On Naval Timber and Arboriculture / With Critical Notes on Authors who have Recently Treated the Subject of Planting

by Patrick Matthew

It is a subject of considerable difficulty to explain the cause of slender lengthened shoots in sheltered situations, and short stout shoots in exposed. Sir Henry solves this “excellently well” in two ways, first, attributing it to shelter and exposure themselves,—“for shelter is heat, and exposure cold,”—and again, to an instinctive straining in the sheltered to reach the light, of which its neighbours deprive it every way but from above, and would do so there too if it failed to exert itself.

We find that vegetables have long spindling shoots, and wide spaces between the leaves or buds, when growing in a damp, still, close atmosphere, especially when the plant is sickly or weak from deficiency of nourishment, and that this happens equally, whether a trailing plant being supported aloft throws out depending shoots in opposition to the current of light; whether a climbing[52] plant runs out horizontally along a branch or beam at right angles to the light, or whether a self-supported mounting plant rises in direct opposition to gravity. No doubt, when the light comes from one direction, {271} such as the aperture of a window, the plant shoots forth towards the light, possibly in consequence of the leaves inclining themselves to receive the ray on their superficies, and thus leading the shoot in the direction of the light. But this does not prove any straining or lengthening of the shoot to approach the light; and we ask, what do general opinion and Sir Henry found their belief upon, of lengthening growth and straining to approach the light?

Again, with regard to heat, we notice that plants, particularly shoots from tubers, left to sprout in cold, damp, confined cellars, throw out very long stems, with wide spaces between the buds or leaves, and that very long shoots always occur in confined damp air—long in the ratio of the dampness and confinement, whatever the degree of heat may be, provided it exceed a little the vegetating point. Also on the north side of hills, the trees have generally longer stems than on the sun-ward side, although in the former case, they are exposed to the northern blast, while in the latter they bask in the sun. Has the same kind of plant, in lower latitudes, longer spaces between the leaves than in higher? And if it has not, is the cold, from greater evaporation, sufficient to balance the superior heat of the climate? {272}

The above facts must lead, we think, to the conclusion, that evaporation, or non-evaporation, of the fluids, has, directly, a very considerable influence in causing a shorter or longer extension of the shoot between the buds or leaves, and that the influence of the cold of this evaporation is at most but of a very secondary character. We would compare the extending rudiments and matter of the young scion to the slow flowing of a gelatinous fluid. In moist air, the watery part is slowly evaporated, and the drop extends into a long pendulous form. In dry air, the water of solution is quickly evaporated, longitudinal extension ceases, and the pendant is thicker and shorter. The cold of evaporation may a little affect the fluidity, but only in a very small degree[53].

The causes of the elongation of vegetables are, {273} however, not very plain. We have noticed, that the deeper the seed is placed in the ground, the braird rises the higher above ground, even when the seeds at the different depths have been equally moist. This might admit of explanation, but having already occupied too much space with this subject, we shall only remark further, that in close woods, the trees elongate, because they are precluded from extending laterally. The top buds, from receiving more of the stimulating or nourishing influence of the dew, sun’s rays, fresh unvitiated air, invigorating motion of the winds, and perhaps of electricity[54], {274} throw out a greater continuation of shoot than the under branches; nearly the whole nourishment from the soil being on this account drawn up and consumed by these top shoots, and the lower overshadowed twigs and branches languishing and dying from the absence of these advantages. Besides this extension of top shoots, by the greater continuation of leaves, or links of life, occasioned by the above causes, these shoots, owing to the moist atmosphere of the wood, also push out into longer spaces between the leaves. However, these top branches do not push sun-ward, but merely in opposition to gravity.

