Green 2nd year twig with this year’s growth distinctly different in color (Centennial Woods, Burlington)

Boxelder, Spring’s mood ring

Spring is in the air! Many of our migratory black birds – grackles, red-winged blackbirds, turkey vultures, bald eagles – are back or in the process of returning. And with the all this warm weather, cardinals, titmice, house finches are a-singing and crows are already building nests. I took advantage of Sunday’s springy warm and sunny weather to head out and take some photos of tree buds before they start bursting open.

Right out my door there are a number of boxelders and I was immediately struck with the variability in color this time of year. The most recent 2 years of growth tend to have pretty good range in color, from green to orange to purple. By their third year, the bark turns a pretty drab gray. The unlucky twigs that are killed by insects, deer browse or another cause turn a white gray at the tip and orange lower down (see images below).

Why all the variation in color? This time of year as the temperatures warm and the days are getting longer, the trees are getting antsy to start photosynthesizing. But unless you’re a conifer and still have all your needles, then you’re pretty ill-equipped to take advantage of the weather changes. Putting sensitive leaves out this early puts them at risk of dying in a late frost. Trees are not the wasteful sort and put kick their twigs into action, performing the role of leaves on warm, sunny late winter, early spring days. The difference is particularly prominent in aspens, which change from a winter white to a deep golden spring green. Green ashes turn a beautiful pink. While many many trees photosynthesize in their bark they tend not to be too showy about it.

Boxelder, like aspens and green ash, are not a shy bunch. While colorful year round, this time of year they just start glowing, telling us that spring is indeed here! Here’s an overview of the colors on boxelder:

  • Gray:– 3-year-old mature bark
  • Yellow: Spring is here. On 2-year-old bark in fully exposed twigs
  • Green: On 2-year-old twigs in less sunny spots
  • Purple: On 1-year-old twigs, color results from pigments (anthocyanins) that protect from the sun
  • White: From the waxy cuticle, retained for first year, easily rubs off

Check out the gallery below for the different colors.

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