Thea Render 1.5 Crack.epub
Ainoha Sistek
During the winter nearly all leaves are folded in various ways in a budfor protection from the elements. Nature shows herself in some of herwisest moods in the selection of methods to accomplish this. In somebuds, notably those of the horse-chestnut, the bud is coated with asticky substance to protect the tender young leaves inside. In othersthere is a hard outer coat, as in the hickory, impregnable to the mostdriving sleet, others again have the leaf rolled so tightly and pointedso sharply at the end, as in the beech, that water cannot cling to thebud nor soak in, until the warmth of spring gives the signal for theannual miracle of the bursting out of foliage. Leaf buds are sometimeshard to find on certain plants, as they are formed at the base of aleafstalk and covered by it during the growing season. It is only as theleaf falls in the autumn that the hollow base of its stalk is seen tohave hidden during the summer the young bud for the following season.The plane tree or sycamore is a good example of a plant where no leafbuds can be found until the falling of the leaves in autumn.
Where the fruits are neither barbed nor very good to eat, and soapparently doomed to be more or less permanent stay-at-homes, nature hasprovided some of them with the proper equipment for flight through theair. Winged fruits like the maple are to be seen on any windy day duringtheir season scurrying before the breeze, and consequently spreadingtheir kind over considerable distances. In the maple there are twowings, joined at the base where the seeds are embedded in the wings, andthe fruit is known as a samara (Figure 58), or key fruit, from aslight resemblance to an old-fashioned key. Ash trees bear fruits thatare a slight modification of this type and may be carried considerabledistances by the wind (Figure 59).
This green coloring matter or chlorophyll is perhaps the most importantsubstance in nature. Without it all except a very few plants would die,and even in those beautifully colored leaves like coleus or caladiumchlorophyll is always found, but in these colored leaves it is merelyobscured by other coloring substances. It is in the chlorophyll that theability resides to take the inorganic substances through the roots orfrom the air, and by the aid of sunlight transform them into organicsubstances like starch and sugar. Nothing else in all nature can do it;without this faculty, which the commonest green leaf possesses, theearth would prove uninhabitable within a single year. Just whatchlorophyll is chemically is not yet thoroughly known, but the thing ofchief interest is that it is hardly ever found in parts of the leaf notexposed directly to the sunlight, and that during the autumnal coloringand before the fall of the leaf chlorophyll is carried to other parts ofthe plant, and quite possibly stored for use the following season.
But water cannot stay in this condition of pressure and stagnation foreven a brief period. That would be as if a leaf were like a toy balloonwhich, after inflation, had the entrance pinched and so remainedinflated. And while we have all along spoken of factories for makingsugar, and pressure pumps for forcing up food and water, it must neverbe forgotten that this marvelously adjusted mechanism is a living thing.Constantly growing, even producing their own means of falling in theautumn, leaves must be thought of as living machines, just as we arestill more highly developed machines. In other words the accumulatedwater in the cells of the leaf must be removed, after it has served itsuse, and replaced by fresh supplies. The removal is carried on by itsevaporation into the halls, or, in the more precise terms of our accountof leaves as factories, into the intercellular spaces. It will berecalled that these are connected with the outside air through the poresor stoma. When the air outside is hot and dry it might easily suck outby evaporation all the water vapor in these intercellular spaces andwilting follow at once. This would actually happen if the guard cells,already mentioned, were not constantly on the job. They control the sizeof the opening just as certainly as a steam valve does, and maintain,with a few exceptions, just the proper amount of water loss not only tomaintain turgor, but to see to it that transpiration, as this process iscalled, goes on rapidly enough to insure fresh supplies of water beingsent to the leaf. The opening and closing of the stoma by the guardcells is a nicely balanced operation dependent upon root pressure,turgor, and atmospheric conditions. Guard cells have, because of this,been much studied in spite of the fact of their microscopic size. We nowknow that they allow greater openings during the night and reduce themduring the day. When we reflect that the constant removal of water inthe leaf, both as such, and as the only carrier of food supplies from the roots, depends in suchlarge measure upon the functioning of these guard cells, then we come tosome realization of their importance to the plant.
Two of the very largest plant families, not so far mentioned in thisaccount, depend almost absolutely upon insects. In the daisy family,with over eleven thousand members, the large heads of flowers, oftencontaining scores of individual flowers, are constantly brushed, overand over again, by the pollen-coated bodies of insect visitors. And inall or nearly all orchids (Figures 73-75), comprising over five thousandkinds, the same process is accomplished. In these plants, in fact, theact is, if possible, more
In our ordinary discussions or gossip of neighbors or relatives, theabsolutely necessary starting point is to know their name. Theiracquirement of this by christening, or by the adoption of it through theusage of parents, settles for life what they will be called. Plants arealso christened, and that ceremony is one of the most important eventsin our subsequent discussion of them.
