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Some Successful Plants

BY A. J. GROUT, Ph.D.

Na lawn or a garden there is constant annoyance because of weeds, that will grow in spite of all our efforts to the contrary, while the plants that are desired often refuse to thrive even though cared for with the greatest solicitude. Again, some plants appear to thrive in situations so unfavorable that one would say it were impossible but for the self-evident facts. In the chinks between the flagstones of our busy city streets, in well-worn paths, in heaps of coal ashes and cinders, are found many humble but eminently successful plants. Success in plant life does not mean a great show of beautiful flowers or foliage or a high and exalted worldly position. It means the ability to obtain sufficient nutrition so that the plant may make a vigorous growth and produce flowers which shall be fertilized and produce a large number of sound, viable seeds,-i. e., seeds which will grow. For each seed contains a baby plant carefully wrapped from cold and wet, and upon the number and vigor of these seeds depends the next generation of plant life.

DANDELION

Section of fruithead closed

Additional elements of success are habits and devices which protect the plant from its various enemies, and various devices for scattering the seeds far and wide.

Measured by these standards our commonest weeds are the plants most successful in the struggle for existence, which is constantly going on in the case of every living thing, from microbes to man. A careful study of a few of the familiar despised plants to discover the secrets of their success is most fascinating; for the objects of study are open to all, even in the most crowded city,

and to learn wonderful things of common and despised objects arouses enthusiasm in the most listless. Moreover, only a small portion of these secrets has ever been extracted from our humble acquaintances, and the study has all the charm of original investigation.

Perhaps none of our plants is more common or more familiar than the Dandelion, and certainly none is more wonderful. First of all, it is not a native, but was introduced from Europe, whence have come many of our worst weeds, fitted by centuries of struggle in cultivated fields to overcome the native plants of a continent where cultivation had previously been practically unknown, and where natives had had no opportunity of adapting themselves to the conditions of civilized agriculture.

One of the Dandelion's strongest points is the ability to obtain nourishment under strong competition and in unfavorable situations. A deep, strong, perennial tap-root draws all available nourishment and moisture from surface and subsoil, stores nourishment during the winter, and enables the plant to start far and away ahead of most of its competitors. The Dandelion blossom is one

DANDELION Section of fruit-head open

of the very first to appear in the fields and parks of New York city. This same tap-root is exceedingly bitter, which very likely protects it from destruction by moles and other animals. At least I do not remember having seen a root that had been disturbed by animals of any kind. But only a small portion of its food comes from the soil. Air and sunshine are just as necessary, for the air is food and the sunshine is digestion for our vegetable neighbors. Note the shape of the leaves; narrow at base and widening to the outer end, they form a dense rosette that not only gets for the Dandelion all the air and sunshine coming its way, but smothers all but the most sturdy competitors. Here lies the secret of the Dandelion's presence in lawns and walks and open waste places. In lawns the grass is kept low, so that it cannot overtop and shade the Dandelion, while its own leaves lie so low and close that they are little hurt by the mower and can smother the grass underneath. Let the grass grow, and the Dandelion must raise and lengthen its leaves and stretch them up toward the sunlight. For a while it will do this, but the contest soon proves too much for even a Dandelion, and you will seldom find Dandelions in heavy grass-lands or land growing tall plants, except on the edges next open spaces.

The large, strong root and the widespreading leaves furnish nourishment sufficient to produce abundant flowers and seeds, but mere nourishment is not enough. Seeds with their delicately cradled infants cannot be produced unless the tiny pollen dust is carried from one flower to another. As the Dandelion cannot walk, she must hire messengers, and the brilliant golden glory of the flowers is not primarily designed for our enjoyment, but as a flaming advertisement of "Nectar Within." And nectar there is indeed, and so abundant and easy of access that almost any insect can obtain it. Müller noted ninety-three species of insects visiting the Dandelion. These included bees, ants, beetles, butterflies, flies, and bugs. If, after all, this array of

DANDELION SEED

messengers fail her (as may happen early in spring or late in autumn), she is able to use the pollen from her own flowers as a last resort.

The flower itself is a most interesting structure; looked at closely, it is not a flower at all, but a whole head of flowers, each one of which produces a

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ones the central stem (stigma) is own tube cannot reach the shorter hairs widely split, and curled like a pair on the inner surface of the stigmas, of miniature Dandelion curls, while for each half is covered by the other in the inner flowers the halves of until they separate. As they separate, the stigma are still closely applied to its own pollen is on the under side, and each other and stand erect. Take a close cannot reach the short hairs until the look under the microscope to find why curls make a complete circle, when its this is so. Close around the stalk (style) own pollen may act if the messengers which bears the curls is a five-parted tube have not brought pollen from other flowmade of the boxes (anthers) which hold ers. For the pollen must light on these the pollen dust. Into this tube all the short inner hairs if it is to help make dust is discharged before the stigmas seeds, and pollen from another Dancome out, and as they come out the brush delion flower makes better, healthof long hairs on their outer surface ier, stronger seeds than that from the sweeps the pollen along up above the tube, same plant. where it is easily carried away by insect visitors. Note that the pollen from its

Have you ever noticed that no Dandelion blossoms can be found at dark or on a rainy day? The heads of flowers close except in sunshine, so that the pollen dust may not get wet, for if wetted it is killed, or injured so as to be valueless.

