Abstract
THE ovule, which later becomes the seed, is enclosed in the fruit vessel or ovary, the covering provided by the mother plant. During its development, the offspring is protected and nourished by its mother, and the ovule gradually develops into the seed, with its own protective skins or coats, lying within the enlarged ovary, which in the course of time has become the fruit. Examples of fruits with their contained seeds are such familiar objects as the fleshy-fruited tomato with its dry, flat seeds, the broad bean or the scarlet runner with the enclosed seeds or beans, and the Brazil nut, where the mother plant has provided a thick, woody, cannon-ball-like protective fruit-which can only be broken by a powerful hammer or cut across with a saw-enclosing the well-known hard-shelled ‘nuts’Many seeds have been so well protected by the mother plant that the liberation of the seeds contained in the fruit is often a matter of some difficulty. The Brazil nut fruit is perhaps the most remarkable example. In other cases, however, the seeds are shed or scattered from the fruits with the greatest ease when the fruit is ripe, as any gardener knows only too well who attempts to save seed of an Impatiens (balsam), or collect the seeds of gorse, which are shot out from the fruit as if from a catapult. The horticulturist, of course, is concerned only with the seeds when he wishes to replenish his stock of plants. In the majority of cases he merely sows the seed, and germination, that is, the escape of the embryo from the protective seed-coats, takes place sometimes in a few days, sometimes after some weeks from sowing. In the case of willows and poplars the seed will germinate the day after it is sown, and if the minute seed should be kept for more than a few days it will completely lose its power of germination. In other cases seeds may remain viable for years. I remember well the late Sir Michael Foster showing me a pot of Iris, in which the seed was just beginning to germinate fourteen years after it had been sown ! Then there are the seeds of the Australian wattles (acacias), which rarely germinate until a fire has passed over the ground in which they are lying, or which, if sown at home, have to be scraped with a file, or treated with strong sulphuric acid, as is also the case with some other seeds, in order to induce germination, so strong and resistant is the seed-coat. It is known that seeds of Acacia lophantha will germinate after being stored for sixty-eight years and recently, in connexion with inquiries as to seed vitality, we have experimented at Kew with seeds long stored in bottles in our Museum and have successfully germinated seeds ofAnthyllis vulneraria and Trifolium striatum both ninety years old, and seeds of four other leguminous plants, including the Spanish broom (Cytisus scoparius), all eighty-one years old. How long the poppy seed, which germinated and flowered so wonderfully after the shelling of the Somme battlefield, had lam buried in the soil, or how long charlock seed will remain living when buried, we do not really know; but it is truly remarkable that life can persist for so long a time in a body so minute as the embryo of a seed imprisoned within its seed-coats, when the seed is preserved under suitable conditions. What the nature of such life may be, and to what extent respiration, and the other functions we associate with living matter, may be carried on in dormant seeds, is scarcely within the scope of my text, nor could I throw much light on this arresting problem. For the moment we are concerned with the embryo prisoner, whether serving only a brief or a long sentence of confinement, and the nature of the prison.
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HILL, A. Germination of Seeds*. Nature 133, 858–859 (1934). https://doi.org/10.1038/133858a0
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DOI: https://doi.org/10.1038/133858a0