Mesophyll

“ In longitudinal sections, the cells, except of the mesophyll (green tissue) are much elongated. The mesophyll cells, however, are short and the intercellular spaces much more evident than in the cross-section. The colorless cells have frequently rounded depressions or pits upon their walls, and in the fibro-vascular bundle the difference between the two portions becomes more obvious. The wood is distinguished by the presence of vessels with close, spiral or ring-shaped thickenings, while in the phloem are found sieve tubes, not unlike those in the ferns. ”

“ The leaves of shade plants have little or no differentiation of palisade tissue. In fleshy leaves which contain a great bulk of tissue in relation to their chlorophyll content, the central mesophyll contains little or no chlorophyll and acts as water-storage tissue. The cortex of a young stem is usually green, and plays a more or less important part in the assimilative function. ”

“ Mesophyll. bodies of the higher plants its functions are numerous. In all green plants which have a special protective epidermis, the cortex of the shoot has to perform the primitive fundamental function of carbon assimilation. ”

“ I am afraid it has been rather a difficult history to follow step by step, and yet it is perfectly clear when once we master the succession of growths. Starting from a spore, the thread-mass or protonema gives rise to the moss-stems forming the dense green carpet, then the green flowers on some of the leaf-stems give rise to a plant-egg, which roots itself in the stem, and grows into a perfect plant without leaves, bearing merely the urn in which fresh spores are formed, and so the round goes on from year to year. ”

“ These abound in the cells of all common leaves and the green rind of plants, wherever exposed to the light. The green color is seen through the transparent skin of the leaf and the walls of the containing cells. Chlorophyll is essential to ordinary assimilation in plants: by its means, under the influence of sunlight, the plant converts crude sap into vegetable matter.
418. Far the largest part of all vegetable matter produced is that which goes to build up the plant's fabric or cellular structure, either directly or indirectly. ”

“ Thus we see that the flowering plant is essentially the equivalent of the asexual fern, and of the sporogonium of the moss, and the pollen cell and the embryo-sac represent the two spores of the higher cryptogams, and the pollen tube and the germinal vesicles and antipodal cells are all that remain of the sexual generation, seen in the moss as a leafy plant, and in the fern as a prothallium. ”

“ In the modern world we divide all vegetation into two great series, that of the Flowering Plants (Phænogams) , which also produce true fruits and seeds, and that of the Flowerless Plants (Cryptogams) , which produce minute spores instead of seeds. The latter is in every respect the lower group. This lower series is again divisible into three classes—first and lowest, that of the Seaweeds, Moulds, and Lichens (Thallophytes) . Secondly, that of the Mosses and their allies (Anophytes) . Thirdly, that of the Ferns, Equisetums and Club-mosses (Acrogens) . ”

“ Intense xerophytes and hydrophytes are much more fixed than mesophytes, though the intensity of the stimulus has doubtless as great an influence as its duration. Composites, labiates, grasses, orchids, etc., are less plastic than ranals, rosals, etc., but there are many exceptions to the apparent rule that fixity increases with taxonomic complexity. ”

“ Mesophytes.—Warming defines mesophytes as “plants that show a preference for soil and air of moderate humidity, and avoid soil with standing water or containing a great abundance of salts” (1909: 317) . Under mesophytes, Warming places plants occurring in “Arctic and Alpine mat-grassland and mat-herbage,” in “mat-vegetation of the Alps,” in meadows, in pasture on cultivated soil, in “mesophytic bushland,” in deciduous dicotyledonous forests, and in evergreen dicotyledonous forests. ”

“ A system of phytons constitutes the higher plants. In the history of plant life the morphology of plant phytons is an important part of the science of botany, for the forms of phytons undergo a succession of changes, the investigation of which vies in importance with that of the chemical development of kinds to which we have heretofore alluded. ”

