From Seed to Seed:
a seed alive? Because seeds show no signs of life-no signs of discernible
metabolic activity-it is hard to imagine them to be living organisms.
In fact, not only is a seed alive, but even the tiniest seed contains
all of the necessary information and resources to begin a new life. Consider
the analogy that "a seed is a plant in a box with its lunch." This is
a perfect way to think about the seed. Inside the seed coat, there is
an embryonic (baby) plant composed of an embryonic root, stem, and leaves.
In addition, the seed contains a food supply (called the endosperm)
that is jam-packed with proteins, oils, carbohydrates and vitamins. This
food supply will keep the embryo nourished. As the embryonic plant develops,
the seed leaves-or cotyledons-absorb
the food supply and continue to nourish the plant. Once the true leaves
appear, the cotyledons are off the hook as the plant begins to make its
own food through photosynthesis.
With their hard seed coats protecting the delicate plant embryos within, seeds are miracles of evolution. Many seeds are able to endure long periods of drought, heat, or freezing temperatures-yet are ready to spring to life when favorable conditions arise. Depending on the adaptations that they have made to survive in their native environments, different plants' seeds may require darkness, light, warmth, chilling, mechanical abrasion, or even exposure to fire before they will germinate.
Made possible by a grant from Oracle Corp.
Copyright 2001, National Gardening
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