Stem (fungus)

“ Forms of Stems.—Stems may grow in many ways. Let the pupils compare the habits of growth of the seedlings they have studied. The Sunflower and Corn are erect. This is the most usual habit, as with our common trees. The Morning Glory is twining, the stem itself twists about a support. The Bean, Pea and Nasturtium are climbing. The stems are weak, and are held up, in the first two by tendrils, in the last by the twining leaf-stalks. ”

“ 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. ”

“ The generic characters of the first three species may be stated as follows:
Stems dichotomous, with rudimentary subulate leaves, sometimes obsolete in terminal branchlets and fertile branches; and in decorticated specimens represented only by punctiform scars. Young branches circinate. Rhizomata cylindrical, with circular root-areoles. Internal structure of stem, an axis of scalariform vessels enclosed in a sheath of imperfect woody tissue and covered with a cellular bark more dense externally. Fruit, naked sac-like spore-cases, in pairs or clusters, terminal or lateral. ”

“ 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 ”

“ Stem ascending from a creeping base, rigid, very branching, invested by the bases of the leaves and stipules; leaves crowded in two ranks, recurved-spreading, narrow-lanceolate or linear (3–5 ́ long and 2–3 ́ ́ wide) , acuminate, ciliate-serrulate with translucent teeth, many-nerved; stipules obtuse when young, their nerves soon becoming bristles; spikes numerous, loosely few-flowered, on short peduncles ”

“ 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. ”

“ Having determined these facts, a study should be made of the arrangement, form, structure, color, and the cell contents of the different cells in order to determine the species of plant from which the stem was obtained.
HERBACEOUS STEMS
The great variation in the structure of herbaceous stems is shown in the cross-sections of spigelia (Plate 95) ; in ruellia (Plate 96) ; in the charts of powdered genuine horehound, powdered spurious horehound, and in the chart of powdered insect flower stems. ”

“ STEMS AND SEED LEAVES The smaller plants usually have green stems. The larger ones have brown, woody stems, such as you see in bushes and trees; for the trunk of the biggest tree in the world is nothing but a great stem.
The delicate green stems die down to the ground during the cold winter. Sometimes the whole plant [Pg 120] dies, the root below as well as the stem above ground. But often the root (or what we usually call the root) lives, and sends up a fresh stem the next year. ”

“ But the whole plant, often many feet in length, consists only of single gigantic cells. A tough skin incloses its juices, which flow in a continuous stream through the stem, leaves, and roots of the curious growth, here taking up through the skin and assimilating mineral substances, there producing and transforming organic matter, and at the same time advancing the growth and increase of the whole. Not less peculiar than the inner structure and appearance of the stem is the form of the leaves of water plants. Their service to the organism is the same with that of the leaves of other plants. ”

“ 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 ”

“ The essentials of flowers are stamens and pistils, giving rise to seeds, and the essential of a seed is an embryo (8) . Cryptogamous or Flowerless plants are propagated by Spores; and a spore is not an embryo-plantlet, but mostly a single plant-cell (399) .
483. Vascular Cryptogams, which compose the higher orders of this series of plants, have stems and (usually) leaves, constructed upon the general plan of ordinary plants; that is, they have wood (wood-cells and vessels, 408) in the stem and leaves, in the latter as a frame work of veins. ”

“ Stem slender, often flexuous, 1–3° high, less leafy, bearing few or several heads on divergent peduncles; leaves obovate to ovate or oblong-lanceolate, narrowed at base and ciliate, the midrib hairy beneath; scales more imbricated, thicker and more obtuse; pappus more rigid. ”

“ The branched filamentous rhizoids which spring from the lower region of the stem also correspond to protonemal branches. The structure of both stem and leaf reaches a high grade of organization in some mosses. Not only are thick-walled sclerenchymatous cells developed to give rigidity to the periphery of the stem and the midrib of the leaf, but in many cases a special water-conducting tissue, consisting of elongated cells, the end walls of which are thin and oblique, forms a definite central strand in the stem. ”

“ Stem composed of a ground-mass of soft tissue (parenchyma) in which bundles of wood-cells are irregularly imbedded; no distinction into wood, pith and bark. Leaves usually parallel-veined, mostly alternate and entire, commonly sheathing the stem at the base and often with no distinction of blade and petiole. Flowers mostly 3-merous or 6-merous. ”

