Frostweed exhibiting crystallofolia at the Tenison Park Pollinator Garden. Photo by Karen Albracht.

When freezing temperatures arrive, plants have different survival strategies. Some die. Some go dormant. Some lose their leaves.

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Those signs are visible. But there’s one plant, which can be found at the Tenison Park Pollinator Garden, that seems to play a trick on us.

It’s a perennial called frostweed. In the garden, it provides nectar for Monarch butterflies as they migrate south to Mexico, according to Karen Albracht, the administrator of the garden. And its seeds are a food source for winter birds.

Frostweed looks like it’s dormant in the winter, but it’s not because its roots are still active. Above the surface, a unique phenomenon — crystallofolia — can sometimes occur on the base of the plants’ stems.

Crystallofolia refers to the random formation of ice crystals from water emitted along a stem near the ground level of plants, including frostweed. It can be best observed in the morning before the ice melts.

As seen in the photo at the top of the story, pressure from freezing caused the outermost layers of the stem, the epidermis and cortex, to rupture.

There is a volunteer opportunity at the garden Saturday, Jan. 8, at 1 p.m., weather permitting.