Maybe there should be a companion to Aesop’s fable about the tortoise and the hare. This one could be about the spruce and the poplar. Fast-growing trees like poplars might seem likely to win the race to soak up carbon the fastest, making them ideal candidates for tree-planting campaigns aimed at helping to address climate change. But it turns out that slower sprouting trees, like the spruce, are frequently the growth champions. Outside of tropical rainforests or cozy, moist greenhouses favored by labs studying plants, trees that have long been considered “fast” aren’t so speedy after all, according to research published last week in Nature. The findings suggest that tree planters shouldn’t be seduced by the promises of certain trees that might not be best suited for harsh conditions. And it sheds light on a disconnect that has puzzled scientists for years.