As the population grows and temperatures rise it will become more difficult to grow enough food for everyone. So, scientists are exploring the planet for plants that do not need as much water as today's crops. The Mojave Desert in the U.S. state of California is home to some of these plants.

Scientist Heather Rose Kates of the University of Florida is in that desert. She is searching along roads for a plant called the coyote melon.

"We've spotted it here right along the ground. Nice yellow fruits."

Coyote melons are in the same plant family as butternut squash, zucchini and pumpkins. Those vegetables are popular around the world.

Ms. Kates is not collecting the coyote melon for its flavor, which she describes as terrible. She says it contains cucurbitacin which is bitter.

Coyote melon may not taste good, but it can be grown in places that have had little rainfall. The desert where it grows gets just 15 to 20 centimeters of rain per year, or less. Other kinds of squash need at least two and a half centimeters per week to grow.

Scientists are considering combining wild coyote melon with regular squash to see if they can make a tasty vegetable that doesn't need as much water to grow. That could be useful on a planet growing warmer and more crowded every day.

Andy Jarvis works at the International Center for Tropical Agriculture.

"The world is facing a real challenge in terms of food security over the next few decades."

Mr. Jarvis says farmers will need to produce 50 to 70 percent more food by 2050 to feed the world. So, he says, researchers are studying the wild versions of farm-grown crops.

But he says there is a problem. He says many wild versions of farmed plants are disappearing. He says they are threatened and scientists have not collected their seeds for future use.

Scientist Kates is part of an international effort to gather these plants and save their seeds while it is still possible.

Workers are collecting wild oats in Cyprus, wild potatoes in Argentina and wild peppers in Paraguay.

The plants and seeds will be sent for storage to the Global Seed Vault in Norway and at Kew Gardens in Britain.

Ms. Kates spends most of her time in a laboratory. She says gathering plants has helped her understand more about them.

"And it's really only once you're out here looking at the wild plants -- which are where our crops came from -- that you get to see what they can do."

I'm Marsha James.