The Plateau is home to a variety of evergreen plants ranging from towering coniferous trees like Pine, Hemlock, and Pitch; to shrubs such as the ground juniper, rhododendron, and mountain laurel; and even ground cover that includes partridge berry, trailing arbutis, galax, and Oconee bells, said Highlands-Cashiers Land Trust Stewardship Coordinator Kyle Pursel.
The summit of Satulah Mountain (pictured below) is a great place to see a variety of evergreen plants including trees, shrubs, and herbs. This video was taken Jan. 9, 2021.
To be considered an evergreen plant, it must retain its foliage throughout the year and into the next growing season. Pursel said several areas throughout the plateau make the ideal habitat for evergreens to thrive.
“They tend to be the dominant in three main habitats around here; rock outcrops, slopes with thin-rocky soils, and acidic stream drainages,” said Pursel.
A plant that keeps its leaves throughout winter has two major advantages over other plants, said Highlands Biological Station Educational Specialist Paige Engelbrektsson.
By retaining their leaves and needles, evergreens avoid the enormous energy expense of growing a new set every year, the way that deciduous plants have to. It also allows them to take advantage of opportunities to photosynthesize early in the spring or late in the fall, when deciduous plants have yet to leaf out or have already dropped their leaves.
“Evergreens get a greater return on their investments in each leaf and needle, and can have a longer growing season,” said Engelbrektsson. “Winter is very hard on plants in general and leaves in particular, which is why so many plants are annual – dying out entirely, or deciduous – losing their leaves.”
She added that because winter is so damaging for leaves, evergreens have adapted in fascinating ways. Broadly speaking, their leaves or needles will have a thick coating of fat and wax called a cuticle. This helps to reduce water loss and gives many of them a thick, leathery feeling to the touch.
Water loss can be a problem because as drier winter air moves over a leaf or needle, it can draw water out through small openings called stomata.
Even if the ground is saturated, it can be difficult for a plant to replace this lost water as freezing temperatures can damage the vascular systems that transport water.
Some evergreens can even produce their own sunscreen.
“Another really neat adaptation includes being able to create their own sunscreen using a group of pigments called anthocyanins,” said Engelbrektsson. “When the forest canopy opens up in the fall, evergreens may receive more sun than they do in the summer. The increase in radiation means they may need to protect their leaves. These bronze and purple anthocyanins reduce the amount of light, just like our sunscreen.”
Conifer trees are so named because of the cones that grow on their limbs used for reproduction. Many of the coniferous trees throughout the plateau have another advantage over annual plants, they have needles.
“Needles are actually a highly modified leaf and provide a number of advantages,” said Engelbrektsson. “Most notably, compared to a ‘typical’ leaf, they lose less water and catch less snow thanks to their small surface area. They also have the same waxy coating as many other evergreens, which helps to reduce water loss as well.”
She added that the triangular shape of a conifer tree also keeps snow from piling at the top and weighing it down. The drooping branches often angle downward, allowing snow to fall more easily off the branch. Lastly, conifers have long fiber cells that make their branches flexible and strong, bending instead of breaking under snow.
Good places to see a variety of evergreen plants on the plateau include Satulah Mountain and Sunset Rock, maintained by the HCLT and open to the public. The trail system throughout Highlands Biological Station, including the North Campus and Highlands Botanical Garden, are also good areas to find a variety of evergreen plants.
To learn more about the Highlands Biological Station click HERE.
To learn more about the Highlands-Cashiers Land Trust click HERE.