302 



PHY 



THE UNIVERSAL HERBAL; 



PHY 



annually renewed, and the old ones die. On this account 

 we find in most of them, for few live more than one year, 

 only one circle. Bulbs, have at their base a fleshy bottom, 

 from which radicles and new bulbs shoot forth. This con- 

 sists of a reticular plexus of vessels, which are not circular as 

 in other roots. These plants change their station, and, in 

 common with animals, move from one place to another. 

 The creeping root runs forth under ground; the branch, 

 from which the new shoot arose, dies; and the young loot 

 .now becomes attached to a distant spot. The palmated 

 and testiculated roots, consist of two knobs, one of which 

 completely dries up, and on the opposite side a new one 

 is formed. This happens every year; and the plant in this 

 way, after many years, appears on a different spot. .. Solid 

 bulbs, especially the bulb of the Colchicum autumnale, 

 undergo the same change; on the side of the old bulb a 

 new one appears, the old one decays, and the whole at last 

 becomes attached to neither place: and this is the case 

 with most bulbs and tuberous roots. Very re'markable, 

 and deserving particular attention, is the choice of food, 

 which has been observed in some of the creeping roots. A 

 Strawberry plant, in a garden of excellent soil, was planted 

 in a particular spot filled with sterile sand. Stalks and roots 

 all grew out towards the sides where the good soil was, but 

 the main plant decayed. Several other remarkable instances 

 are, at present, inexplicable; so little do we know of the 

 physiology of plants. 



" The descending stem, is probably composed of the stalk 

 of the root, radicles, knobs or bulbs of various form, and 

 these parts are almost always covered with fibres, which, like 

 leaves, are renewed every year. In spring and autumn, and 

 even in winter, when every thing is covered with snow, new 

 ones, in cold and temperate climates, spring in place of the 

 old dry ones. In warm and hot climates this happens during 

 the rainy season, therefore always at a period when the vege- 

 table world appears to sleep. The radicles grow in the fol- 

 lowing manner; a small bundle of air vessels lengthens, 

 pierces the cutis, and runs into the ground. It is inclosed 

 in a delicate cellular texture, covered by a thin membrane. 

 Thus^the extreme point of such a radicle is merely the end 

 of the spiral vessels, which absorbs the necessary food from 

 the soil. Those fibres, which are never wanting in earthly 

 plants, cannot perform this function of taking up food longer 

 than one summer, after which they must be succeeded by new 

 ones. All plants do not grow in earth, and therefore the 

 roots of some do not enter the ground. The parasitic plants 

 are of this kind. The Cuscuta Europaa, when it germinates, 

 lengthens its filiform plumule, winds round neighbouring 

 growing plants, as Flax, Nettles, &c. andr'unsalongthem. Its 

 restel decays, and along the whole surface of the filiform 

 branching stalk, a kind of warts shoot out, where it rests upon 

 the other plants, serving as roots. Algee, but especially 

 Lichens, are, by similar warts, attached to the trunk of trees, 

 and few pierce their external membrane. The Sphseriae grow 

 mostly on the inner bark of old decayed trees ; they pierce 

 or elevate the external membrane, and are firmly attached by 

 wart-like roots. The Misletoe (Viscum album) pervades 

 with its roots the woody part of branches, and becomes inti- 

 mately blended with it. Amongst the numerous species of 

 parasitic plants which the torrid zone produces, one species 

 is particularly distinguished, which grows abundantly in the 

 Indies beyond the Ganges, the Epidendrum^os aeris, for it 

 grows and blossoms in the air, when hung up in a room. 

 Mr. Loureiro, who saw this himself, assures us, that it vege- 

 tates hung from the ceilings of rooms for years, and is remark- 

 ably reviving to the inhabitants by the fine odour of its 



blossoms. Lantaria Chinensis and Rhapis amndinacea, as 

 well as some other small Palms, are remarkable from having 

 a part of their root next the stump springing from the earth, 

 whence they have the appearance of being attached to a 

 withered stump. The root is indeed, in the strictest signi- 

 fication, the plant itself. The stalks, leaves, and flowers, 

 issuing from it, are only its elongations, which it makes on 

 purpose to get proper nourishment. These may be cut off, 

 and the root will always again throw out new elongations. 

 The root may be divided, and each part will form a plant by 

 itself; not so the stem, except in some ligneous plants, where 

 the stem is merely the root elongated. Resinous or dry plants, 

 as Pinus, Erica, Rhododendrum, are an exception to this, as 

 in them the stem can rarely be injured, without injuring the 

 whole plant. Many experiments made by inverting plants, 

 prove clearly that the descending stem is not different from 

 the stalk above ground. If a Plum or Cherry tree, not too 

 thick, be bent with its top towards the ground in the autum- 

 nal season, one half of the top buried in the ground, and one 

 half of the roots carefully taken out of the earth, covered at 

 first with moss, and then gradually left quite uncovered; if 

 afterwards, in the following year, the same is done with the 

 rest of the top of the tree and the roots, the tree will shoot 

 forth leaves, on the branches of the root, and roots from those 

 of its top, and in due time the root will come to blossom and 

 bear fruit. A Willow is best adapted for making this experi- 

 ment in a short time, and with success. 



" We have seen, that the root arises from the rostel of the 

 seed; and from the plumule, which is always bending upper- 

 most, the upper part of the plant above ground, whatever its 

 shape may be. The stem of herbs and shrubs, as well as the 

 trunk, the scape, and the stalk, in short, all the varieties of 

 the stem, have a channel full of pith, surrounded with a ring 

 of adducent and air vessels. In the cellular texture lie the 

 reducent vessels. The cellular texture, and membrane full of 

 lymphatics, inclose the whole. The ring which the larger 

 vessels form, accords with the form of the plant; triangular, 

 pentagonal, or hexagonal. The same happens in the growth 

 of the stems of trees and shrubs during the first year. Every 

 year a new bundle of adducent and air vessels in a circular 

 form is added externally to the old ones. The innermost 

 bundles of vessels are more and more compressed, till the 

 pith at last, except where this is natural to some shrubs and 

 trees, entirely disappears, or is compressed to a very small 

 point. The interior vascular circles become annually more 

 dense, and at last get so hard as to form what is called wood. 

 The less, or half-indurated external circles, consitute the 

 alburnum; and the outermost one, which is just newly formed, 

 is now called the inner bark. This last, then, is a circle 

 round the stem of the tree, consisting of numerous, young, 

 new-formed vascular bundles. It is divided into two parts, 

 the exterior layer changing into bark, the interior first form- 

 ing the alburnum, and then the wood. The bark, in ligneous 

 plants as well as in herbs, is green and vascular; but as soon 

 as it grows older, its green colour changes into brown; still 

 the lymphatics retain their power. But the more the tree 

 advances in age, the browner and darker the bark grows; it 

 cracks, and the function of expiration cannot go on as before, 

 nor are the vessels in the cuticle any longer visible. Some 

 trees and shrubs lose their bark annually, and reproduce" a 

 new one from the inner bark. As instances, may be given 

 the Platanus occidentalis, and the Potentilla/rac^'eosa. The 

 age of a tree or shrub may be easily determined by the number 

 of these ligneous circles, upon cutting the stem off, close to 

 the root. In the same manner the main root shews most 

 accurately the age by its ligneous circles, when cut directly 





