In the spring, Forty Acre Rock near Lancaster, S.C., goes from drab to dramatic with a burst of flashy colors on a granite outcrop that's the centerpiece of a state preserve.
Small wild plants called elf orpine, black-spored quillwort and pool sprite bloom to showcase a mix of red, green and white hues in shallow, water-filled pools. These rare plants put on their show from March through early May, until the pools dry up and Forty Acre Rock's colors revert to dull grays and greens of lichens and mosses.
The star of this short-lived botanical show is the elf orpine, a tiny succulent that creates what appears to be cherry-red mats on the pools. From a distance, the plants give an other-worldly appearance to the rock, as if a chunk of Mars had orbited in and fallen on the Piedmont.
The preserve, called Forty Acre Rock Heritage Preserve, is open to the public in daylight hours for foot travel only. The granite outcrop covers 14 acres, not 40, and is part of a 2,267-acre natural area and game land that includes 3.1 miles of hiking trails, a small waterfall, a creek and beaver ponds. It is located in Lancaster County, where the Piedmont meets the Sandhills.
According to Exploring the Geology of the Carolinas, by Kevin G. Steward and Mary-Russell Roberson, Forty Acre Rock was formed 300 million years ago when a body of hot magma slowly cooled underground into solid granite. Similar rock outcrops occur from Virginia through the Carolinas to Alabama, including the famous Stone Mountain landmark near Atlanta.
Visitors can enter Forty Acre Rock from two parking lots along the north side of the preserve. The western lot is nearest the rock. It's a 0.4-mile walk along a sandy road through a pine forest. The landscape changes from pine woods to red cedar trees at the edge of the rock. One small cedar that recently died from drought turned out to be about 200 years old. Its slow growth was a result of life in the harsh conditions.
Just beyond the cedars, the upper edge of the massive sloping dome comes into view. Scattered about on the 150-yard-wide dome are depressions formed by weathering of the granite over the eons. Winter and spring rains fill these pools, and as temperatures warm, dormant plants spring to life.
The most spectacular is elf orpine or diamorpha (Diamorpha smallii). Elf orpine stands 1 to 3 inches high, with small fleshy red alternate leaves. The plant has miniscule white flowers. Thousands of elf orpine cluster together, looking like mats covering the pools.
Other plants that can be found in the vernal pools on the rock:
• Black-spored quillwort (Isoetes melanospora). Tiny, green perennials with round, narrow hollow leaves.
• Granite stonecrop (Sedum pusillum). A succulent that resembles elf orpine, except that it has green stems and leaves. It's found in partial shade under cedar trees.
• Pool sprite (Amphianthus pusillus). Tiny, white, solitary flowers bloom between the paired leaves above the water.
• Small's portulaca (Portulaca smallii). A succulent annual with small pink flowers.
Make it a Trip
Forty Acre Rock is about 12 miles east of Lancaster, S.C. Wear sturdy shoes or boots for walking on the rock formation; be careful not to step on the plants or into the pools. For detailed directions to the two parking lots and a description of the preserve, see dnr.sc.gov.