Branch (botany)

“ The body c has lost its leaves through some accident, and its growth has ceased. In other words, the parts at aaaa are like the shoot fh, except that they are shorter, and they are of the same age. One grew from the end or terminal bud of the main branch, and the others from the side or lateral buds. Parts or bodies that bear leaves are, therefore, branches.—The buds at bbbb have no leaves, and they remain the same [119] size that they were a year ago. They are dormant. The only way for a mature bud to grow is by making leaves for itself, for a leaf will never stand below it again. ”

“ From their situation they are out of ordinary sight; but they will well repay examination. For the vegetation that is carried on under ground is hardly less varied or important than that above ground. All their forms may be referred to four principal kinds: namely, the Rhizoma (Rhizome) or Rootstock, the Tuber, the Corm or solid bulb, and the true Bulb.
Fig. 97. Rootstocks, or creeping subterranean branches, of the Peppermint.
104. The Rootstock, or Rhizoma, in its simplest form, is merely a creeping stem or branch growing beneath the surface of the soil, or partly covered by it. ”

“ At the base of each branch an adventitious root may be formed from a cell immediately below the first leaf-sheath, but in aerial shoots the roots usually remain undeveloped. The lateral branches repeat on a smaller scale the general features of the main axis. In some species, the shoots are unbranched, and in others the slender branches arise in crowded whorls from each node. Leaves, roots and branches are given off in whorls, and the whorls from each node alternate with those from the node next above and next below. ”

“ Those living surfaces of the plant which are most exposed to light are green or highly coloured. The root tends to grow downward, but the stem tends to grow upward toward light [16] and air. The plant is anchored or fixed in the soil by the roots. Plants have been called “earth parasites.”
The Foliage Part.—The leaves precede the flowers in point of time or life of the plant. The flowers always precede the fruits and seeds. Many plants die when the seeds have matured. The whole mass of leaves of any plant or any branch is known as its foliage. ”

“ Any part of the stem may produce them, but they most readily come from the nodes. As a general rule they naturally spring, or may be made to spring, from almost any young stem, when placed in favorable circumstances,—that is, when placed in the soil, or otherwise supplied with moisture and screened from the light. For the special tendency of the root is to avoid the light, seek moisture, and therefore to bury itself in the soil. Propagation by division, which is so common and so very important in cultivation, depends upon the proclivity of stems to strike root. ”

“ The stem, when seen in transverse section, has its vascular bundles arranged in a ring; in reality, however, they form a kind of cylindrical network in the stem; the bundles are open, and thickening takes place by means of a cambium; annual rings are formed in the perennial stems. There is a rich and very varied form of branching. The two first leaves of a shoot (fore-leaves) are placed nearly always to the right and to the left; the same arrangement is found in the two first leaves developed on the flower-stalk, and these are, as a rule, the only two ”

“ They have hollow stems, with partitions at the nodes; the leaves consist only of a whorl of scales at each node, these coalescent into a sheath: from the axils of these leaf-scales, in many species, branches grow out, which are similar to the stem but on a much smaller scale, close-jointed, and with the tips of the leaves more apparent. At the apex of the stem appears the fructification, as it is called for lack of a better term, in the form of a short spike or head. This consists of a good number of stalked shields, bearing on their inner or under face several wedge-shaped spore-cases. ”

“ Branching.—The regular place from which a branch grows is the axil of a leaf, from what is called an axillary bud; but branches cannot grow in the axils of all leaves. A tree with opposite leaves occasionally has opposite branches; while a tree with alternate leaves has all its branches alternate.
Most branches continue their growth year after year by the development of a bud at the end, called a terminal bud. Many trees form this bud for the next year's growth so early in the year that it is seldom or never killed by the winter weather ”

“ Each leaf is traversed by two fibro-vascular bundles of entirely different structure from those of the ferns. Each is divided into two nearly equal parts, the wood (x) lying toward the inner, flat side of the leaf, the bast (T) toward the outer, convex side. This type of bundle, called “collateral,” is the common form found in the stems and leaves of seed plants. The cells of the wood or xylem are rather larger than those of the bast or phloem, and have thicker walls than any of the phloem cells, except the outermost ones which are thick-walled fibres like those under the epidermis. ”

“ In these the axis remains short, nearly as it is in the bud; the leaves therefore remain close together in sets or circles; the outer ones, those of the calyx, generally partake more or less of the character of foliage; the next set are more delicate, and form the corolla, while the rest, the stamens and pistils, appear under forms very different from those of ordinary leaves, and are concerned in the production of seed. This view gives to Botany an interest which one who merely notices the shape and counts the parts of blossoms, without understanding their plan, has no conception of. ”

“ Flowers collected in separate dense and spherical leafy-bracted heads, which are scattered along the summit of the stem; the upper sterile, consisting merely of stamens, with minute scales irregularly interposed; the lower or fertile larger, consisting of numerous sessile 1–2-celled pistils, each surrounded by 3–6 scales much like a calyx. Fruit wedge-shaped or club-shaped, more or less corky toward the summit, the hard endocarp perforated at the apex.— Rootstocks creeping and stoloniferous; roots fibrous. Stems simple or branching, sheathed below by the base of the linear leaves. ”

“ The roots of air-plants, such as certain orchids, draw their nourishment from the air.
The experiment of marking roots and stem has been already tried, but it should be repeated. Repetition of experiments is always desirable, as it fixes his conclusions in the pupil's mind. The stem grows by a succession of similar parts, phytomera, each part, or phyton, consisting of node, internode, and leaf. Thus it follows that stems must bear leaves. The marked stems of seedlings show greater growth towards the top of the growing phyton. It is only young stems that elongate throughout. ”

