Although it’s December in Michigan, yesterday I came across some still-green plants on a hike through a local floodplain forest. While I was unsurprised to find winter-hardy sedges and garlic mustard rosettes, the vine above caught my attention. Known as bristly greenbrier (Smilax tamnoides or Smilax hispida, Smilacaceae), this vine was demonstrating some surprising cold hardiness. Although the leaves were starting to yellow and will probably drop soon, they were still remarkably green after several weeks of below-freezing nighttime low temperatures.
Bristly greenbrier gets its name from its arrangement of thorns. While young shoots are nearly thornless, branches become increasingly thorny with age. The middle-aged branches in the photo above display some thorns, but it’s really the oldest branches that give bristly greenbrier its name:
The fruit had recently ripened, ready to provide winter food for birds that help disperse the undigested seeds: