Nature Lab

Watching Out for Tiny Tim

MDC staff monitor geocarpon, a rare plant found in some Missouri glades

Geocarpon (Geocarpon minimum) is a rare succulent that grows no taller than 1½ inches. Also called earth fruit or tiny Tim, it is federally threatened. In Missouri, it is state endangered and found only in sandstone glades. And “not just any sandstone glade,” says State Botanist Malissa Briggler, “but channel sandstone glades.” 

Channel sandstone contains high amounts of magnesium and sodium. Many plants find the resulting salty soil along with the rocky conditions of the glades inhospitable, but for geocarpon, these glades are ideal. Adapted to the shallow, sandy soil, it grows well there, in part because most other plants can’t, which means less competition. 

Briggler and other MDC biologists regularly survey for geocarpon, reporting their findings to the U.S. Fish and Wildlife Service, which reviews the plant’s status every five years. 

“It’s not a long-lived plant,” Briggler says. “You have this narrow window to catch it whenever you’re surveying. After it flowers and produces seed, it dies and turns this rusty red color. And sometimes that helps you to pick it out.”

Assessing the health of geocarpon populations can be tricky because the plant’s numbers can fluctuate wildly from year to year. 

“If it’s been a dry winter or a late spring, we can go out and hardly find any at all,” Briggler explains. “But that shouldn’t be counted as the population declining. Not just after one year. It could have just been a bad year, and then the following year, there’ll be just a flush of it.” 

Within the last few years, MDC biologists have found three new populations in St. Clair County. When geocarpon was first described in 1914, only one population was known. Today about 27 populations are known in the state. 

“Our populations do appear to be stable,” Briggler says, “So, as long as we’re managing the glades well, and keeping them open from getting too much encroachment by cedar and other woody plants, we’ll be able to manage the geocarpon pretty well.” 

At a Glance

When geocarpon was first described in 1914, the only known population in the world was in Jasper County, Missouri. Today about 27 populations are known across seven Missouri counties, and additional populations have been found in Arkansas, Louisiana, Texas, and Oklahoma.

The size of the dots represents the health and stability of the geocarpon population; the larger the dot, the more robust the population is.

After geocarpon flowers and seeds, it turns a wine-red color.