Seattle Times photographer Steve Ringman snapped this portrait of a plant that's instantly recognizable to everyone.

Dandelions inspire strong emotions -- mostly negative in the modern world.

But until the rise of the lawn in the early 1900s, the plants were so valued that prize specimens were exhibited at county fairs. Gardeners would weed out grass to make room for dandelions.

I've always admired the dandelion's tenacity. In late summer, when my lawn turns a crispy brown, only the dandelions thrive. What makes them so hardy?

I found the answers in this online presentation by Anita Sanchez, an environmental educator in New York state and author of "The Teeth of the Lion: The Story of the Beloved and Despised Dandelion."

Native to the Middle East, dandelions were such important medicinal plants that the Pilgrims apparently carried seeds to North America. The plants pack more vitamin C than tomatoes, more vitamin A than oranges and were used as a liver tonic to help cleanse the blood.

In French, the species name translates to "teeth of the lion," possibly because of their tooth-shaped leaves and powerful health effects. "When we weed them out of the garden, we're probably weeding out the most nutritious plants," Sanchez said.

Multiple adaptations make dandelions bulletproof. They're not picky about pollinators. Almost any insect can do the job. No pollinators? No problem. Dandelions have the rare ability to clone their own seed.

Each "petal" on the cheerful yellow heads is actually a separate flower, which produces a seed. Two hundred seeds sprout from a single puff ball, and can be carried up to 200 miles by thermal air currents.

Once a seed hits the ground, it latches on with little barbs. Only one seed out of a hundred fails to germinate. Those tap roots that make dandelions so hard to pull are usually about 3 feet long, though they can grow to an amazing 15 feet.

"If there's the tiniest drop of moisture, the tiniest bit of soil, the smallest crack in the cement, the dandelion can find a way," Sanchez said.

One thing they can't tolerate is shade. Letting your lawn grow three to four inches tall will eliminate dandelions.

But Americans want perfectly manicured grass. We apply nearly 80 million pounds of insect- and weed-killing chemicals to our lawns and gardens annually, according to the National Audubon Society. Much of that barrage is directed at dandelions. Sanchez said her book was inspired by Audubon's estimate that seven million birds are killed every year by homeowners' use of pesticides and herbicides.

Her own rule of thumb for a healthy, chemical-free lawn is one that's dotted with dandelions -- which makes my yard a champion. "If you see dandelions, you can be pretty sure that lawn is good place to let your kids run barefoot," she said.