Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/67

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■brandies of trees, as foon as they have affixed themfelves, and being then in a ftate of drawing nourifhment, they will affix themfelves to the tree, and from its juices begin to thrive immediately.

It has been very naturally fuppofed by tho'e who thought the Mifletoe no perfect plant, that it had no roots, nay even thofe who allowed it ,to be a perfect plant, and produceable from feeds, yet have fuppofed it had no root. Malpighi, however, af- firms that he plainly faw its roots. And Tournelort counte- nances the fame opinion ; but neither of thefe authors have perfectly defcribed them.

In that part of the branch of a tree where the Mifletoe grows, there is always obferved a thicknefs, and the bark is always chopped in feveral places ; but the roots of the Mifletoe are by no means to be feen externally, being bid both by the bark of the tree, and by the expanfion of the bark of the plant itfelf at its bottom. It is neceflary, therefore, for the difcovery of the roots, to raife very nicely both the bark of the plant, and that of the tree i but the hardnefs of thefe barks, and their ftricr attachments to the roots, makes this difficult ; and there is indeed no way of fucceeding well in the attempt, but by boiling the part in water, and making nice diffeciions of it be- fore it is cold. By this means the bark of the Mifletoe, and that of the tree, are both eafdy raifed^ and the roots of the Mifletoe are found partly inferted into the bark, and partly into the wood of the branch.

The bark of trees is a fubftance compofed of feveral beds or flrata, the upper of outer of which is an extremely thin one, and the others, which are thicker, are formed by the exten- sion of the woody fibres; which run longitudmally into a fort of network, the cells of which are filled with a parenchyma- tous fubftance. This is the ft.rucr.ure of all the barks of a tree, except the outer thin one ; but of thefe, thofe are always the moft fucculent and rich which He innermofti or ncare'ft the wood of the tree.

It is obfervable, that when an infedl wounds the bark of a tree or plant, there is always a greater derivation of the juices to the wounded part than elfewhere, and hence galls and other protuberances are formed ; this feems alfo the cafe here, and the application of the trunk of the Mifletoe fced, ami the pene- tration of its roots feem alfo to wound the part fo much, as to caufe in the fame manner a derivation of a great quantity of juices for the nourifliment of the young plant : And as the roots ftrike deeper in, there is made a greater extravafation of the juices of the tree, arid a furt of tumoUr is neceflarily formed.

Among tlie feveral roots of the Mifletoe, there are fome which extend themfelves among the more fucculent parts of the bark, and others which penetrate to the wood of the branch. Thefe fpread themfelves every way with great eafe, as they are principally formed at a time when the tree is full of fap.

It has been fuppofed by many, that the roots of the Mifletoe penetrated the woody fubftance of the tree ; but though ap- pearances make greatly for this fyftem, it is by no means true in fail. The roots of the young plants, when they have penetrated through all the lamina of the bark, and reach the wood, turn off, as the roots' of plants do which meet with Hones, t&'c. in their paflage, and fpread horizontally between the inner bark and wood, or elfe re-afcend the bark, the loofe and juicy nature of which is much fitter for affording them nourifhment than the hard fubftance of the wood; It is true, that in making feclions of the branches where old plants of Mifletoe growj thefe are often found roots, nay fume times even the woody Item of the plant plunged into the matter of the hard wood ; but this is merely owing to the inner bark of the branch having become woody fmce the penetration of the roots, not to the roots finding their way into what was a&ual wood at the time.

I hereare alfo found always a multitude of woody excrefcences, like warts and wens, about the place where the Mifletoe grows i thefe are formed like the woody galls produced on trees by the punctures of infefts, by an extravafation of the woody juices. Thefe make the fwelling about that part of the branch where the Mifletoe grows, and thefe, a5 they become^ woody, and fwell about the roots, ferve to cover them with hard Wood, which they never penetrated. Thefe make it probable enough that the roots of Mifletoe never pene- trate bard wood ; but what proves it much more evidently, is, that if the branches of trees full of Mifletoe plants be cut and fplit in different dire&ions, juft at the place of the infertion of the plant, the feveral annual circles of the wood within are found perfeft, regular, and in their natural ftate, fo far as the branch was form'd at the time the Mifletoe took foot upon it ; thefe ihew the age of the branch at that time, but above thefe there^are always feveral other lamina:, which are what have been formed fmce the time of the Mifletoe^ growing there ; and thefe which have been formed out of the inner lamina of the bark, in which the roots of Mifletoe had made many wounds and great extravafations of the juices, arc found, tho' woody full of the roots of the plant, and are very irregular, and full of the tubera which thofe extravafations occafion, by by no means appearing like the annual circles of the wood formed before. The ligneous fibres in the outer, or fmce iuTpi,, Vol, II,

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form'd wood, are laid in very irregular directions, and the roots of the Mifletoe may be eafdy diftinguifhed among them by their colour.