“ But the blindness of those who think it absurd to suppose that complex organic forms may have arisen by successive modifications out of simple ones, becomes astonishing when we remember that complex organic forms are daily being thus produced. A tree differs from a seed immeasurably in every respect—in bulk, in structure, in colour, in form, in chemical composition: differs so greatly that no visible resemblance of any kind can be pointed out between them. Yet is the one changed in the course of a few years into the other: ”

“ Sometimes, as in the case of peach and plum trees, which are often dwarfed, the plants are thrown into a flowering state, and then, [Pg 98] as they flower freely year after year, they have little inclination to make vigorous growth. ”

“ Soon—it is merely a question of days—the swelling buds displace millions of leaf-sheaves, pale green and fragile, which fall and, curling in on themselves, redden, and again the yellow sand is littered, while overhead fresh foliage, changing rapidly from golden, glistening brown to rich dark green, makes one compact blotch. And when the wind torments sea and forest, and branches bend and sway, and creepers drift before it, the white blooms of the orchids, so light and delicate that a sigh agitates them, might be “foam flakes torn from the fringe of spray” and tossed aloft. ”

“ The trees bathed their great heads in the waves of the morning, while their roots were planted deep in gloom; save where on the borders the sunshine broke against their stems, or swept in long streams through their avenues, washing with brighter hue all the leaves over which it flowed; revealing the rich brown of the decayed leaves and fallen pine-cones, and the delicate greens of the long grasses and tiny forests of moss that covered the channel over which it passed in motionless rivers of light. ”

“ Deep in perpetual shadow lived a shy plant with heart-shaped leaves, so succulent and distended as to resemble green capsules, and in association with each leaf was a single semi-transparent fruit, pink with a central glow like the fire of opal, but so frail that upon touch it resolved into a dewdrop which glistened, trembled, and was gone in a moment. ”

“ All the books and instructions insist that the selection of the soil is the most important part of gardening. No doubt it is. But, if a man has already selected his own backyard before he opens the book, what remedy is there? All the books lay stress on the need of “a deep, friable loam full of nitrogen.” This I have never seen. My own plot of land I found on examination to contain nothing but earth. I could see no trace of nitrogen. I do not deny the existence of loam. There may be such a thing. But I am admitting now in all humility of mind that I don’t know what loam is. ”

“ The shadows of leaves fall upon their arms, as they spread the branches apart, but their shoulders are in the sun. The skin of their arms is like a blue mist, but their shoulders are white and glowing, as if the light fell not from above, but rose from under their skin. We watch the leaf which has fallen upon their shoulder, and it lies at the curve of their neck, and a drop of dew glistens upon it like a jewel. ”

“ That they may bind the moss in leafy nets. ”

“ I suppose in reality not a leaf goes yellow in autumn without ceasing to care about its sap and making the parent tree very uncomfortable by long growling and grumbling—but surely nature might find some less irritating way of carrying on business if she would give her mind to it. Why should the generations overlap one another at all? ”

“ The ash her purple drops forgivingly
And sadly, breaking not the general hush;
The maple-swamps glow like a sunset sea,
Each leaf a ripple with its separate flush;
75All round the wood's edge creeps the skirting blaze
Of bushes low, as when, on cloudy days,
Ere the rain falls, the cautious farmer burns his brush. ”

“ Said Pretzel, 'and the gods are growing old;
The stars are singing Golden hair to gray,
Green leaf to yellow leaf—or chlorophyl
To xanthophyl, to be more scientific,—
So speed me one more stein. ”

“ All is lovable—from crescentric sandpit—coaxing and consenting to the virile moods of the sea, harmonious with wind-shaken casuarinas, tinkling with the cries of excitable tern—to the stolid grey walls and blocks of granite which have for unrecorded centuries shouldered off the white surges of the Pacific. The flounces of mangroves, the sparse, grassy epaulettes on the shoulders of the hills the fragrant forest, the dim jungle, the piled up rocks, the caves where the rare swiftlet hatches out her young in gloom and silence in nests of gluten and moss—all are mine to gloat over. ”