Sir Henry states, that “trees certainly possess some heat, otherwise they would be killed during severe frosts.” Our belief of the vital heat of vegetables is placed on a much better foundation than {275} this otherwise; otherwise our credence would be far from philosophic. Freezing cold affects many vegetables as well as some of the lower animals, only by mechanical injury, in rending the vessels by means of the expansion of the contained fluid. Now, if these vessels are not quite full of fluid, if the fluid be of such a nature as not to congeal into greater size, or if the body be small, and the vessels elastic, to yield to expansion without fracture—the vegetable or animal will often resume vitality, on being thawed from thorough congelation. We have rendered potatoes, turnips, and fruits, frost-proof, at least unless the frost was intense, by a slight desiccation caused by exposing them a short time to the air after being taken from the ground or tree[55]. In the cases where fishes and reptiles have been found {276} frozen so hard as to require a hatchet to dissect them, and reviving on thawing, it will be found that the fluids were principally oleaginous, which do not expand in congealing; and in the case of insects being frozen in masses during the night, and resuming their liveliness next day in the sun, we think, if their fluids have congealed at all, that either the vessels must have yielded, being elastic (which might more likely take place in a small body, without general fracture and derangement), or that the fluids had not extended by being congealed; but it is very probable, though frozen together in a mass of water and mud, that their fluids, from being of an acid nature, had resisted the congelation.

With regard to trees, we have heard that intense frost often splits the trunks of some of our indigenous kinds by congelation[56]; but these trees retain vitality, and only suffer from the consequences which may ensue from the fissures. We have seen evergreens, plants from milder climates, and trees which had not thoroughly ripened their {277} wood (that is, retained the vessels full of moisture), injured in the extremities, and even killed throughout by cold. But this does not prove that these had any vegetable heat, any more than those which suffered no injury from the same degree of cold, prove that they had vegetable heat. The juices of some kinds of plants do not congeal at the same point of temperature as others. The vessels of some in winter are not so much distended with fluids as others; and probably the vital principle of some is less susceptible of injury from cold than others. These facts may account for the endurance of intense cold by some kinds of trees, independent of vegetable heat.

Our author, speaking of the transplanting of fruit trees, states, that “any gardener could have predicted the probability of fruit during the first season, together with the certainty during the second of its not taking place.” Our gardeners will be moonstruck at having the gift of prophecy attributed to them, at least to predict in such a way. We have thought Sir Henry sufficiently ready to impute ignorance to gardeners before we came to this remark; but to represent a useful and intelligent class of men in so ludicrous a light, is certainly using a very improper liberty. {278}

Every gardener is aware that trees will fruit the first season after transplanting, just if they have had the rudiments of the fruit formed in the bud before transplanting, and should the blossom not be injured by severe weather. Every gardener is aware, though Sir Henry seems not, that all fruit trees, of any size, form these rudiments the season after transplanting, and that they invariably fruit the second season, if the season suit the fruiting of the kind; and every gardener of any experience is capable, even without Sir Henry’s instructions, of removing a fruit tree of considerable size, without injuring it so severely as to prevent it fruiting both first and second season, which it will do, and even mature fine fruit both years, though during the first, under very unfavourable circumstances, it should scarcely be able to develope leaves 1-5th of the usual size, and though these leaves wither and drop off long before the summer is ended, while the fruit remains to ripen on the tree. This is a direct consequence of evaporation. The thin leaves shrivel up in the ardent sun from evaporation and want of sufficient supply by root-suction; and the bulbs of the fruit, from their massiveness, contain sufficient moisture to resist withering till the night, when they drink the dews, and suck up some little moisture from the roots, undiminished {279} by evaporation in the transit, to replenish the daily loss.

Sir Henry remarks, that “no man who knows any thing of wood, will put down the oak or the elm on light sand or gravel, as it is only on deep loam and clay that the oak, in particular, will really thrive and grow into timber.” No man who knows how much a suitable soil for any kind of plant is under regulation of the moistness or dryness of the atmosphere, and other circumstances, will refrain from smiling at Sir Henry’s very superficial acquaintance with his own subject, and at the manner he thus again brings forward mankind to testify in support of his own error. Our author will place the above quotation among the errata should he take a ride up Strath-Tay from Birnam to Kenmore.