The Triumph of Seeds Read Online Free PDF Page A

live plants that have simply put development on pause, waiting until they land in just the right place, at just the right time, to send down roots and grow.

    F IGURE 1.4.  Avocado ( Persea americana ). Inside the paper-thin seed coat of an avocado pit, two massive seed leaves surround a tiny nub containing the root and shoot. Avocados evolved in a rainforest, where young trees need a large dose of seed energy to sprout and get established in deep shade. I LLUSTRATION © 2014 BY S UZANNE O LIVE .
    For an avocado tree, the right place is somewhere its seeds will never desiccate and the season isalways right for sprouting. Itsstrategy relies on constant warmth and dampness, conditions you might find in a tropical rainforest—or suspended over a glass of water in the Raccoon Shack. With no need to survive long droughts or cold winters, avocado seeds take only the briefest pause before trying to grow again. “The avocado’s dormancy may simply be the time necessary for the process of germination to take place,” Carol explained, “which shouldn’t be all that long.”
    I tried to keep that in mind during the slow weeks before my avocado pits showed any signs of life. They became my silent, unchanging companions: two rows of mute brown lumps lined up on a bookshelf below the window. Although I have an advanced degree in botany, I also have a long history of killing houseplants, and I began to fear for them. But like any good scientist, I took comfort in data, filling an elaborate spreadsheet with numbers and notes. Though nothing ever changed, there was a certain satisfaction in handling every seed, dutifully monitoring its weight and dimensions.
    When it happened, I didn’t believe it. After twenty-nine inert days, Pit Number Three gained weight. I recalibrated the scale, but there it was again, the most encouragingtenth of an ounce I’ve ever measured. “Most seeds take up water right before they germinate,” Carol confirmed, a process cheerfully known as imbibing . Why it often takes so long is the subject of debate. In some cases, water may need to breach a thick seed coat or wash away chemical inhibitors. Or the reason may be more subtle—part of a seed’s strategy to differentiate brief rain showers from the sustained dampness necessary for plant growth. Whatever the reason, I felt like pouring a libation for myself as, one after another, all my avocado pits began doing it. Outwardly they looked the same, but inside, something was definitely going on.
    “We know a little bit about what’s happening in there, but not everything,” Carol admitted. When a seed imbibes, it sets off a complex chain of events that launches the plant from dormancy straight into the most explosive growth period of its life. Technically, germination refers only to that instant of awakening between water uptake andthe first cell expansion, but most people use the term more broadly. To gardeners, agriculturalists, and even the authors of dictionaries, germination includes the establishment of a primary root and the first green, photosynthetic leaves. In that sense, the seed’s work isn’t done until all of its stored nutrition is used up—that is, transferred to an independent young plant capable of making its own food.
    My avocados had a long way to go, but within days the pits began splitting apart, their brown halves tilted outward by the swelling roots within. From a tiny nub in the embryo, each primary root grew at an astonishing pace—a pale, seeking thing that plunged downward and tripled in size in a matter of hours. Long before I saw any hint of greenery, every pit boasted a healthy root stretching to the bottom of its water glass. This was no coincidence. While other germination details vary, the importance of water is constant, and young plants place top priority on tapping a steady source. In fact, seeds come prepackaged for root growth—they don’t even need to make new cells to do it. That may sound hard to believe,