Leaf scar

“ Leaf-scars transversely rhombic or oval with three vascular scars, the central largest. Leaves very long and one-nerved. Large strobiles or branchlets borne in two ranks or spirally on the sides of the stem, and leaving large, round scars (cone-scars) , often with radiating impressions of the basal row of scales.
Species with long or drooping leaf-bases have been included in Lepidophloios and Lomatophloios, Species with short leaf-bases and cone-scars in two rows have been called Ulodendron, and some of them have been included in Sigillaria (sub-genus Clathraria) . ”

“ Trees, with smooth gray bark becoming on old trunks rough or scaly, strong hard tough brown heartwood, pale sapwood and tough terete flexible branchlets, solid pith, buds covered with few valvate or with numerous imbricated scales, the axillary buds much smaller than the terminal. Leaves often glandular-dotted, their petioles sometimes persistent on the branches during the winter, and in falling leaving large elevated oblong or semiorbicular more or less 3-lobed emarginate leaf-scars displaying small marginal clusters and central radiating lines of dark fibro-vascular bundle-scars ”

“ Before considering the nature and origin of the scars it is important to remember the considerable size to which they may attain; other points of importance are the occurrence, either in the centre of each depression or in an excentric position, of an umbilicus or slightly projecting boss, in the centre of which is a pit formed by the decay of an outgoing vascular strand. The sloping sides of the scars sometimes bear elevations resembling leaf-cushions like those on the rest of the stem surface. In the specimen shown in fig. ”

“ Like whispering voices, the trembling leaves sing rejoicingly in the breeze and summer sunshine, and they tremble alike with agony when the equinoctial gale rends them from the parent stalk. The influences which pervade the whole, making up the sum of vital force, are disturbed by every movement throughout the system; a wound on a leaf is known to disturb the whole, and an injury inflicted on the trunk interferes with the processes which are the functions of every individual leaf. ”

“ Bark-boring—Wood-boring—Wood fungi—Leaf-miners—Pith flecks—Erosions. Skeleton leaves—Irregular erosions—Shot holes. Frost cracks—Strangulations—Spiral grooving.
Natural wounds are produced in a variety of ways during the life of the plant, and, generally speaking, are easily healed over by the normal process if the area destroyed is not too large, and the parts remaining uninjured are sufficiently provided with foliage, or with supplies of food-materials stored up in the roots, rhizomes, medullary rays, etc., to feed a vigorous callus. ”

“ If a crooked sprout is not made straight before it gets to be a young tree, it can never entirely outgrow the defect. If it received a wound before it grew to be a young tree, nature may heal the wound but the scar will indicate a weak place when it is grown. ”

“ A rain discharges them in astonishing numbers. Rising in the air (for they are incredibly light) , these spores lodge on the unfolding leaves and flowers of the apple, and there begin to germinate, invading the tissue. The tissue is penetrated and killed so rapidly that the practiced eye soon discovers a "spot." The leaf, if badly infected, may not reach full size; it may curl; it may die and fall; the tree thereby is injured. ”

“ Wherever the bark is dead and dry, the limb will flourish above it, make new wood, ripen its fruit, but perish the ensuing winter. In the other case, as soon as the circulation of the sap becomes active, the point described shows signs of disease, the leaf turns to a darker brown than is natural to its ordinary decay, being nearly black, and the wood perishes. ”

“ The breaking of a branch, or the removal of a portion of the bark, may inflict a serious injury, but it is one which, under ordinary circumstances, will be recovered from, without any impairment of the health of the tree—unless where the wound is so large that the new growth will not soon cover it over, in which case exposure to the moisture [186] of the atmosphere may result in decay of the woody tissues, or, if the sap exudes, at certain seasons, it may produce canker and fungous growths. ”

“ The phenomena described occur in all cases of cicatrization of wounds in nature—e.g. leaf tissue, young stems, roots, &c., when cut or pierced by insects, thorns and so forth They are concerned in the occlusion of broken twigs and of falling leaves, and it is from the actively growing “callus” developed at the surface of the wounded tissues of cuttings, buddings, prunings, &c., that the healing and renewal of tissues occur of which advantage is taken in the practice of what might well be termed plant surgery. ”

“ Sun-cracks are due to intense insolation on the south side of trees in clear weather in early spring, causing the drying and contraction of the wood and its coverings down that side of the tree: the contracted tissues consequently split, as in the case of frost-cracks, the healing up of which is very similar.
Dying-back.—All that is true of the necrosis of cortical tissues in small patches also applies to cases where the whole of the outer tissues of thin twigs and branches die of inanition owing to a premature fall of leaves—e.g. after a severe attack of some insect or fungus pest. ”

“ The name describes the disease at maturity so that all may know it. Black, canker-like lesions spot the fruit, leaf, and twig. These are most characteristic on the pear. The scabs first appear on the fruit as olive-green velvety spots; the young fruits may drop; if they persist, growth may cease, the skin crack, or the fruit be distorted; the fruit-stalk is often shriveled. The scab shows on the leaves much as on the fruit and usually attacks the lower surface. ”

“ If instead of a simple tissue, the cut or other wound lays bare a complex mass such as wood, the resultant changes are essentially the same to start with. The living cells bordering the wound form cork, and then those deeper down grow out and form a callus. The exposure of the wood however, entails alterations in its non-living elements also. ”

“ Loose bark, put back against a tree, will never grow and will only tend to harbor insects and disease. Bandages, too, are hurtful because, underneath the bandage, disease will develop more rapidly than where the wound is exposed to the sun and wind. The application of tin or manure to wounds is often indulged in and is equally injurious to the tree. The secret of all wound treatment is to keep the wound smooth, clean to the live tissue, and well covered with coal tar. ”

