Carl Zimmer in The New York Times:
Throughout his life, Charles Darwin surrounded himself with flowers. When he was 10, he wrote down each time a peony bloomed in his father’s garden. When he bought a house to raise his own family, he turned the grounds into a botanical field station where he experimented on flowers until his death. But despite his intimate familiarity with flowers, Darwin once wrote that their evolution was “an abominable mystery.”
Darwin could see for himself how successful flowering plants had become. They make up the majority of living plant species, and they dominate many of the world’s ecosystems, from rain forests to grasslands. They also dominate our farms. Out of flowers come most of the calories humans consume, in the form of foods like corn, rice and wheat. Flowers are also impressive in their sheer diversity of forms and colors, from lush, full-bodied roses to spiderlike orchids to calla lilies shaped like urns.