the grace of flowering plants

the grace of flowering plants

Pushing aside forests of cycads and conifers and overgrowing vast fern groves, the angiosperms impressively bloomed across the land about 100 million years ago. Dominating the lands, except where the conifers found refuge up the slopes and away from the Equator, these flowering plants proliferated rapidly as the Mesozoic Era ended, and they continued to diversify during the Cenozoic. Today angiosperms are by far the most dominant, diverse, and recently unique of plant varieties; they are the homes and the source for most of the world's animals.

Before angiosperms, there had been only plants without flowers. The ground had been dominated by mosses and ferns, then forests of palm tree-esque cycads, then forests of coney conifer trees. The advent of angiosperms was dramatic. Today they are the grasses and flowers and fruit-producing trees, most of the shrubs, most of the tropical trees, and almost every kind of deciduous tree. Angiosperms have shaped this age of life on Earth in all but the most plate-tectonically large ways.

About a hundred-forty million years ago, as the single Pangaean continent was splitting south into Gondwanaland and north into Laurasia, a single angiosperm emerged as a new variety of plant. It may have been in what we call China today, but Austalia and Portugal also contain fossils of these early ancestors. The first flowers evolved from leaves and were probably green, the first red fruits evolved around the seed. These early angiosperms were small herbaceous plants adapted to disrupted ecosystems, and after developing through about 40 million seasons around the Sun, they became rapidly more abundant and diverse.

Old Gondwanaland was the location for most of this blossoming. In the Rift Valley between modern Africa and South America, in lower altitudes, perhaps where ocean flooding had killed off the old conifer forests, the angiosperms productively inhabited their niche. Plants had first learned to spread pollen by water, then they learned to spread in wind; the angiosperm began to spread by using the existing flying and eating patterns of insects. Going between similar trees, these insects began to carry pollen on their backs.

More accurately pollinating each other, the angiosperms also produced seeds faster than other plants -- more than once a year. They reproduced fast. These seeds were also double-fertilized, by two sperms, and one offspring was a fruity encasing, which -- by fruit! -- gave angiosperms the fertile range of animals. Thicker plants began to cover more areas, holding more nutrients, more biomass, and more water in the soil. By about 90 million years ago, so quickly that Darwin called their rapid emergence in the fossil record "an abominable mystery," angiosperms came to dominate the land. After about 65 million years ago, the thickest angiosperm forests achieved a closed canopy.

While they drove aside the cycads, conifers, and ferns, expediting the extinction of many old types of plant, the angiosperms also increased both the total mass of life and the total number of Earth's reproducing species. Interactions with the insects and animals became more specific and subtle: by 55 million years ago, the plants had become sophisticated with colors, smells, and nectars, new varieties of organic chemicals intended for both bribe and defense. Today flies like flowers with traps or smells of decay; the bees like the sweet fragrances and yellow, blue, and white petals; while birds and mammals prefer the reddish colors and only a little odor.

The angiosperms diversified the species of certain families of insect -- the first ants and butterflies, termites, grasshoppers, and aphids emerged -- insects who found niches in specific flowers, branches, trunks, and soil spaces. Angiosperms diversified the dinosaurs, doubling the number of species just before the dinosaurs' extinction and proflierating their only surving ancestors - birds. The angiosperms diversified mammals -- shaping tree-crawlers and climbers, swingers, and fliers -- mammals who ate the swollen populations of insects, and partook directly in the new nectars and fruits.

As the climate cooled and dried about 30 million years ago, some angiosperms reached out to cover the the vast stretches of land left by receding forests: the grasses evolved. Again they covered new terrain, inhabited disrupted areas faster, and produced new sources of food.

From the trees, big grazing mammals evolved onto the grasslands. Predators soon followed. Living at the edge of the forest and grassland, a group of primates began to manifest in human-like forms. They were hunters and gatherers, and by 200,000 years ago one strain became humans.

By 50,000 years ago, people moved from Africa and discovered ever-more of the angiosperms' bounty. Grasses provided the wheat, barley, millet, rice, oats, and corn as people became grain-raisers north of the equator after about 10,000 years ago. The legume family provided the beans and peas. The rose family produced plums, peaches, pears, strawberries, loquats, cherries, nectarines, apricots, raspberries, blackberries, and almonds.

People found new fruits in plants around the world. They found that a burst of creativity (about 4 million years ago) on the land somewhere between modern Kazakstan and China produced a bountiful diversity of apples. The first citrus ancestors of oranges came into color on an everygreen tree in the area around Malaysia (about 20 million years ago).

The angiosperm plants have always been our primary sustenance -- we could not exist if they had not preceded us. Photosynthesis by angiosperms provides the food calories for our lives, with almost no exceptions. Ecosystems rooted with angiosperms have until recently comprised most of the components of our habitat. They are our nourishment, home, medicine, and even inspiration.

The beauty of a tomato fruit shaped by humans from the vines of Peru inspired this writing.

Corn and rice fruits from stalks of the grass family, beans and peanuts from the soil-restoring legume family, broccoli from the old mustard family grapes, from the vines of Mediterranean western Asia, and nectar collected from clover flowers by bees, these flowers and fruits nourished this writing.

And for perhaps a third of the paper of this magazine -- all the hardwoods -- we have the angiosperms to thank. Colorful, fragrant, sweet, and inherently sexy -- fast-spreading trees, the makings for us -- thank you.