White oak leaves emerging from the bud in mid-spring

I’ve been enjoying all of the tiny little embryonic leaves emerging from their winter slumbers. One of the strange things is how different the emerging leaf can be in both color and texture from what it will be once it fully expands. Here white oak leaves are fuzzy and brilliantly pink with a yellowish fringe. The fuzz serves the leaves well to insulate them from the cold and prevent them from drying out while they’re still tucked in the bud during the winter. In the summer, the fuzz would just serve to reduce the photosynthetic efficiency of the leaf.

Other plants maintain their fuzziness through the summer at a cost to their ability to photosynthesize. This happens when other factors are more limiting than sunlight, particularly water loss. Mullein – or the more apt lamb’s ears – has fuzzy leaves too. But since it grows out in the open in dry soils it’s got all the sunlight it can get, but not nearly as much water. It can reduce its efficiency and still have all the energy it needs. Nice work, mullein.

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