Sprouting Acorns

As I’ve visited schools with my ecologist-in-residence program I’ve noticed some very good acorn crops, what ecologists would call mast. Some naturalists that I have talked with have noted that where they are there are fewer acorns. There seems to be a cycle of good acorn producing years then there are years with little acorn production. It would be interesting to note each year how the acorns are in your woods. If you keep a record of what you find you might note this cyclical change in acorn amounts.

At the Bell Top School in the East Greenbush Central School District there is a tremendous acorn crop this year. I’ve noticed that some of these acorns are already sprouting. These acorns come from the chestnut oaks.

These acorns gave me a chance to explore how seeds grow into trees with the students at Bell Top. I like to explain to them that a seed is really two things – a baby plant (in the case of the acorn, a baby oak tree) and the baby’s lunch box loaded with food packed away by the parent plant (in this case, the parent oak tree). I gathered up some of these sprouting acorns to investigate.

Many of the acorns, like this one, had yet to sprout.

Now and then, as we see here, we’d find one that had a small root beginning to break through the shell of the acorn. The first thing to grow on the young tree is this root. It's called a tap root.

Finding these sprouting acorns made for an excellent use of Billy B’s rhyme from Billy B Sings About Trees (see links to the right) –

The roots grow deep
Deep into the ground
Search for water
Drink it when it’s found

If you carefully cut open the acorn you can see the baby tree, what scientist would call the embryonic tree or growth. Look carefully here at tip of the pointer and you’ll see the embryonic tree, which is slightly discolored and tear shaped. All the rest of the acorn, the white material that fills up the bulk of the acorn is the food that the growing embryonic tree will need. This food was made in the green leaves of the parent tree – remember “Green Leaves Make Food!”

The root will use the food in the nut which is stored in what is called the cotyledons. There are two cotyledons in a oak seed. That’s why oak would be grouped with the dicots, plants with two cotyledons. As the oak seedling grows the cotyledons would form the beginnings of a shoot that would grow from the top of the root. As the cotyledons emerge they grow upward and take on a green color as they begin to produce chlorophyll. And not too soon, for as the food stored in the seed is about all used up the green portions of the shoot will start to produce food for the growing seedling. See my blog for pictures of a maple seedling showing this growth (click on May 2009 in the archives and go to May 24, 2009).