The flowers of the flame azalea rely on the Eastern tiger swallowtail butterfly to distribute pollen between male parts (anthers) and female parts (stigmas). Because the anthers and stigmas are far apart in these flowers, small insects are ineffective in pollinating them. PHOTO CREDIT: Arx Fortis/Creative Commons Please note: Correct spelling on Arx.

A special relationship between a Georgia butterfly and an azalea

Hundred of spring wildflower species are sporting bright blooms and producing copious amounts of nectar now to entice pollinators — bees, flies, wasps, butterflies, moths, beetles, hummingbirds, bats — to visit them.

The insects and creatures are vital to scores of native Georgia plants for pollination, which is necessary for plant fertilization and seed, fruit and nut production. In essence, pollinators spread pollen grains (which contain sperm) from a flower’s male part, the anther, to the female part, the stigma.

Many plants attract a variety of insects to distribute pollen. Over time, however, some plants have come to rely on a very few pollinators to reproduce.

One such relationship is between the flame azalea and the Eastern tiger swallowtail butterfly, Georgia’s official state butterfly. The flame azalea’s stunning orange and red flowers are blooming now through June in upland forests in Georgia’s mountains and Piedmont.

In most flowering plants, anthers and stigmas are close together, making it easy for pollinators during visits to spread pollen between the two parts.

But in the flame azalea, the anther and stigma are too far apart for bees and smaller insects to come into contact with both organs during visits. Thus, the flame azalea relies almost entirely on butterflies with wide wingspans for pollination.

And not just any butterfly, says North Carolina State University biologist Mary Jane Epps. Specifically, the flame azalea depends primarily on the Eastern tiger swallowtail. A trait of the butterfly is that it moves its wide wings continuously, even while nectaring. “The fanning motion gives the wings a number of contacts with both anther and stigma, making the swallowtails more efficient at pollination,” Epps said in a study in The American Naturalist.

IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The Lyrid meteor shower reaches a peak of about 15 meteors per hour this weekend — in the northeast from about 2 a.m. until dawn. The moon will be first quarter on Sunday. Brightly shining Venus is in the west just after dark and sets about an hour later. Jupiter rises in the east about an hour before midnight. Mars and Saturn rise in the east about an hour after midnight.

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