“ Excited by the struggles of the victim, the sensitive hairs close only the faster, working on the same principle that a vine's tendrils do when they come in contact with a trellis. More of the sticky fluid pours upon the hapless fly, plastering over his legs and wings and the pores on his body through which he draws his breath. Slowly, surely, the leaf rolls inward, making a temporary stomach; the cruel hairs bind, the glue suffocates and holds him fast. Death alone releases him. ”

“ The mother, therefore, having made her selection, takes up her stand on the stalk of the leaf and there patiently drives in her rostrum, turning it with a persistency that denotes the great importance of this thrust of the bodkin. A little wound opens, a fairly deep wound, which soon becomes a point of mortification. ”

“ The simplest is that of a longitudinal, oblique, or horizontal short cut in which the point of the knife severs all the tissues of the stem down to the wood. The first effect usually observed is that the wound gapes, especially if longitudinal, because the cortex, tightly stretched on the wood cylinder, contracts elastically. This exposes the living cortex, phloem and cambium to the air, and such tissues at once behave as already described above: the cells actually cut die, [196] those next below grow out under the released pressure, and these give rise to cells which become cork. ”

“ Trees, or rarely shrubs, with deeply furrowed bark, branchlets often furnished with corky wings, and buds with numerous ovate rounded chestnut-brown scales closely imbricated in two ranks, increasing in size from without inward, the inner accrescent, replacing the stipules of the first leaves, deciduous, marking the base of the branchlet with persistent ring-like scars. Leaves simply or doubly serrate; stipules linear, lanceolate to obovate, entire, free or connate at base, scarious, inclosing the leaf in the bud, caducous. ”

“ The cooling properties of leaves would be recognised by the most primitive peoples; and as a cut or other wound, by the process of inflammation, at once begins to burn and throb, a cooling leaf would be the most natural thing to apply. Some leaves which possess styptic and resinous properties would staunch bleeding very effectually, and the mere act of binding round the cut an application like a leaf would serve to draw together the edges of the wound, and afford an antiseptic plaster of the most scientific nature. ”

“ If we look at a ripe bean or pea or any seed we shall find upon one edge of it the scar where the little stem was attached. The scar is the umbilicus or "navel" of the seed. The seed does not become free from its attachment to the pod until it is able to live alone. As long as it continues to grow it remains attached and receives the sap. As soon as it has its growth and no longer needs the sap it separates from the pod. This separation is easy and natural. There is no tearing apart, no mutilation. It is exactly like the falling of the leaves in [Pg 68] the Autumn. ”

“ The only remedy is to cut and burn the trees and replant, in the same places if desired, as, the disease does not seem to be carried by the soil.
PEAR ENEMIES Pears are sometimes affected with a scab similar to the apple-scab, and this is combated by the same treatment—three sprayings with Bordeaux.
A blight which causes the leaves suddenly to turn black and die and also kills some small branches and produces sores or wounds on large branches and trunk, offers another difficulty. Cut out and burn all affected branches and scrape out all sores. ”

“ A layer of cork is regularly formed in most Phanerogams across the base of the petiole before leaf fall, so as to cover the wound caused by the separation of the leaf from the stem. Special “wound-cork” is also often formed round accidental injuries so as to prevent the rotting of the tissues by the soaking in of rain and the entrance of fungal spores and bacteria. A peculiar modification of periderm is rormed by the phellogen in the submerged organs (roots or stems) of many aquatic or marsh-loving plants. ”

“ Plants have their troubles as well. Perhaps you have noticed on wild cherry trees growing by the roadside, or on plumb trees, that sometimes almost every tree in a clump, and even every branch on a tree, will have a hard black lump, as large as your fist, growing out of the bark. The tree is sick; sick with a patching disease of trees called the black knot.
The disease itself is something like a mold. It breaks through at the growing tip of the branch where the bark is new and thin. Thence it grows down the branch sucking up the living substance of the plant and killing everything as it goes. ”

“ If the scar is small the woody growth quickly comes in from each side and covers it. If the scar is very large, occupying perhaps one-quarter or one-third of the circumference, the tree is likely never to recover and the burnt place remains permanently on its side. ”

“ Leaf diseases, by killing a greater part of the foliage, destroy the very organs in which food for the growing tissues is prepared. [160] Diseases of the bark intercept the flow of food coming down in the bark from the leaves. Diseases of the sapwood cut off the water supply, which is pumped upward from the roots. Those that attack the roots also affect the water supply of the tree. ”

“ If they have farther progressed in their destructive work, the leaves will prematurely decay. On this appearance, turn up the leaf, and you will see them running about with incredible swiftness. Their body is of a blood colour, and their feet, eight in number, light red. When very numerous, they work thick webs on the under side of the leaf, and frequently all over it, forming a mass of half dead plants, decayed leaves, and thousands of spiders. The most effectual remedy is a thorough syringing with water, and profusely under the foliage. ”

“ Owing to the natural exfoliation of the superficial layers of the outer bark at a certain stage in the growth of the plant, or in some instances no doubt as the result of post-mortem decay, which destroys the delicate cells of the meristematic zone in the outer cortex, isolated leaf-cushions and strips of the external surface are occasionally met with as carbonised impressions. ”

“ We have all heard of driving rusty nails into trees (thinking the iron produced the beneficial results) , cutting a slit in the bark of the limbs and trunk for "bark bound" so called, etc., all of which have stimulating effects with more or less permanent injury to the tree. Who knows but what the sap sucker, with his ability to dig into the bark and extract a piece of cambium, was not sent to us to aid in preserving our trees by stimulating new growth?
In my work last summer trees that were subjected to slight injury before hand apparently accepted a larger proportion of grafts. ”