“ The flowering plants have several distinct and visible organs for the formation and fertilization of their seed, to each of which is assigned a special and necessary office. In the flowerless section, on the contrary, there are none of these visibly separate agencies in reproduction, and what are usually termed the seeds do not show any parts representative of the developed product. In the true seeds, which belong to flowering plants alone, are contained the rudiments of a stem, leaves, and root, but in the spores of the flowerless plants nothing of the kind is found. ”

“ The internal structure of the stem, and the character of the seed-vessels, shew them to have been a link between single-lobed and double-lobed plants, a fact worthy of note, as it favours the idea that, in vegetable, as well as animal creation, a progress has been observed, in conformity with advancing conditions. ”

“ Stems or branches which remain under ground give out roots as freely as roots themselves give off branches. Stems which creep on the ground most commonly root at the joints; so will most branches when bent to the ground, as in propagation by layering; and propagation by cuttings equally depends upon the tendency of the cut end of a shoot to produce roots. Thus, a piece of a plant which has stem and leaves, either developed or in the bud, may be made to produce roots, and so become an independent plant. ”

“ Each of these cells can act as a separate plant, drinking in the water and air it needs, and feeding and growing quite independently of the roots below. Yet at the same time the moss stem has a great advantage over single-celled plants in having root-hairs, [Pg 88] and being able to grow upright and expose its leaves to the sun and air. ”

“ Stem simple, black-spotted; leaves of three kinds; floating ones becoming very large (41⁄2 by 31⁄2 ́) , roundish-ovate and cordate or ovate-oblong, 25–37-nerved, all alternate; upper submersed ones (3–5) usually lanceolate, acute at base and very long-acuminate, 10–15-nerved, very thin, cellular each side of the midrib, undulate, short-petioled; lowest (2–4 near the base of the stem) thicker, plane, oval or oblong with a rounded base, or spatulate-oblong, on longer petioles; stipules rather short and obtuse; peduncles thicker than the stem ”

“ By their more rapid growth than the stem, they reach above the growing-point, and, folding over each other, cover it more or less completely. As the stem elongates, the leaves upon the older portion are gradually separated, and an ordinary stem, with its leaves arranged at regular intervals, results. A bud is simply a young stem, with its undeveloped leaves. A developed stem is a series of similar parts, those parts being a leaf with a portion of the stem above and below it, each borne upon its predecessor, and in turn bearing the next one in the series. ”

“ 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. ”

“ The stem is more widely differentiated, and throughout its structure a rapid passage of fluid takes place. It has the power of absorbing moisture from the atmosphere, so that if a plant be placed dry in a glass of water with its rosette of leaves hanging over the edge, it acts like a syphon, and the water will drop from it until the glass is emptied. ”

“ 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. ”

“ 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. ”

“ Stem about two feet in height, generally erect, but, as the seeds approach maturity, often acquiring a drooping habit; stem-leaves more finely cut or divided than those proceeding directly from the root, and all possessed of a strong and somewhat disagreeable odor. ”

“ 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. ”

“ When alive they are filled with cell sap and protoplasm.
Trace the woody strands through the nodes. Do they ascend vertically? Do they curve toward the rind at certain places? Compare their course with the strands shown in Fig. 70. The woody strands consist chiefly of tough fibrous cells that give rigidity [61] and strength to the plant, and of long tubular interrupted canals that serve to convey sap upward from the root and to convey food downward from the leaves to the stem and the roots. ”

“ When the growth of a seed begins to be developed, the germ, from which the stem originates, shoots forth under the form of a delicate curved fibre, which, gradually bursting its covering, makes its appearance at the end of the seed. ”

“ The Veil or collar about the stem is as variable as fashion—thick and closely woven or flimsy as gossamer, or vanishing as the plant grows old. The 56Stems may be even as a lead pencil, or swollen like a pen-holder, or bulbous toward the base, or distorted by pressure in the tufts. It is as variable in color as the cap, usually darkening downward in hues of brown. The outside is firm and fibrous, sometimes furrowed, inside soft or hollow. ”

“ Pubescent; stem prostrate, rooting at base; leaves short-petioled, obovate-elliptical or wedge-oblong, obtuse, serrate; racemes densely many-flowered; pedicels shorter than the calyx; capsule obovate-triangular, broadly notched.—Dry hills and open woods, N. Eng. to Mich., and southward. July. (Eu., Asia.)
V. Chamæ̀drys, L. Stem pubescent, at least in two lines, ascending from a creeping base; leaves subsessile, ovate or cordate, incisely crenate; racemes loosely-flowered; pedicels little longer than calyx; capsule triangular-obcordate.—Sparingly introduced into Canada, N. Y., and Penn. ”