These seeds determine the survival of an entire species

November 6, 2015, 11:11 a.m.

These milkweed seeds may look like a simple, beautiful seed — but there's more at stake.

We're rooting for them to sprout and flourish because their success determines not only the future of the milkweed plant, but also the future of the monarch butterfly. And there's something important about milkweed seeds that all gardeners and butterfly lovers need to know.

Monarchs are entirely dependent on milkweed for survival. It is the only plant on which monarchs lay their eggs, and that monarch caterpillars feed on milkweed as they grow. It's also the plant that helps make the butterfly toxic to predators, protecting it from being eaten. But widespread use of herbicides and the conversion of land for farming has caused a 21 percent decline in the plant in the United States between 1995 and 2013.

Scientists and conservationists have encouraged citizens to plant milkweed to help offset the loss. However, gardeners have to be careful to plant the correct kind of milkweed. Planting the wrong kind — a tropical variety rather than a native variety — has had a negative effect.

Science Magazine reports: "The problem is that tropical milkweed — at least when planted in warm environments like southern Texas and the U.S. Gulf Coast — doesn’t die back in the winter like native milkweed does. When presented with a place to lay their eggs year-round, many monarchs don’t bother making the trip to Mexico at all ... But it turns out that year-round tropical milkweed presents an even more direct threat to the butterflies. Milkweed hosts a protozoan parasite called Ophryocystis elektroscirrha (OE). As caterpillars, monarchs ingest the parasite along with their normal milkweed meals, and when they hatch from their chrysalises they are covered in spores... Infected monarchs are much weaker than their healthy counterparts and don’t live nearly as long."

So, for conservation-minded gardeners wanting to help monarch butterflies by planting milkweed, the key is to plant native species of milkweed. You can use the Milkweed Finder from The Xerces Society to find out what's best for monarchs and find milkweed that's native to your area.

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Jaymi Heimbuch is a writer and photographer at Mother Nature Network. Follow her on Twitter, Instagram and Facebook.