“How Flowers Changed the World” is an essay by the anthropologist and nature writer Loren Eiseley that appeared in his 1957 classic, The Immense Journey. I hereby steal Eiseley’s essay title by way of honoring him.
How did flowers change the world? “Once upon a time,” Eiseley writes, “there were no flowers at all.” No roses or dandelions or dogbane or dogwood. A complete list runs to more than 250,000 named species of angiosperms (flowering plants). With flowers the world got its blossoms, its bouquets, its perennial borders, its apple orchards, its peach fuzz, its wheat, its broccoli, its Georgia O’Keeffe flower paintings.
Flowers are sexual organs. Maybe that’s why we find them romantic. O’Keeffe denied that her flower paintings were in any way sexual, which is not too strange considering that she had to constantly deal with the stereotyping of her work due to the fact that she the artist was a woman. (O’Keeffe said, “The men liked to put me down as the best woman painter. I think I’m one of the best painters.”) Still, we must admit that flowers are sexual organs, beautiful sexual organs, and that O’Keeffe’s flowers magnify the details of beautiful sexual organs.
Here’s your flower lexicon for review. Petals. Sepals (the small leaves growing in a circle under the flower, which together make the calyx). Stamen—the male parts. They stick up within the flower, their tiny stems (filaments) each holding one rice-shaped anther, which keeps the pollen. The center part of the flower—that narrow-lipped vase that swells at the bottom—is the female part, the carpel. The top part of the carpel, the stigma, receives pollen. The stigma rests on the style, a hollow tube that leads to the ovary (the bottom of the vase).
Flowers evolved their colors to seduce the pollinators that evolved with them. Hummingbirds go for red flowers; honeybees for yellow or bright purple. A flower’s shape fits the body part used by its principal pollinator to scoop or suck nectar. The ruby-throated hummingbird has a long beak and prefers to dine from the deeply cupped red flower of the trumpet vine. The bird gets food and the flower gets fertilized as the bird spreads pollen from anther to style. Flower scents, too, work to attract. The carrion flower stinks of rotting flesh. The carrion fly, dizzy with the perfume of rotting flesh, lays its eggs in the wrong place (the flower) and pollinates it.
Flowering plants evolved out of non-flowering plants 150 million years ago. This was a very long time after the first land plants evolved 475 million years ago. Land plants evolved from green algae. All land plants have one and only one ancestor (they are monophyletic). First came nonvascular plants, like mosses, which can’t stand up and can’t move water around within their systems. Then came seedless vascular plants, like ferns, which can stand up, can conduct water, but have no seeds. They reproduce via spores, a single cell that can grow into an adult. The adult plant that develops from a spore looks nothing like a fern. It’s a “bisexual gametophyte” that produces a sperm and an egg, which somehow find each other (the sperm is mobile, the egg stays attached to the gametophyte). The fertilized zygote grows into a “diploid sporophyte”—our familiar fern.
Then came the angiosperms with their seeds. A seed is an embryo created via the mating of a male and female gamete, surrounded by food and protected by pod or shell or husk or skin. When pollen meets style, proteins interact, and a pollen tube begins growing down the style toward the egg. The pollen tube reaches the base of the carpel and two sperm exit. They pass through the wall of the ovule and enter the embryo sac. One sperm fertilizes the egg; the other fuses with cells to form the endosperm—the food part of the seed.
Today, looking out my window, I see flowers everywhere. Apple blossoms, cherry blossoms, the white-petaled star magnolia, pale-pink-flowered kinnikkinnick, and forsythia, camellia, huckleberry. Every day now more angiosperms come into bloom. Every day their flowers change the world.
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