P L A 



OR, BOTANICAL DICTIONARY. 



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353 



weeds to grow on another, and the truth will be seen in the 

 different growth of the trees : in short, though the weeding 

 and cleaning is attended with an expense, the produce will 

 amply repay it, beside the pleasure that the sight of clean 

 and orderly ground affords. In the disposition of trees in 

 parks, and of shrubs and trees in gardens, there are very few 

 of those who call themselves Designers, who have had much 

 regard to this particular ; for in most of the modern plan- 

 tations, it is not uncommon to see an Oak, an Elm, or some 

 other large-growing tree, planted where a Rose-bush, a Honey- 

 suckle, or a Sweetbriar, might with more propriety occupy 

 the space; so that in a few years, if these large trees were 

 left growing, the whole plantation must make a disagreeable 

 appearance. See Nursery, and Woods. 



Plants, Diseases of. Very little being satisfactorily known, 

 till lately, upon this subject, which is of the utmost practical 

 importance to Farmers, Gardeners, Agriculturists, and every 

 lover of botanical science ; the following able little treatise, 

 recently translated from the German, of the accurate and 

 indefatigable Willdenow, is here inserted. It not only describes 

 the disease, but the cause, and the best means for restoring 

 diseased plants to health and vigour. Such directions have 

 been long wanted, and the Translator, from whose labours 

 we have extracted it, has certainly rendered a public benefit 

 to his country. " Plants," says Willdenow, " are, like all 

 other organized bodies, subject to a great many diseases. The 

 most common causes are, improper soils, preternatural habi- 

 tations, late frosts at night-time, long-continued rain, great 

 drought, violent storms, parasitic plants, insects, and wounds 

 of various kindsr Disease in plants, is that preternatural 

 state by which their functions, or at least some of them, suffer, 

 and the purpose for which they are destined prevented. The 

 diseases of plants are of different kinds ; they attack either 

 the whole plant, and are then called -general diseases; or 

 they only affect single parts, when they get the name of local 

 diseases. We style those diseases Sporadic, which, out of a 

 great number of the same species of plants, only attack one 

 or two, as consumption ; Epidemic, on the contrary, when 

 they attack a great number of plants, such as gangrene, 

 necrosis, rubigo, and others. The diseases of plants are 

 either such as attack them externally, and are occasioned by 

 various causes, or they proceed from internal sources. The 

 former are, upon the whole, much more easily healed than the 

 latter. The diseases which proceed from internal causes, 

 originate in the increased or diminished irritability of the 

 fibre, and this may be also produced by a variety of causes. 

 The cure of plants is very simple: either the injured part is 

 cutoff, or the soil, the situation, and the degree of temperature, 

 altered. To these expedients only, the healing of all plants 

 is restricted. In vegetables, as well as in animals, diseases 

 occur which are incurable, as consumption, canker when it is 

 concealed, mutilation, deformity, &c. Most of them, how- 

 :ver, may be remedied. Vulnus, or a wound, is the separation 

 of the solid parts by external violence. It may be occasioned 

 purposely by cutting off branches, or accidental rubbing off; 

 by friction of cattle ; or by friction against another object, 

 when the wind agitates the stem; by the bite of animals; by 

 the falling off of the parasitic plants; or even by very large 

 hailstones. In all these cases, it is necessary to prevent the 

 access of air to it, by some good firm cement, or grafting wax. 

 But if the wound has remained long uncovered, and exposed 

 both to wind and rain, and is of a great size, then the affected 

 part must be cut off down to the sound wood, to prevent 



Kjreater mischief, and the whole afterwards be covered with 

 ^ax. The means of preventing wounds are obvious. Branches 

 nust be cut off cautiously; the access of cattle must be ob- 



structed; trees brought up, so as not to be fastened to stakes; 

 or, if it cannot be avoided, to place three or four posts or 

 stakes round each, and tie them up very gently. In violent 

 storms, it is indeed better to let them loose, and leave them 

 to themselves. Parasitic plants must be eradicated. Against 

 the bite of smaller animals, and hail, precautions cannot 

 always be taken. Fractura. Fracture is the separation of 

 the stem and branches into many pieces. "This may arise 

 from the violence of the wind, from too great an abundance 

 of fruit, much snow, or even from lightning. It is remark- 

 able, that lightning runs along every species of trees, almost 

 always in a different manner. The birch (Betula alba) is, in 

 this respect, different from all other trees, that the lightning 

 never runs along its stem, but only at the top beats off the 

 boughs almost in a circular direction. A fracture, if not 

 complicated, and on branches or young stems only, may bu 

 healed without difficulty. But when accompanied with con- 

 tusion, or happening in trunks of old or gummy trees, no way 

 of recovery is known. In young trees and branches, even 

 sometimes in old ones, when instantly discovered, fractures 

 heal easily, especially in spring till the end of June, provided 

 every part be brought into its natural position, firmly tied up, 

 and properly supported. But if there is contusion, or if a 

 thick stem or bough is affected, the bough must be cut off, 

 or the stem cut down, to get new shoots from the stock or 

 from the root. To prevent such an accident, trees with fra- 

 gile boughs must be, as much as possible, sheltered from the 

 wind. Fruit-trees should not, when pruned, have all their 

 gems left ; and care should be taken in gardens, that the 

 snow do not overload the boughs. Against the flash of 

 lightning, no means are of any service, except bringing con- 

 ductors, a plan which would be too expensive, and even 

 impracticable. Fissura. Fissure is the separation of the 

 solid parts into an oblong cleft, which ensues spontaneously. 

 It proceeds from two causes ; fulness of juice, or from frost. 

 To heal a split, nothing else is required than to put good 

 grafting wax on the wound, that the rain or other contents 

 of the atmosphere may not destroy the stem. To prevent 

 clefts, the bleeding or scarifying, as it is called, of such trees, 

 the bark of which is very hard, may be of service. A mode- 

 rate incision is made through the bark longitudinally; and a 

 plant that has too rich a soil, by which it becomes too succu- 

 lent, should be transplanted into a poorer soil. To defend 

 them against frost, plants should be covered with straw. A 

 cleft occasioned by frost, sometimes degenerates into a chil- 

 blain, from which afterwards, especially in Oaks, a blackish 

 sharp liquor exudes, which at last produces exulceration. 

 Defoliatio notha, is when the leaves fall not at the proper 

 period, but much earlier. It is occasioned by men, insects, 

 acrid fumes, dust, and constant dry weather. In whatever 

 way it may happen, all depends on the nature of the plant 

 affected with it, and on the season of the year in which- it 

 happens. If it be a fast-growing tree, and the injury happens 

 before August, the tree may, if taken good care of, easily get 

 leaves again, only it will have smaller foliage for the present 

 season. But if the leaves fall after that period, and cool 

 weather comes on earlier than usual, or if it happens at a 

 much later season, the plant maybe unwell for several years 

 before a complete recovery takes place. If, on the contrary, 

 it happens late in autumn, just before the natural fall of the 

 leaves, then it has no bad consequences; except the plants 

 be natives of a warmer climate, and the branches which have 

 appeared already, be not yet hard enough, in which case they 

 will lose those branches, and perhaps some of the older ones, 

 by the invasion of cold. The defoliation by men, which is 

 performed sometimes in spring, particularly with the Mulberry- 



