How Plants Spend The Winter At Arabia Mountain

The leaves have fallen, temperatures are dropping and winter is rolling in once again at Arabia and Panola Mountains. The unrelenting heat on the rock is finally gone and the plants that inhabit them enter a different stage in their life cycles. A stark contrast to the summertime, winter on the outcrop at Arabia and Panola Mountains brings with it a different way of life, one that the flora is adapted to just as much as it is to summer. And unlike most other places where winter is a time of dormancy and inaction, here it is a time of flourishing for many plants.

Diamorpha

Many outcrop-dwelling plants do their growing in the cooler and wetter winter months, when vernal pools retain water and solution pits (eroded indentations in the outcrop rich with sediment) stay moist. For them, summer—when temperatures on the outcrop can reach over 115°F—is what winter is to most other plants: a time to hibernate and wait out the season.

One such plant, diamorpha, Sedum smallii, begins to emerge in the winter despite being known for its springtime emergence and stunning white bloom, albeit in a less showy fashion. One of the signature plants at Arabia and Panola Mountains, this unusual succulent, endemic to the Southeast’s Piedmont Region, has based its entire life cycle around the seasonal cycle on rock outcrops. Because of this, it is actually exclusive to these environments, which can be found around the Georgia Piedmont. Diamorpha belongs to the Sedum species, also known as stonecrops, which are succulents. These plants, like cacti and aloe, have fleshy features which retain water, allowing them to thrive in dry environments.

However, the summer heat also poses a threat to its delicate seeds. Diamorpha’s trick involves holding on to its seeds until after the heat dies down. After emerging in the winter, diamorpha grows slowly throughout the winter and spring, reaching its peak growth around April and May, putting on its display of white flowers for several weeks, then withering into small, gray twigs. The seeds drop once temperatures cool off in the fall and more consistent rains pick back up. Diamorpha takes advantage of wintertime to grow and is perhaps the most well known plant at the Heritage Area to do so. Learn more about this rare plant.

Snorkelwort

The snorkelwort, pool sprite or little amphianthus, Gratiola amphiantha, is another outcrop plant and has a fast life cycle which has adapted to accommodate for winter growth. It gets its name from the way it grows in pools: growing up from the bottom to the water’s surface, its leaves sticking out of the water like the air tube of a snorkel. Because of this it relies heavily on rainy conditions to fill up its pools.

After germinating in early winter, the plant counts on rain to provide it with water for growth and habitat which fills the vernal pools on Arabia Mountain’s rock outcrops. The plant will grow during wintertime and produce leaves and tiny flowers on the surface of the pool’s water. By April, the plant will have produced flowers and “fruit,” which contain seeds that remain dormant as the pools begin to dry with the warming weather, ending the snorkelwort’s life cycle. The seeds stay dormant through the hot summer months, hidden in the dirt which protects them from drying up. During certain years, when drought conditions are high, seeds may not even sprout at all. The cycle repeats as temperatures drop once more and the late-fall and winter rains return. Like diamorpha, snorkelwort gets most of its growing done in the winter.

Black-Spored Quillwort

It may look like grass, but black-spored quillwort, Isoetes melanospora, is actually a fern. It’s another unusual outcrop dweller that grows in vernal pools and is endemic to Georgia’s Piedmont region, with some historic reports of populations in South Carolina. The plant is evergreen, does not flower, and reproduces via spores that are stored in the base of the leaves. The spores drop out when leaves dry in the summer due to heat and inadequate water. It is adapted to rapidly regrow its leaves once a shower comes through, allowing it to live through long dry spells. In winter, the plant usually has a more comfortable experience, with less frequent droughts and lower temperatures that keep their pools filled with enough water.

Pines and Evergreens

Other evergreens, like the loblolly pine, are drought tolerant and don’t go dormant. They have found ways to conserve water, like the pines’ needles which have less surface space than typical leaves and therefore keep water from evaporating as rapidly. Their life cycles tend to be more static, with less dramatic changes seasonally. Evergreens are adapted to take the summer heat, the winter cold, droughts and times of abundance of rains, allowing them to live in limiting environments like the thin soils on and around outcrops. They have found their own way of staying alive where many others cannot, even in different seasons.

Learn even more about the National Heritage Area’s plants and many of their unusual characteristics. Arabia Mountain might be a giant, solid-rock mass, but its ecosystem, especially the solution pits and vernal pools, are quite fragile. So please watch your step while visiting and, as we like to say, “stay on the gray.”