Pussy Willow in Bloom

Recently I posted a photo of fuzzy white buds on a pussy willow (Salix discolor). Well, the buds have since burst into bloom, and the trails are lined with shrubs covered in fluffy yellow-white flowers.

My coworker Julia (yes, Julia from the porcupine video) and I spent a while examining the flowers on this particular willow, trying to make sense of their anatomy. All we could find were flowers with lots and lots of female parts – no stamens or pollen to be seen.

Finally we figured out what was going on: pussy willows are diecious, with male and female flowers on completely separate plants. The pollen was being provided by the willow growing on the other side of the trail (and yes, there were handsome orange-bottomed bumblebees shuttling back and forth between them).

The other mysterious bit of willow anatomy we puzzled over was the large cone-like structures on the ends of some of the branches. Surely this isn’t what a willow’s fruit looks like?

On a hunch I Googled “pussy willow galls” and sure enough it turns out that these are elaborate galls produced by a tiny midge laying an egg at the tip of an actively growing twig. The midge hijacks the willow’s normal growth and causes it to instead produce layers and layers of leaves at one spot, forming this protective structure around the larva. Definitely one of the most complex and fascinating galls I’ve come across.

I took these photos on Wednesday; this morning we were reminded that by North Woods standards, this is still winter, when we woke up to a thin layer of snow on our cars. Oh well – it seems like just about every year there’s a last freeze after the plants and frogs and everything have gotten started, and they still seem to do all right. Have a good weekend!

Aspen Galls

I promised you a little winter tree ID. Well, clumps of these young trees grow along our trails in abundance, particularly in fairly open areas. Know what they are?

Okay, I kind of gave it away with the title of the post – these are young quaking aspen, Populus tremuloides. Even when they’re this young, their smooth, pale bark and tendency to grow in clusters (the form “clonal colonies,” with many trunks growing from the same set of roots) give them away. They’re an early-successional species, meaning they’re one of the first trees to grow back in an area that’s been disturbed. Another thing to look for is pointy reddish buds. On the trees here, many of the buds have swollen, almost bubbly-looking areas at their bases.

These are galls, caused by a fly called the poplar twiggall fly laying its eggs at the bases of the buds. They’re generally not harmful to the tree.

Do you have aspens where you are? In the fall their leaves turn a beautiful golden color, and as far as I’m concerned they’re one of the most beautiful trees in the North Woods.