branch. When this row is complete, it acts almost like a knife, loosening the stalk from the stem. ”

“ And the reason why they set several together is that a plant that grows from one only is weak. The roots which grow from these seeds become entangled together and so do the first shoots from the very start, so that they combine to make a single stem. ”

“ And these are connected with the stems of branching shrubs through infinite varieties of structure, in which the first steps of transition are made by carrying the cluster of radical leaves up, and letting them expire gradually from the rising stem: the changes of form in the leaves as they rise higher from the ground being one of quite the most interesting specific studies in every plant. ”

“ In a vigorous plant, the lower leaves are about twenty inches in length, and from three to five in breadth, decreasing as they ascend. The inflorescence, or flowering part of the stem, is terminal, loosely branching in that form which botanists term a panicle, with long, linear floral leaves or bractes at the origin of each division. ”

“ Take the little seedling by the stem between thumb and forefinger, and with a small round pointed stick or dibber, or with the forefinger of the other hand, make a hole to receive the roots and about half the length—more if the seedlings are lanky—of the stem. As the seedling drops into place, the tips of both thumbs and forefingers, by one quick, firm movement, compress the earth firmly both down on the roots and against the stem, so that the plant sticks up firmly and may not be readily pulled out. ”

“ Stems are of Many Forms.—The general way in which a plant grows is called its habit. The habit is the appearance or general form. Its habit may be open or loose, dense, straight, crooked, compact, straggling, climbing, erect, weak, strong, and the like. The roots and the leaves are the important functional or working parts; the stem merely connects them, and its form is exceedingly variable. ”

“ Then the plant has no stem, or an underground one. But if the three leaves rise above the ground, as in Fig. 17, they must reach their roots by elongating their stalks, and this elongation is the stem of the plant. If the outside leaves grow last, and are therefore youngest, the plant is said to grow from the outside. You know that 'ex' means out, and that 'gen' is the first syllable of Genesis (or creation) , therefore the old botanists, putting an o between the two syllables, called plants whose outside leaves grew last, Ex-o-gens. ”

“ Nodes and Internodes.—The parts of the stem at which buds grow are called nodes or joints and the spaces between the buds are internodes. The stem at nodes is usually enlarged, and the pith is usually interrupted. The distance between the nodes is influenced by the vigour of the plant: how?
Fig. 59.—Rhizome or Rootstock.
Stems vs. Roots.—Roots sometimes grow above ground (Chap. VII) ; so, also, stems sometimes grow underground, and they are then known as subterranean stems, rhizomes, or rootstocks (Fig. 59) .
Stems normally bear leaves and buds, and thereby are they distinguished from roots ”