I sat eating an apple under the generous crown of an old Douglas fir, the seedlings on the outskirts of its apron a sign that the ground was cool and moist. The brown furrowed bark absorbed the heat and protected the tree from fire. It was thick, too, to prevent water loss from the underlying tissue, the phloem, which transported the photosynthetic sugar water from the needles to roots in an inch-thick ring of long tubular cells. The orange bark of the ponderosas also protected the parasol-crowned trees from the fires that swept through every twenty years or so. These seedlings were growing
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