“ For some, the lofty banquet-hall, splendid with reflected lights and the flash of crystal and silver and the triumphal strains of a full band hidden by a screen of palms and tree-ferns. There are others best to be eaten to slow, soft music in a flower-bedizened glade of fairy-land.
September is the season of scents. Partly as a result of the dryness of the month, the mango trees continue to bloom as though each had determined (for the time being) to abandon all notion of utility and to devote itself solely to the keeping up of appearances. ”

“ What the mulberry leaf is to the silk-worm, the author's book, treatise, essay, poem, is to the critical larva; that feed upon it. It furnishes them with food and clothing. ”

“ Nature will bear the closest inspection. She invites us to lay our eye level with her smallest leaf, and take an insect view of its plain. ”

“ You will, I trust, resemble a forest plant, which has indeed, by some accident, been brought up in the greenhouse, and thus rendered delicate and effeminate, but which regains its native firmness and tenacity when exposed for a season to the winter air. ”

“ Though I do not believe that a plant will spring up where no seed has been, I have great faith in a seed—a, to me, equally mysterious origin for it. Convince me that you have a seed there, and I am prepared to expect wonders. ”

“ How can I think of myself when infinitude o'er me is glowing,
Glowing with tokens of love from the land where my sorrows shall cease?
Oh, summer-night of the South! Oh, sweet languor of zephyrs love-sighing!
Oh, mighty circuit of shadowy solitude, holy and still!
Music scarce audible, echo-less harmony joyously dying,
Dying in faint suspirations o'er meadow, and forest, and hill!
I must go forth and be part of it, part of the night and its gladness.
But a few steps, and I pause on the marge of the shining lagoon. ”

“ For several weeks the starlings train themselves for the long Northern flight and its perils, dashing with impetuous speed through the forest and wheeling up into the sky until they disappear, to become visible again as black dots hurtling through space when the sunlight plays on their glossy feathers as the course of the flock is changed. With the rush of a wind of small measure but immense velocity, the flock descends earthwards, among and over the trees, perfecting itself by trials of endurance and intricate alertness. ”

“ The bud disappears when the blossom breaks through, and we might say that the former is refuted by the latter; in the same way when the fruit comes, the blossom may be explained to be a false form of the plant's existence, for the fruit appears as its true nature in place of the blossom. These stages are not merely differentiated; they supplant one another as being incompatible with one another. ”

“ Many trees endure sadly the decoration of orchids in full flower, some lovely to look on and deliciously scented. The snowy plumes of one species sway gently, as if offering friendly greeting. A worthy similitude to the lily of the valley clings to a decaying limb, and a passing smudge of lustrous brown is but the reflection from a mass of the commonest of the Dendrobiums which encumbers a long-suffering host. Where forest trees and wattles guard the bank the water is of a different hue, as if the face of the river had absorbed less of the actualities of the sun. ”

“ Nature has no consolation for us. Out of her formlessness issue forms which return to formlessness,—that is all. The plant becomes clay; the clay becomes a plant. When the plant turns to clay, what becomes of the vibration which was its life? Does it go on existing viewlessly, like the forces that shape spectres of frondage in the frost upon a window-pane? ”

“ Look at a plant in the midst of its range! Why does it not double or quadruple its numbers? We know that it can perfectly well withstand a little more heat or cold, dampness or dryness, for elsewhere it ranges into slightly hotter or colder, damper or drier districts. In this case we can clearly see that if we wish in imagination to give the plant the power of increasing in numbers, we should have to give it some advantage over its competitors, or over the animals which prey on it. ”

“ It was all down, down, down, gradually—ruin and levelling and disappearance. Then it was all up, up, up, gradually, as seeds grew to saplings, and saplings to forest trees, and bramble and fern came creeping in to help. ”

“ In the span of my own lifetime I have observed such wondrous progress in plant evolution that I look forward optimistically to a healthy, happy world as soon as its children are taught the principles of simple and rational living. ”