Freeze. Thaw. Repeat.

The vernal equinox has come and gone and the snow is still on the ground. Despite the frozen earth, we are still seeing (and hearing) evidence that warmer weather is on its way. Some signs of spring include:

• Skanellus is open

• Bluebirds are returning

• Car washes are open

• The smell of skunk is in the air

• Red-winged blackbirds are becoming more vocal 

What is a sign of spring for you?

There are plenty of signs of spring out there but a sure sign for me is seeing this in front of the John A. Weeks Interpretive Center:




SAP. And plenty of it today. This is due to freeze-thaw cycle we've been having. Every sugarer knows that you need freezing nights and warm days for the sap to flow. A day like today is nice and sunny but boy was last night cold.

This process happens every year and every year I'm amazed by the physiology of trees, especially our maples.

As trees start losing their leaves in the fall, they don't need to keep carrying nutrients throughout the tree anymore so all the sap flows down and nutrients are stored in the roots over the winter. When temperatures start to rise in the spring, the sap rises as well. Just like a straw, the vascular tissue inside the tree sucks up the moisture from the soil from the melting soil.

When temperatures at night drop below freezing, it's like the tree gets squeezed and negative pressure is created inside the tree. The freezing temperatures cause everything to contract and when that happens, vacuums are created and those voids need to be filled. Again, think of using a straw. Then, when the sun comes up and the day gets warmer, the tree "expands", creating positive pressure that allows for the sap to flow out of the tree, through your tap, and into your bucket.

If you can't tell from the picture, our bucket is half full. That's pretty good for one night! Our next step is to boil. Here at The Woods we will be using this sap with the first graders in Nature in the City.


Blog post by Anna Leiss

Our First Wildflower

What is our first wild flower of the year?

It’s a plant that heats up and melts its way free of the snow.

It’s a plant with an unusual trick to attract pollinators and possibly keep predators away.

And it’s a plant that grows down pulling itself deeper into the ground each year.

Any day now our first wildflower of the year will make its appearance in the wet areas of Baltimore Woods.

This remarkable plant does not need to wait for the snow to melt, or the sun to warm the ground. This plant is one of the very few that can generate its own heat in a process known as thermogenesis. The heat allows it to thaw the frozen ground and melts its way up through the snow. The plant can warm itself to over 60 degrees F and melt a 10” wide hole in the snow to expose its flowers.

If you were to peer into one of the holes in the snow, you would find a mottled, burgundy / yellow-green colored hood-like cone called a spathe. The spathe will grow to 4-6” and open to reveal the spadix, a small, knob-like flower cluster covered with small yellow flowers.

Because it emerges and produces flowers so early in the season, before most of the usual pollinating insects are active, it uses a distinctive and compelling scent to attract insects. The flower has a pungent smell, usually described as similar to raw meat, and this helps motivate the carrion eating insects to do its pollinating work.

As spring comes, and the snow recedes this plant will get a head start on soaking up the sun’s rays; large brilliant green leaves will emerge in a circle around the flower well before the overhead tree cover can leaf out and block the sun.

If the plant is crushed, it gives off a strong, sulfurous odor that may help keep large animals from disturbing it. Another unusual trait is that it grows down and not up.

Each year its roots grow down and then contract pulling the plant deeper into the ground so that the flower and leaves stay flush with surface and the stem remains below.

In late summer, the leaves will die off and the plant will go dormant until the following late winter/spring.

What is this remarkable plant? It is a member of the arum lily family, known as Symplocarpus foetidus to botanists, and eastern skunk cabbage or just skunk cabbage to the rest of us.

If you go for a hike in The Woods anytime soon, keep an eye out in the swampy areas for this wonderful plant melting its way out of the snow.

Blog post by Jeff Devine