Thursday, April 19, 2012

Little leaves

What: Quiz Time! This seems to be the hardest part of the year for telling which trees are which: the buds are bursting, becoming unrecognizable, and the little leaves, just emerging, haven't quite yet taken full shape. It's like looking baby photos of friends and trying to guess who they are. The leaves in the photos below are some of the early ones to come out. Roll over each to test your ID skills (there are both shrubs and trees). 

Quaking aspen (Populus tremuloides) Alternate leaf dogwood (Cornus alternifolia)
Common buckthorn (Rhamnus cathartica) Red maple (Acer rubrum)
Staghorn sumac (Rhus typhina) Norway maple (Acer platanoides)
Male boxelder (Acer negundo)Boxelder (Acer negundo)
Siberian elm (Ulmus pumila)

Ecological notes: You can compare the male boxelder shown above to the female boxelder from my post on boxelder bugs. Also, the last photo shows the seeds from an ornamental Siberian elm in Centennial Woods. Ryan Morra and I were pondering over greenness of the seeds. One possibility is that they're actually photosynthetic when they're young (boxelder, white pine, oaks, walnuts, and probably other seeds that invest a lot in endosperm are also green when young). I would imagine that this would take away pressure on the leaves to produce energy for the developing seed. In the elm photo it's a fly on the seed, but other pests can destroy a seed. If leaves were producing energy for growth, winter storage, and the seed, they might be more likely to be at a net loss each year. Having seeds responsible for their own growth is energy insurance for the rest of the plant.

Spoiler alert: The species above are, in order, Populus tremuloides, Cornus alternifolia, Rhamnus cathartica, Acer rubrum, Rhus typhina, Acer platanoides, Acer negundo, Acer negundo, Ulmus pumila.

Other notes: Just a pattern I noticed - willow family and maple family seem to be among our earliest trees to leaf out. Big-tooth isn't out yet, birches are barely opening up, and the buds on some of our more southern species are only beginning to open (e.g. walnut, oak, hickory)


  1. Teage - have you noticed, though, the the SUGAR maples are only now starting to break bud, though? True about the reds, striped, and boxelders, though. Now into the final part of April, I have noticed that the black cherries are the next on the list to be leafing out. I also noticed the butternut planted at the north entrance to centennial is coming out.
    Let figure out exactly when and how each of these trees form their buds - that's something I want to know more about!

    1. I have noticed that. I also noticed that the beech leaves are just now swelling up. Black cherries I noticed leafing out a couple of weeks ago, at least in my backyard. I'm also curious about the marcescence in beech. At what point do those dead leaves that stay on the branches all winter fall off - as I never seem to see any dead leaves from the year before.