NEW ENGLAND FARMER. 



399 



For the New England Farmer. 



AGRICULTURE— NO. 2. 



HISTORY OF VEGETATION. 



BY R. H. HOWARD. 



We find the primal starting point in the history 

 of vegetation to be the commit ling of the seed to 

 the soil, wherein it is ultimately to develop itself 

 in all its parts, and wherefrom it is principally 

 to derive its nourishment till maturity. 



In this, as in all other developments of nature, 

 we find that the future growth and health of a 

 plant is very much, yea, almost wholly dependent 

 upon tlie manner in which the seed is primarily 

 brought to develop itself. Hence great care must 

 of needs be taken that it be properly committed to 

 its appropriate element. In this operation we 

 must first take heed that the seed be not buried too 

 deep — that is, not so far under but that the air can 

 have access, as this is absolutely necessary to 

 germination. The earth, therefore, must lie loose 

 and light over it in order that the air may pene- 

 trate. Henc3 the importance of digging, harrow- 

 ing, plowing, &c. A certain degree of heat and 

 moisture, such as usually takes place in spring, is" 

 likewise necessary. 



But before we proceed farther, in order that we 

 may more fully understand the nature of germina- 

 tion, let us glance at the different parts of which 

 the seed is composed. 



The external covering or envelope is found to 

 contain, besides the germ of the future plant, the 

 substance which is to constitute its nourishment — 

 called the parenchyma, {a.) 



The seed is generally divided into two compai-t- 

 ments, called lobes or cotyledons (h.); the dark col- 

 ored kind of string which divides these lobes is called 

 the radicles (c), as it forms the root of the plant. The 

 figure and size of the seed depend very much upon 

 the cotyledons; these are said to vary in dilTerent 

 seeds, and it is plainly seen that while some have 

 only one, as wheat, oats, barley and all the grasses, 

 others have three, and some six. But most seeds, 

 as for instance all varieties of the bean, have but 

 two cotyledons. 



When the seed is buried in the earth above 

 about 40°, it imbibes water, which softens and 

 swells these lobes; it then absorbes oxygen, which 

 combines with some of its carbon, and is returned 

 in the form of carbonic acid. This loss of carbon 

 increases the comparative proportion of hydrogen 

 and oxygen in the seed, and excites the saccharine 

 fermentation, by which the paranchymatous matter 

 is converted into a kind of sweet emulsion. In this 

 form it is conveyed into the radicle by vessels for 

 that purpose, and in the meantime the fermentation 

 having caused the seed to burst, the cotyledons are 

 rent asunder, the radicle strikes into tlie ground 

 and becomes the root of the plant, and hence the 

 fermented liquid is conveyed to the plumu/a, {(1.) 

 This is a substance enclosed within tlie lobes of the 

 cotyledons and contiguous to the radicle — from 

 whence the stem aiises — whose vessels have been 

 previously distended by the heat of fermentation. 

 The plumula being thus swelled, as it were, by the 

 emulsive fluid, raises itself and springs up to the 

 surface, bearing with it the cotyledons, which, as 

 soon as they come in contact witli the air, spread 

 themselves and are transformed into leaves, which 

 at first appear very thick and clumsy. This is 

 owing to their retaining the remains of the paren- 



chyma, with which they still continue to nourish 

 the young plant; as it has not yet sufficient roots 

 and strength to provide for its sustenance from the 

 soil. But when it has arrived at a little greater 

 age, and the radicle shall iiave sunk somewhat 

 deeper into the earth, sending out its fil)rous shoots 

 in every direction, each of which is found to be 

 furnished with an apparatus for sucking up nourish- 

 ment from the soil, the function of the original 

 leaves being no longer required, they gradually de- 

 cay, and the plumula becomes a regular stem, 

 which, through a regular process of development, 

 is now prepared to increase to the full stature of a 

 mature plant. 



Here we can but note a very striking analogy 

 between the seed and the egg: both require an 

 elevation of temperature to be brought to life, both 

 at first supply with aliment the organized being 

 which they produce, and as soon as this has at- 

 tained sufficient strength to procure its own nour- 

 ishment, the egg shells break, whilst in the plant 

 the seed leaves fall off. 



Likewise another analogous principle of the 

 vegetable and animal kingdoms we shall observe 

 as we progress — viz, that as in both cases, the chief 

 and original nourishment is derived from the soil, 

 so from \\\e at inospherc is derived their principle of 

 vitality. But how is this? plants do not breathe ? — 

 We shall see. 



As soon as the young plant feeds from the soil 

 and provides for its sustenance "on its own hook," 

 it requires the assistance of leaves, by which or- 

 gans the plant throws off its superabundance of 

 fluid. This secretion is much more abundant in 

 the vegetable than in the animal creation, and the 

 great extent of surface is admirably calculated for 

 carrying it on in sufficient quantities. This fluid 

 thus transferred is found to consist of little else 

 than water. The sap by this process is converted 

 into a liquid of great consistence, which is fit to be 

 assimilated to its several parts. Hence the great 

 injury arising from destroying the leaves of a plant, 

 as it not only diminishes this transpiration, but 

 also the absorption by the roots: for it is ascer- 

 tained that the quantity of sap absorbed from the 

 soil is alwa'ys in proportion to the quantity of fluid 

 thrown off by the transpiration. We see, then, the 

 necessity of a young plant unfolding its leaves as 

 soon as it commences deriving its nourishment 

 from the soil. 



Perhaps it would be proper to remark here that 

 the function of transpiration seems to be confined 

 to the upper surface of the leaf. Whilst, on the 

 contrary, the lower surface, which is somewhat 

 more rough and uneven, and furnished with a kind 

 of hair, or down, is destined to absorb moisture 

 and other such ingredients as the plants derive 

 from the atmosphere. 



As soon as the plantmakes its appearance above- 

 ground, light, as well as air, also becomes necessary 

 for its preservation. We often observe what a 

 predilection vegetables seem to have for light, 

 which IS especially essential to the development of 

 colors and to the thriving of the plant. 



But to proceed more directly to the connexion or 

 relation rather of the atmosphere to vegetation, we 

 might with some propriety observe that plants are 

 truly endowed with the property of breathing, as 

 they certainly do derive many principles or pro- 

 perties from that source, and also yield others to it, 

 but during this process of respiration — if thus it 