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The stem (scape) on which the flower is borne is a most interesting structure. It is hollow like bicycle tubing, and for the same reason-the greatest strength with the least material. When the Dandelion is in blossom the scape is upright, and just long enough to bring the flower up into a conspicuous position. If the grass be an inch high, the scape will be a little longer. If the grass be a foot high, so is the scape. But when all the little flowers in the big flowerlike cluster have blossomed and there is no more need for calling in insect helpers. and visitors, then the scape bends over toward the ground, nestling the developing seeds close to the leaves and grass, out of the way of the lawnmower or the sharp teeth of the COW or sheep. While the plant babies are growing, secure in their

hidden nest, the scape is slowly but surely becoming longer, so that when the babies are grown and ready to sail away, each in his own little air-ship, this scape straightens up to its full length, lifting the seed infants high in air, so that they may fly farther away and not crowd each other or their parents in their new home. The

sketches of a section through the open and the closed head show how ingeniously the closed heads are made to assume the globular shape SO well known to us. Note in the drawings how the stem, or beak, of the flowers has elon

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gated in the fruit, so that the tiny voyagers may not suffer wreck by being overturned in sudden gusts. Also note on the edges of the basket of this tiny airship the tiny anchor-teeth to catch on leaves and roughened soil. These also probably serve to help force the seed into the soil as the parachute top struggles and rolls and tugs at anchor, until at last it is broken off, leaving the baby Dandelion carefully planted and ready to start into new life. But for all Mo

PLANTAIN HEAD

PLANTAIN ROSETTE

ther Nature's care there is a great deal of tragedy in Dandelion life. Every wellgrown plant will produce some hundreds or even thousands of seeds in a season, but not more than one in a hundred at the utmost will live to grow into a plant producing seed. Yet it is through this very process of selection by destroying all but those best fitted for the conditions of life that the Dandelions of today are so marvellously adapted to existing circumstances.

The common Plantain (Plantago major and P. Rugelii) is another plant that thrives in spite of all efforts to subdue it. It does not make good salad or greens, and in this respect is at an advantage over the Dandelion. It has the same wide-spreading, closely fitting rosette of leaves for smothering competition, the outer with long petioles, and the inner with scarcely any. It also lacks the large, deep root, bitter juice, and conspicuous flowers of the Dandelion. Its flowers are on long slender spikes, without color or odor, and the pollen is hung at the end of long slender threads, so that it can be easily carried by the wind to the plumelike stigmas. These stigmas always appear first, beginning at the

bottom of the spike. After they have caught their fill of pollen they wither, nearly always before the pollen - sacs (anthers) of the same part of the spike are ready to shed any pollen, so that the flowers can very rarely be self-fertilized. The character of the flowers as given above indicates that the Plantain trusts entirely to the wind to carry its messages, but it seems that insects also help, in spite of the apparent lack of inducements. Although the glowing sign is not there, the nectar apparently is, for I have seen bees visit flower after flower and spike after spike, only turning aside for a tempting blossom of white clover. But more than anything else the Plantain depends on the number of its seeds and their longevity. Each tiny capsule produces from five to ten seeds, and there are sometimes as many as a dozen spikes of one hundred capsules each on a single plant, so that a well-developed plant has on it nearly six thousand seeds. A single plant will easily produce fourteen thousand seeds in a season. There is no

COMMON PURSLANE

special device for protecting and scattering these seeds, but from the great number some must get a chance to grow, as they will retain their vitality for years when buried in the ground.

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The common Purslane, or " Pussly" of the farmers, is very different from either the Dandelion or the Plantain. It will not grow in lawns or grass-lands, only in soil that is frequently disturbed by the cultivator or hoe. For it cannot stand competition. Let other seeds grow, and it is soon choked out. If the soil be cultivated often enough to keep down the other weeds, then it spreads itself over the bare soil in thick, reddish-green mats. Attack it with the hoe, and you merely make ten plants where before was but one. The stems and leaves are so thick and succulent that every fragment will send out roots even in the driest of our gardens. If it be dug out, gathered up, and thrown in heaps on the bare rock, the stronger and more fortunate subsist on the remains of their associates. Place a plant in a botanist's

drying-press, and the

lower leaves will drop off, while new leaves will be developed at the upper end.

The thick, fleshy leaves and stems of this plant are characters indicating that it is a native of the seashore, or of arid regions like the deserts of our Western plains. The plants that grow in such situations do not do so because they thrive best there, but because there is little or- no competition. They were probably driven originally to such inhospitable places by the keen competition of their associates, and having had little or no competition since, have lost rather than gained the ability to compete with other plants in more favorable

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