“ The plant may at once be recognized by the heart-shaped pods and small, white, four-petaled flowers. The plant begins to flower when very small, but continues to grow until it forms a much-branching plant, half a metre or more in height. On pulling up the plant, a large tap-root (Fig. 93, A, r) is seen, continuous with the main stem above ground. The first root of the seedling plant continues here as the main root of the plant, as was the case with the gymnosperms, but not with the monocotyledons. ”

“ But if a branch is bent over, or arched, the bud in the highest position will produce the strongest germ, and the rest will be weaker the nearer they approach the extremity. In horizontal branches the case is different. The buds on the upper side are generally stronger than those nearest the ground. ”

“ A flower-bud dies, when it has perfected its seed, like an annual plant, and hence requires no place on the bark for new roots to pass downwards; but on the contrary leaf-buds, as they advance into shoots, form new buds in the axilla of every leaf, which new buds require new roots to pass down the bark, and thus thicken as well as elongate the branch, now if a wire or string be tied round the bark, many of these new roots cannot descend, and thence more of the buds will be converted into flower-buds. ”

“ Displacement of the branches or of the floral-leaves sometimes takes place. The flowers are often red at first, and later on become blue or violet; they hardly ever have any smell. The fruit entirely resembles that of the Labiatæ, but the radicle of the latter is turned downwards. The fruitlets present small differences which have systematic importance; they are hollow or flat at the base, attached to a flat or columnar receptacle, etc.
1. Heliotropieæ. This group deviates from the characteristics mentioned above in the undivided ovary and terminal (“apical”) style. ”

“ Pod with evanescent partitions, and a thick axis bearing several anatropous seeds, 5-valved, the valves coiling elastically and projecting the seeds in bursting. Embryo straight; albumen none.—Leaves simple, alternate, without stipules, in our species ovate or oval, coarsely toothed, petioled. Flowers axillary or panicled, often of two sorts, viz.,—the larger ones, which seldom ripen seeds;—and very small ones, which are fertilized early in the bud; their floral envelopes never expand, but are forced off by the growing pod and carried upward on its apex. ”

“ Embryo thread-shaped, spirally coiled in the rather fleshy albumen, destitute of cotyledons, sometimes with a few alternate scales (belonging to the plumule) ; germination occurring in the soil.—Leafless annual herbs, with thread-like yellowish or reddish stems, bearing a few minute scales in place of leaves; on rising from the ground becoming entirely parasitic on the bark of herbs and shrubs on which they twine, and to which they adhere by means of suckers developed on the surface in contact. Flowers small, cymose-clustered, mostly white; usually produced late in summer and in autumn. ”

“ Everything was prepared, and even formed, beforehand: the short joints of stem in the bud have only to lengthen, and to separate the leaves from each other so that they may unfold and grow. Only a small part of the vegetation of the season comes directly from the seed, and none of the earliest vernal vegetation. ”

“ Each seed is a long club-shaped body, with a bulbous base and a slender point, more or less produced. While it yet hangs from the branch, the radicle and crown of the root begin to grow, and gradually lengthen, until the tip reaches the soil, which it penetrates and thus roots itself; while those which depend from the higher branches, after growing for a while, drop, and, sticking in the mud, throw out roots from one end, and leaves from the other. ”

“ Stems above ground, which is the most usual form for them, are of many kinds, all serving the purpose of support to the leaves and flowers, and as a means of carrying sap from the roots or underground stems to the upper part of the plant, and also to carry certain foods to the roots from the leaves, of which more anon. In the case of herbs, like goldenrod or daisy, the stem may be apparently all pith on the inside, with only a thin outer coating of harder substance, not unlike bark, but usually green. ”

“ V. Genus; VI. Species.
To illustrate: The white pine belongs to the highest great division (sub-kingdom) of the plant kingdom. The plants of this division all produce seeds, and hence are called “spermaphytes” (“seed plants”) . They may be divided into two groups (classes) , distinguished by certain peculiarities in the flowers and seeds. These are named respectively “gymnosperms” and “angiosperms,” and to the first our plant belongs. The gymnosperms may be further divided into several subordinate groups (orders) , one of which, the conifers, or cone-bearing evergreens, includes our plant. ”

“ These are outgrowths of the epidermis, or skin of the root, and increase its absorbing power. In most plants they cannot be seen without the aid of a microscope. Indian Corn and Oats, however, show them very beautifully, and the scholars have already noticed them in their seedlings. They are best seen in the seedlings grown on damp sponge. In those grown in sand, they become so firmly united to the particles of soil, that they cannot be separated, without tearing the hairs away from the plant. ”

“ The third difference is that, while the stem bears leaves, and has buds normally developed in their axils, roots bear no organs. The stem, however, especially when wounded, may produce buds anywhere from the surface of the bark, and these buds are called adventitious buds. In the same manner, roots occasionally produce buds, which grow up into leafy shoots, as in the Apple and Poplar. ”

“ It cannot be too strongly urged that the number of facts that the children may learn is not of the slightest consequence, but that the teacher should aim to cultivate the quick eye, the ready hand, and the clear reason.
The root of the Morning-Glory is primary; it is a direct downward growth from the tip of the caulicle. It is about as thick as the stem, tapers towards the end, and has short and fibrous branches. In some plants the root keeps on growing and makes a tap-root; in the Bean, it soon becomes lost in the branches. ”

“ Stem strictly erect from an annual root, and with the upright or ascending branches wing-angled or grooved; leaves alternate, linear, acute, the upper subulate and glandular-serrulate; a pair of dark glands in place of stipules; sepals ovate-lanceolate and sharp-pointed, strongly 3-nerved and with rough-bristly-glandular margins, scarcely longer than the ovoid-globose incompletely 10-celled pod; styles united almost to the middle.—Dry soils, E. Mass. to Minn., and southwestward.—Flowers and pods twice as large as in the preceding. ”