The Mifletoe, as the bark in which its roots were fpread, hardened into wood, would be in the flate of a tree, planted in an earth which, by degrees, petrified about it, and rm,ft penfh ; but nature has provided for it in this cafe ; for as thefe foots are imprifon'd in wood* and a new bark is formed by the lap of the tree* the trunk of the Mifletoe fends out a new feries of roots, which fpread thro' this in like manner ; fothat tho' a plant of Mifletoe has ever fo many feries of its roots embodied in the hard wood, from which it can have no nourifhment, it has alfo fome, fufficient for its fupporr, fpread among its yet new-form'd bark.

The Mifletoe is frequently found in this ftate; nor are we to fuppofe, indeed, that tho' the wood is not able to furnifh fo much juice as the bark, that it furnifhes none at all ; for the roots of the plant do not decay, when they have penetrated what afterwards becomes perfect wood ; even in its hardeft ftatej they are ftill found perfect in it, and in a living ftate, and undoubtedly furnifti fome, tho' not a great deal of nou- rifhment to the plant. Another thing very remarkable in thofe plants of Mifletoe, many of the roots of which are lodged in the hard wood, is, that the roots diffufed through the" bark have often a large tubercle at their ends, which probably is furnifhed with numerous openings for the receiving the juices the plant is to be nourifhed by, and ferves in the place of many roots.

There are fometimes indeed found plants of Mifletoe which live wholly by the nourifhment they receive from the wood ; thefe are in the ftate of grafts of common fruit-trees ; but thefe are rare, and it very feldom fucceeds when the Mifletoe is at- tempted to be propagated by the common method ot grafting, though the plants of Mifletoe may very eafdy be grafted by approach into one another.

A farther circumftance worthy obfervatioil, is, that tho' fome plants of Mifletoe have been found growing very well with their roots only in the wood, yet this is generally fatal to them, and many plants of it are found dead and wither'd, by means of the woody part of the tree rifing into a fort of wen or tubercle about them, and by its clofcly fufrcunding their ftalk, pre- venting all intercourfe with the bark, by means of new roots. This is ufually the cafe when the plants of Mifletoe are weak" and the branch on which they grow very ftrong and vigorous \ and oh the contrary, when the plants are very ftrong, and the branch weak ; in which cafe, the roots of a large A, ijetoi plant will fometimes penetrate the whole round of the bark and taking in all the nourifhment to itfelf, the end of the branch beyond it will perifh and rot oft"; but the Mifletoe, in this cafe, is not able to fupply the place of the ftarved part of the branch, but the remainder of the' bough generally dies quite to the trunk of the tree, and the Mifletoe perifhes with it.

Though this plant is evidently propagated by its feeds, yet it alfo propagates itfelf very often by fuckers, and it is not uncom- mon to find young fhoots at a finger's breadth or two from the old one. The gardeners, who value their trees, are very care- ful to deftroy the Mifletoe from them, and that very properly, fmce it is extremely obvious from what has been obferved; that it robs the tree it grows on of a great deal of its nutritious juice. The common method of cutting off the plants to this purpofe, is, however, by no means fuftkient ; for the old ftock frequently puihes out new moots, and the roots afford fuckers, fo that the cafe becomes worfe than before. There is indeed no way of deftroying it, but the cutting away with it a part of the turbercle it forms on the branch where it grows.

The roots of Mifletoe, while young, are green, very tender, and granulated, as is alfo the bark of the older ones; but thefe have a woody filament within. They are not regularly round, but are often flat, and ufually adapted in thenfhape to the place where they are lodged ; and about their infertions it is not unfrequent to fee a fort of elongation of their bark, which blends itfelf with the bark of the tree on which they grow.

The progrefs of the branches of Mifletoe is much flower than that of the roots. The firft year, and often the fecond, is fpent wholly on their part, in the raifmg themfelves into an erect pofture, and very often this operation proves fatal to them.

The feeds, as has been before obferved, faftcn themfelves to the branches of trees, by means of the vifcous juice contained in the berries. The radicles produced hence affix themfelves by means of the hollow button at their extremity, to the baric of the tree ; and the other end being yet held fall in the feed the whole procefs forms a fort of arch. When the button end of the radicle has got itfelf good root in the bark of the tree and begins to fend up fap in abundance into its pedicle, which is to be the ftalk of the plant, that by degrees begins to loofen itfelf from the feed ; and this is often a work of great difficulty ; for the feed being firmly attached by its vifcous matter now dried to the bark of the tree, holds down the end of the ftalk, that very often the force of rifing in the young plant is not enough, and it remains in its arched form, and periihes ; and <i eftes