Vegetative propagation

“ This family of plants possesses seed-vessels which remain firmly shut on their contents while the soil is hot and dry, and thus preserve the vegetative power intact during the highest heat of the torrid sun; but when rain falls, the seed-vessel opens and sheds its contents just when there is the greatest probability of their vegetating. In other plants heat and drought cause the seed-vessels to burst and shed their charge. ”

“ In the first place, the enormous holdfast, ensured by the millions of points of adherence, enables the plant to withstand even powerful lever actions from above, and provides fixed points against which the root-tips can work as they drive deeper into the soil. In the second place, the intimate contact of the root-hairs and particles of soil, ensures that the films of water held by surface-action on the soil-particles and root-hairs shall be in continuity with the water saturating the cell-walls of the latter, and therefore with the protoplasm and cell-sap in their interior. ”

“ Meanwhile, as the subterranean shoots increase in number, the older ones, connecting the successive growths, die off year by year, liberating the already rooted side-branches as so many separate plants; and so on indefinitely. Cutting these running rootstocks into pieces, therefore, by the hoe or the plough, far from destroying the plant, only accelerates the propagation; it converts one many-branched plant into a great number of separate individuals. ”

“ The nature of the vegetation supported by the soil is of paramount importance in relation to phytophagous organisms, and examples need scarcely be instanced of certain species of soil insects being dependent upon the presence of their specific food plants. ”

“ Should the soil of fields or greenhouses be much colder than the air, the plant suffers. When in a warm atmosphere, or in a dry atmosphere, plants need to absorb much water from the soil, and the roots must be warm if the root-hairs are to supply the water as rapidly as it is needed. If the roots are chilled, the plant may wilt or die. ”

“ As a rule, it is not desirable to have either seeds or seedling plants in the ground for any length of time when the temperature is too low for active vegetation; for while they rest, other, lower organisms (fungi and bacteria) , adapted to low temperatures, may continue in full activity at the expense of the vitality of the crop plant. ”

“ The root-fractured herbaceous plants repairing the injury almost immediately, and before the rudiments of the reproductory parts have time for expansion, the greater quantity of moist nourishment afforded by the unsought newly stirred soil, produces a flush of radical leaves, which react to further the extension of the roots. ”

“ Active motion, local and general, though usually of relatively small amount, accompanies all plant-growth. Throughout root, stem, leaf, and flower transference of material is going forward vigorously. The root hairs and stomata are working at high pressure; the chlorophyll never ceases its activities while daylight lasts. Externally, the growing branches, leaves, and flowers also display incessant movement, sweeping the air in small circles, or in the case of climbing plants in curves of considerable amplitude. ”

“ It has no need of leaves to carry on the process of making food. Some parasites with green leaves, like the mistletoe, take the crude sap from the host-plant and assimilate it in their own green leaves. Plants that are nourished by decaying matter in the soil are called saprophytes. Indian Pipe and Beech-Drops are examples of this. They need no green leaves as do plants that are obliged to support themselves. ”

“ We have now glanced at the most distinctive of the plant formations which we meet with in our own country, and find that they accompany extreme conditions relating to water and soil: it remains to return to the consideration of the vegetation which develops under conditions of a more normal character—on ordinary soils, in fact, which are neither very wet nor very dry. ”

“ This excessively lively habit is, no doubt, directly caused by the conditions of life; the sterile soil and scanty vegetation of the region it inhabits require in a species going in large bodies, and subsisting exclusively on fallen seed, a greater activity than is necessary in the rich fertile region further north. ”

“ If we have a tree growing on a hillside in a soil that easily transmits moisture and it gives that tree constantly a stream of pure water going through its root system, and there happens to be enough fertility in that vicinity, that moisture is impregnated with plant food, and the tree will get all it wants. ”

“ If you go along the lanes and in the gardens in the height of summer when it is hot and dry and the sun beats on the plants all day, you may see them beginning to wither for want of water. The roots are not able to find enough moisture in the soil to supply the leaves, which, being in the hot air, continue to transpire away the water resources of the plant, so that in the end each of its cells must suffer and the whole become limp and droop. ”

“ The heat of the sun’s rays, which is intended by nature to warm the soil, will be expended in evaporating the water from its surface; and thus the plants will never receive that genial warmth about their roots which so much favours their rapid growth. Where too much water is present in the soil also, that food of the plant which the soil supplies is so much diluted, that either a much greater quantity of fluid must be taken in by the roots,—much more work done,—or the plant will be scantily nourished. ”

“ The principal causes which enable a certain assemblage of plants thus to maintain their ground against all others depend, as is well known, on the relations between the physiological nature of each species, and the climate, exposure, soil, and other physical conditions of the locality. Some plants live only on rocks, others in meadows, a third class in marshes. Of the latter, some delight in a fresh-water morass,—others in salt marshes, where their roots may copiously absorb saline particles. ”

“ Plants of dry habitats can increase their absorption only by modifying the root system so that the absorbing surfaces are carried into the deep-seated layers of soil, and the surfaces in contact with the dry soil are protected by means of a cortex. Exception must be made for epiphytes and a few other plants that absorb rain water and dew through their leaves, and for those desert plants that seem to condense the moisture of the air by means of hygroscopic salts, and absorb it through the epidermis of the leaf. The storage of water in the leaf is a very important device ”

“ In all these circumstances, therefore, there exist the most advantageous conditions for the rapid and continuous growth of vegetation, and, judging from the fossils thereof, it must have gone on with a density and luxuriance that wellnigh surpasses conception. Floating vegetables first made their appearance, spreading their branches and leaves on the surface of the water, and filling the basin or lagoon with their débris thus forming a support for the more aërial vegetation, compared with which anything in our day of the same species, in respect to size and quantity, fades into insignificance. ”

