The Triumph of Seeds (5 page)

The Baskins’ decades of work illustrate just how much there is to learn about what happens inside a germinating seed. Questions raised over 2,000 years ago by Theophrastus, “the father of botany,” continue to challenge scientists. As Aristotle’s student and successor, Theophrastus led exhaustive plant studies at the Lyceum, publishing books that remained definitive for centuries. Working on everything from chickpeas to frankincense, he described germination in great detail, wondering about seed longevity as well as differences “in the seeds themselves, in the ground, in the state of the atmosphere, and in the
season at which each is sown.” In the long years since, researchers have unraveled many of the processes guiding dormancy, awakening, and growth. It is well established that germinating seeds imbibe water and extend their roots and/or shoots through cell expansion. This stage is followed by rapid cell division fueled by the energy in their food reserves. But the exact cues that trigger and coordinate these events retain an aura of mystery.

Germination chemistry alone involves a huge variety of reactions as the dormant metabolism comes to life, producing all the hormones, enzymes, and other compounds necessary to transform stored food into plant material. For avocados, that stored food includes everything from starch and protein to fatty oils and pure sugar—a mixture so rich that nurseries don’t even bother with
fertilizers until well beyond the seedling stage. Transferring my young trees to potting soil, I noticed their cotyledons still clinging to the bases of the stems like pairs of upraised hands. Months or even years after rooting and leafing out, young avocado trees can still eke out a trickle of energy from the lunches their mothers packed. It’s no coincidence that an avocado endows its offspring so generously. Like
almendros
, avocados evolved to sprout in the deep shade of a rainforest, where light is scarce and where massive food reserves can give the seedlings a distinct advantage. Their story (and their seeds) would be entirely different if they had hailed from deserts or high mountain meadows, places where every young plant has a quick path to full sun.

Seed strategies vary incredibly, their shapes and sizes adapted to every nuance of habitat on the planet. While this makes them a fascinating topic for a book, it can also make it hard to agree on just what part of a plant constitutes the seed. For purists, the seed includes only the seed coat and what lies within. Everything outside of that is fruit. In practice, however, seeds often co-opt fruit tissues for protection or other seed-like roles, and their structures become so fused that they’re difficult or impossible to distinguish. Even professional botanists often fall back on a more intuitive definition: the hard bit encompassing the baby plant. Or, even more simply: what a farmer sows to raise a crop. This functional approach equates a pine nut with a watermelon pip or a kernel of corn, avoiding technical distractions about the role of every plant tissue involved. It’s a model well suited to this book, but not without noting just how strangely different the contents of seeds can be.

Because the products of evolution work so beautifully in practice, it’s easy to imagine the process chugging along like some grand assembly line, fitting each cog and sprocket to its particular place, for its particular function. But as any fan of
Junkyard Wars
,
MacGyver
, or Rube Goldberg devices knows, common objects can be reimagined and repurposed, and almost anything will work in a pinch. The sheer ceaselessness of natural selection’s trial and error means that
all sorts of adaptations are possible. A seed may be a baby in a box with its lunch, but plants have come up with countless ways to play out those roles. It’s like a symphony orchestra. Violins get the melody most of the time, but there are also bassoons, oboes, chimes, and two dozen other instruments perfectly capable of carrying a tune. Mahler favored the French horn, Mozart often wrote for flutes, and in Beethoven’s
Fifth Symphony
, even the kettledrums get a crack at that famous da-da-da-
dum
!

With their two hefty cotyledons, avocados illustrate a very common seed type, but grasses, lilies, and a number of other familiar plants have only one cotyledon, while pine trees boast up to twenty-four. In terms of lunch, most seeds use a nutritious product of pollination called
endosperm
, but various other tissues will do the job, including
perisperm
(yucca, coffee),
hypocotyl
(Brazil nut), or the
megagametophyte
preferred by conifers. Orchids don’t pack a lunch at all—their seeds simply pilfer the food they need from fungi found in the soil. A seed coat can be papery thin, like an avocado’s, or thick and hard, like those found inside pumpkins, squashes, and gourds. Mistletoes, in contrast, have replaced their seed coats with a mucilaginous goop, while many other seeds co-opt the hardened inner
layers of the surrounding fruit. Even something so basic as the number of babies in the box can vary, with species from Lisbon lemons to prickly-pear cacti sometimes stuffing multiple embryos into a single seed.

Distinctions among seed types define many of the
major divisions in the plant kingdom, and we’ll touch on them again in later chapters as well as in the glossary and notes. Most of this book, however, focuses on traits that
unite
seeds, joining them in the common goals of protecting, dispersing, and feeding baby plants. Of these, nothing is more intuitive than the last, because, as everyone knows, the food in seeds gets eaten by a lot more things than baby plants.

In the Costa Rican forests where José and I worked, we often headed for the closest
almendro
tree to take our lunch break. Their huge, buttressed roots provided a good backrest, and their spreading
canopies helped to shelter us from both sun and rain. But, just as importantly,
almendros
were the best places around to see wildlife. The stony shells of old seeds littered the ground beneath them in all states of disrepair, split apart by parrots feeding above or gnawed open by various large rodents. When peccaries approached, we always heard them coming, rattling whole seeds against their teeth as they positioned them for a cleaving bite. The sound was like billiard balls clacking against each other.

