First published June 14, 2021 by Carnegie Museum of Natural History. The genus Smilax is one of our most common woodland plants. Known as greenbriar, sweetbriar, or catbriar, there are about 20 species in North America, and about 300 world-wide. Technically, the plant is defended by “prickles,” which are outgrowths of the outer tissue of the stem, and not “thorns,” which are modified woody branches, as are found on hawthorn or locust trees. By contrast, “spines,” as found in cactuses, are actually modified leaves. Male and female Smilax flowers occur on different plants, with females producing dense bunches of showy black, blue, or red berries. Some species are deciduous and some are evergreen. Light loving, they are typical of disturbed habitats, and will climb up and over shrubs, up to 30 feet high. The green stems have chlorophyll, meaning that even if deer eat all the leaves, the plants will continue to photosynthesize and survive.
Thickets of briars that have their tops bitten off are an indication of severe browsing by deer. When deer densities are high, other plants may be browsed out entirely, leaving behind an understory composed of only briars and a few plants deer do not eat, such as ferns (see post titled “Beauty and the Beast”). Briars may provide good cover for small mammals to escape from larger predators, as is related in Uncle Remus’ African folktales of Bre’r Rabbit. The stout prickles have different orientations along a stem and can be difficult to remove if more than one pierces the skin at the same time. Getting into (and out of!) a briar thicket is a very sticky situation, as we have inadvertently demonstrated after a minor slip-and-fall in the woods!