The Coosa Valley Prairies preserve near Cave Spring in northwest Georgia’s Floyd County harbors what is said to be the state’s rarest and most unusual natural environments.

The 929-acre preserve features two dozen small prairies, remnants of a tallgrass prairie that once covered a part of Georgia, and similar to the great tallgrass prairies of the Midwest.

The Coosa Valley Prairies, managed by the Nature Conservancy of Georgia, are characterized by clayey, calcium-rich soil that discourages tree growth — and helps make the prairies some of the most biologically diverse habitats in the state. More than 40 rare and endangered plants and animals can be found there.

But it’s mostly the prairies’ splendid displays of sun-loving wildflowers in both spring and fall that draw Georgia Botanical Society members, including me, there year after year. When we were there in early June, the late spring blooms were breathtaking: a lush garden, it seemed. The preserve’s signature plant of late spring, the prairie purple coneflower, was putting on a magnificent show: Its abundant blooms covered a 6-acre prairie with near solid purple, a stunning sight.

We were back in the Coosa Valley Prairies last weekend, this time to see the equally dazzling wildflowers of fall. The prairies, it seemed, had undergone nearly a complete makeover since spring. Vibrant growths of tickseed sunflower, narrow leaf sunflower, goldenrods, asters, blazing stars and other fall plants now vied for space and sunlight in the open areas.

We found one of Georgia’s rarest wildflowers, the whorled sunflower, blooming in a “wet prairie.” The sunflower was discovered in 1892, but botanists lost track of it, and it was believed to be extinct until Rome botanist Richard Ware rediscovered it in 1994 in the Coosa Prairies. It’s now on the federal Endangered Species List.

Ware, our field trip leader last weekend, noted: “This is such a special place; it’s why I keep coming back so often.”

IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The moon will be full on Thursday. Venus rises in the east less than an hour before dawn. Mars rises in the east about two hours before dawn. Saturn is low in the southwest at dusk and sets a few hours later.