Raw
almendro
seeds always struck me as a bit mealy and bland. But when Eliza and I once roasted a panful, their sweet nutty scent filled the whole house, and the flavor wasn’t half bad. With a little selective breeding to make the shells more cooperative, I could see them finding a place alongside the walnuts and filberts in our pantry. After all, that kind of experimentation is exactly the process that brought nuts, legumes, grains, and countless other seeds into human larders around the globe. When it comes to stealing the food from baby plants, no animal is more accomplished than
Homo sapiens
, and the importance of seeds in the human diet can’t be overstated. We take them everywhere we go, planting them, nurturing them, and devoting whole landscapes to their production. As Carol Baskin put it, “when people ask me why seeds matter, I have one question for them: ‘What did you eat for breakfast?’” Chances are, that meal began in a field of grass.

CHAPTER TWO

The Staff of Life

Behold, I have given you every plant yielding seed that is on the face of all the earth, and every tree with seed in its fruit: You shall have them for food.

—Genesis 1:29

S
outh Dakota’s Mount Rushmore boasts the huge granite heads of four US presidents. Hillsides in England sometimes feature prehistoric figures—great giants or running horses etched with trenches of chalk. China’s Carved Hills of Dazu harbor thousands of ornate Buddhist sculptures, while the sprawling shapes scattered across Peru’s Nazca Province include monkeys, spiders, a condor, and graceful spirals large enough to be seen from space. In Idaho, the hills have eyebrows. But while that may not sound as grand as giants or presidents, Idaho’s eyebrows rank among the rarest landscape features anywhere.

Standing in the middle of one with my eyes closed, I held a plot frame out in front of me, turned a quick circle, and tossed it. The frame landed with a swish on the steep slope, a plastic rectangle that now enclosed one randomly selected square foot of an endangered ecosystem: Palouse Prairie. I knelt down beside it, opened my notebook, and began to count. The page soon filled as I checked
off nearly twenty different plants crowded into that tiny patch of ground. I saw forget-me-nots, irises, paintbrushes, and asters, but above all there were the grasses—dense green tufts of fescue and delicate June grass waving in the breeze. You don’t need a botany degree to know that native prairies are a good place to grow grass. That is their glory and their downfall, because nothing is more important to the human endeavor than the growing of grass.

Proof of that statement lay all around me, just beyond the edge of the eyebrow, where the jumble of prairie plants gave way to cultivated green fields that stretched to the horizon. They contained grass, too—a tall, Middle Eastern species in the genus
Tricetum
that we know by the name of wheat. All over the world, wherever people go, they take wheat with them; it’s an essential crop now grown on more land than all of France, Germany, Spain, Poland, Italy, and Greece combined. When European settlers reached the Palouse region of northern Idaho and adjacent Washington State, they immediately realized its potential. Formed from ancient windblown sediments, the Palouse’s rolling, dune-like hills held a topsoil ideally suited to grains, a natural grassland where no irrigation was necessary. Plow met prairie quickly, transforming the area into a top wheat producer within a single generation. The few scraps of original prairie that remain lie in places too difficult to cultivate, strung out just below the rims of the steepest hillsides. From a distance, they look like thin, dark lines edging the curved tops of each hill, as if the landscape were raising its grassy “eyebrows” in surprise.

My plant surveys provided the botanical backdrop for an interdisciplinary team of entomologists, soil and worm specialists, and social scientists. The project aimed to better understand and protect the last Palouse prairies and to raise their profile in the local community—grass
pride in a grass place. It gave me a crash course in identifying fescues, bromes, wild oats, cheat, and bluegrasses. Every hour in the eyebrows led to even more time at the microscope as I learned the different species by the subtleties in their leaves and by the various hairs, ridges, and wrinkles adorning their flower parts
and seeds. But while working in the Palouse taught me about grass diversity, it left an even stronger impression of how grasses, and particularly their seeds, have shaped human societies.

F
IGURE
2.1.  The rolling, dune-like hills of the Palouse support fragments of native prairie amid one of the richest grain-producing landscapes in the world. W
IKIMEDIA
C
OMMONS
.

For tourists, grain elevators rising over a farm town represent one of the quintessential Palouse photo opportunities. To locals, they are the economy incarnate—brimming full with the seeds of a good crop, or looming as empty reminders in times of want. During the fall harvest, school attendance drops and the banks in town adjust their signs to alternate between the hour, the temperature, and the spot price for wheat futures. Versions of this same story play out in wheat country everywhere, from the plains of central China to the Argentinean pampas to the irrigated shores of the Middle Nile. And wheat does not stand alone as a grass crop of influence. Corn, oats, barley, rye, millet, and sorghum are also grasses, not to mention rice, the foundation of Asian diets for millennia. In Japan, Thailand, and
parts of China, local words for rice can have telling double meanings: “meal,” “hungry,” or simply “food.” Taken together, grains provide more than half of all calories in the human diet and take up more than
70 percent of the land in cultivation. They include three of the top five agricultural commodities, and they also bulk up the feeds used to fatten domestic cattle, poultry, swine, and even farmed prawns and salmon. When the prophet Ezekiel predicted famine in Jerusalem, he said that God would “break the staff of bread.” By the seventeenth century, the phrase “staff of life” had come into use for all the staple grains, or the breads made from them. In the twenty-first century, little has changed:
grass seeds still feed the world.