The brown pretzel sticks seen trailside at the Twine Field in Truro are the thick twigs of Ailanthus altissima, the so-called tree-of-heaven, an infamous invasive that has established a grove there. The tree-of-hell, as it is alternatively known, is identifiable in the winter by its giant leaf scars and plentiful lenticels — the scoring and coarse salt in the pretzel analogy — and by its cantaloupe-like bark on older wood. Though it may suggest a snack, this tree is no picnic: A. altissima aggressively outcompetes and kills off native plants and is difficult to eradicate.