There are many other foods derived from plants, besides all the fruitsand vegetables too numerous to be noted in detail here. One fact ofsignificance seems to stand out from a study of the uses of plants byman. There are three distinct regions from which the great bulk of ourfood and many other useful plants have apparently come. One is the areaof which Indo-China is approximately the center, and which is theancestral home of rice, the banana, tea, sugar cane, and many othervaluable plants. Somewhere in this southeastern corner of Asia theremust have been a highly developed agriculture which rescued these plantsfrom the wild, and from which they have spread throughout the world. Thesecond region, somewhere near Mesopotamia, appears to be the cradle ofwheat and a few other useful plants. And the third region is the westernpart of America from southern Mexico to northern Chile, where corn,tobacco, the pineapple, sweet potato, potato, the red pepper, and thetomato were all discovered with the discovery of this continent.
The thing for which we drink tea is an alkaloid in its leaves that ispleasant to the taste and refreshing to the senses. It is released inboiling water in a very few minutes, but if tea is allowed to stay inwater longer than this, tannic acid is also released. This is asubstance found in the bark of certain trees and is used in tanningleather. As 10 per cent of the leaf of tea consists of this substance itmay readily be seen how easily improper methods of making tea willrender it not a refreshing and delightful beverage but an actual poisonto the digestive tract.
There are several different kinds of commercially important cottons, andperhaps dozens of others, all derived from the genus Gossypium, arelative of our common garden mallows belonging to the Malvaceæ. Byfar the most valuable is Sea Island cotton, derived from Gossypiumbarbadense, which is probably a native of the West Indies, althoughreally wild plants are yet to be discovered. It is the kind, of whichscores of varieties are known in cultivation, that is grown mostly alongour southeastern coastal States. Next in value, but cultivated ingreater quantity because larger areas are suited to it, is Gossypiumhirsutum. The fiber is a little shorter, but the total amount of cottonderived from this species probably exceeds that from all other kinds. Itis the cotton grown mostly in upland Georgia, Louisiana, and Texas, andthe wild home of this species is supposed to be America, although it,too, has never been found in the wild state. The third cotton plant isGossypium herbaceum, a native of India, and the origin of manyvarieties now grown in that country. It has a shorter fiber and is worthabout one-third the price of Sea Island cotton. From Abyssinia andneighboring regions comes the fourth important cotton plant, Gossypiumarboreum, differing from the others in being a small tree. All theothers are shrubby, while G. herbaceum is merely a woody herb. Thesedifferent plants have been tried in the countries suited to cottonraising, but, generally speaking, the chief crop from each is producedin the country nearest the supposed wild home of it.
The Carboniferous age of fern, cycad, and conifer ancestors was by nomeans a quiet, orderly period, as from geological evidence it appears tohave been much subject to alternate emergence and submergence of great tracts of land. Compared withwhat followed, it actually was a period of comparative quietness,however, and it must, in at least most parts of the world, havepermitted the slow development of certain of its plant groups to a stateof perfection never reached since. This is particularly true of theancient relatives of our club mosses and horsetails.
There remains still another type of variability which has been noticedfrom very early days, and received the name sport, because quitesuddenly, from a crop of otherwise similar specimens, one or a fewplants showed marked and permanently transmitted differences from theaverage condition. Such sudden offshoots, which occur rather frequentlyin many plants, are known as mutants, the process as mutation. Hugo deVries, a Dutch botanist of world-wide fame, was the chief modern figurewho drew attention to mutants, and explained how they differ fromfluctuating variants in that while these tend to revert to the averageor mass conditions the mutant, once it appeared, held true to type. Awell-known example of mutation is the cabbage, brussels sprouts,cauliflower, and kohl-rabi, all of which are sports or mutants from aweedy seaside plant of the mustard family, native in Europe. Sincetheir appearance, hundreds of years ago, they have held their essentialcharacters. If they had been environmental variants they would in allprobability have reverted to their weedy ancestor. Hundreds of sports ormutants have been recognized and isolated, so that many of our mostvaluable garden plants have arisen through this ability of plants tovary in often sudden and rather startling degree. The gardener andhorticulturist, from long observation and a keen sight for valuablenovelties, have always known that sports are fruitful sources of newforms of plants, but De Vries first scientifically studied them andworked out the principles by which they apparently react. The cause ofthem is still unknown.
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