“ Ground that has not been disturbed for some hundred years, on being ploughed, has frequently surprised the cultivator by the appearance of plants which he never sowed, and often which were then unknown to the country. The principle has been ascertained to be capable of existing in this latent state for above 2000 years, unextinguished, and springing again into active vegetation, as soon as planted in a congenial soil. ”

“ In these cases the whole surface is not at once overspread with plants, but a gradual progress of vegetation is traced from the accidental introduction of a single seed, perhaps, of each species, wafted by winds or floated by currents. The remarkable limitation of certain species to single spots on the globe seems to favor the supposition of specific centres. ”

“ And, besides, we have found varieties of the same kind or species of tree, some of them adapted to prosper in dry air and soil, and others in moist air and soil. Although the above causes prevent a positive limitation of certain kinds of trees to certain soils, yet there are some which have superior adaptation to moist soils and others to dry; some whose roots, from their fibrous soft character, can only spread luxuriantly on light, soft, or mossy soils, and others, whose roots have power to permeate the stiffest and most obdurate. ”

“ Within this paved area not a blade of any green thing is allowed to grow, except a single species of grain-bearing grass. Having planted this crop in a circle around, and two or three feet from, the centre of the mound, the insect tends and cultivates it with constant care, cutting away all other grasses and weeds that may spring up amongst it and all around outside of the farm-circle to the extent of one or two feet more. ”

“ This prevents the damping off of the seedlings, to which they are very liable when treated otherwise; it also greatly facilitates their growth and the formation of roots, the soil being so perfectly open that it is readily affected by the atmosphere, and thus kept in the most favourable condition for promoting vegetation. ”

“ A small portion of air to be admitted on fine days, to purify the atmosphere of the house. Keep the surface of the soil in the pots free from weeds, as also from moss and lichen; but when doing so do not loosen the soil so as to injure the roots near the surface. Keep every plant free from dead leaves, and all climbing plants neatly tied up. The Achimenes, Clerodendrons, Erythrinas, Gloxinias, and the various bulbs will now be approaching a state of repose, and therefore will require but little or no water. ”

“ In considering the alga-flora of a soil it is necessary to distinguish between two very different sets of conditions under which the organisms may be growing. In the first place, they may grow on the surface of the soil, being subjected directly to insolation, rain, the deposition of dew, the drying action of wind, relatively quick changes of temperature and other effects of climate. ”

“ Soon the ground is green with mosses and liverworts and dotted with small fungi, making the first crop of the season. Then the grass leaves weave a new sod, and the exceedingly slender panicles rise above it like a purple mist, speedily followed by potentilla, ivesia, bossy orthocarpus, yellow and purple, and a few pentstemons. Later come the daisies and goldenrods, asters and gentians. Of the last there are three species, small and fine, with varying tones of blue, and in glorious abundance, coloring extensive patches where the sod is shallowest. ”

“ It is quite certain, that if a healthy seed, or leaf-bud, be placed in such a situation, that, according to the laws known, it will in all likelihood germinate, if all the elements for its sustenance exist in the soil, and the temperature and hygrometric {144}condition of the atmosphere are adapted to it, a healthy plant will be the result. ”

“ After these different soils have been brought under cultivation, the characteristic species, which we have just enumerated, disappear, and are replaced by other plants, which grow, to all appearance, spontaneously, under the name of weeds; but, in reality, spring from germs or seeds too frequently mixed up with the different manures, or spread abroad by the agency of birds or the wind. ”

“ In many cases such epicormic shoots are stimulated to grow out by suddenly exposing an old tree to more favourable conditions of root-action and assimilatory activity, owing to the felling of competing trees which previously hemmed it in from light and air, and restricted the spread and action of its roots in the soil. ”

“ The vital career of the annual water plants closes with the formation of the seed. They die and fall into decay through the agency of the water bacteria, whose activity carries their substance on to renewed life in the circulation of matter. The vegetation of most of our northern perennial water plants is interrupted during the winter. Some of them, like the pond lily, have long rootstocks, in which superfluous food is deposited as in a storehouse in the course of the summer, to serve in the spring for the formation of the new leafy growth ”

“ There must, as in the wind-carried pollen, be a tremendous wastage, yet sufficient quantities of it do fertilize the females, particularly in the ditch grass, which fruits very freely.
Whether it be any of the various contrivances for insect fertilization, or by the winds, or, as in the eelgrass, by the water, the climax of the flower’s life is always reached in this act. For all annuals the plants, also, begin to die down then, a process that is completed with the production of seed, which is, of course, the object of all those varied modes of fertilization. ”

“ When a single plant once gets root-hold in pasture land, it spreads with amazing rapidity, damaging and crowding out the grass in all directions, so that whenever and wherever it appears its utter and thorough extirpation, whatever the labour and cost, should be insisted upon with the least possible delay. When plucked by the hand the plant emits a fœtid, sickening smell, all trace of which is only effaced from the fingers by a very thorough washing indeed. ”

“ But the quantity of leaves which annually falls has also much influence upon the extent to which the soil is capable of being improved by any given species of tree, as well as the degree of rapidity with which those leaves, under ordinary circumstances, undergo decay. The broad membranous leaf of the beech and oak decay more quickly than the needle-shaped leaves of the pine tribes, and this circumstance may assist in rendering the larch more valuable as a permanent improver. ”