Category: Trees (Page 15 of 17)

Seed of the Week: Cork Oaks

Last week for the mystery seed of the week I showed a photograph of an acorn. I’m surprised I didn’t get any comments from botanical types, because the acorn itself isn’t a seed. Generally one or two seeds are found inside the acorn casing.

Acorns come in many sizes and shapes, depending on what kind of oak tree they come from. There are over 200 species of oaks found in North America, but the species I’m going to show you today comes from the Mediterranean region. It is the cork oak, Quercus suber.

When my son and I read that cork oaks can grow in Arizona, I immediately called a botanically-minded friend. Yes, she knew where we could see one growing. We hopped in the car.

The first thing you notice about this glorious tree is its unusual bark. The cork bark is used for bulletin boards, flooring, gaskets, and wine corks. As long as it is removed carefully, without touching the cambium underneath, harvesting cork does not harm the tree.

This tree had a rich history. It was planted during WWII when cork was in high demand, but the supplies were largely cut off.

The tree has a lovely, open growth form with gracefully draping branches. I’m afraid my photos were not able to capture its elegant beauty.

Each acorn contains a wrinkly, veined seed.

Aren’t seeds marvelous? Have you ever seen a cork oak?

The Story of Ferdinand

When I see cork oaks, I always think of the book about Ferdinand the Bull with its delightful, whimsical illustrations of the corks on the trees.

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Seed of the Week: Acacia salicina

Did anyone guess last week’s mystery seed?

These seeds are from Acacia salicina, a tree native to Australia but also grown in the southwestern United States. It has various common names, one of which is “willow acacia,” because of its draping, willow-like appearance.

The powderpuff blossoms attract bees and butterflies.

After pollination, the flowers produce these:

Any guesses what the bright red or orange fleshy structures next to the seeds are? Those are very interesting. They are called “elaiosomes,” meaning literally “oily bodies.” The tail-like parts are like a brightly-colored potato chip stuck to the seed. The birds eat the potato chip part and often carry off the seed with it. They drop the seed unharmed when they are done. The seed is thus moved away from its parent or dispersed. Botanically the structure is called an “aril,” which has to do with what part of the plant the elaiosome is derived from.

For a great deal more information about the genus Acacia, see The Unforgettable Acacias

And now, without further ado, the:

I was a little easier on you this week. What kind of plant grows from a seed like this?

If you’d like more information on trees, try these books:

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Tree Leaf Science Activities

Did you do the tree leaf age experiment last spring to see how long tree leaves stay on the tree? Now would be a good time to check your trees. Let us know what you found out so far. Some of the leaves we marked on our orange tree last spring are still on the tree.

If you live where trees are deciduous, you might want to study the next step:  what happens to leaves when they fall off the tree?

First, think about and make a list of what you think might happen. Do you think some might be eaten, or that they will all blow away?

 

Scientists study the decomposition, or breakdown of leaves, by putting leaves in nylon mesh bags and letting them sit on the ground for long periods of time. The researchers come back every few weeks and pick up a few bags to take back to the laboratory. They open the leaf bags up and see what is happening. They look at things like how much weight the leaves lost, what kinds of critters have been eating the leaves, and how the leaves have lost chemicals (nutrients) over time.

You can make your own leaf bags (also called litter bags).

Gather:

  • Heavy duty screen door nylon mesh (1 x 2 mm mesh size is best) or the nylon mesh bags that fruits or onions come in from the grocery store.
  • Equipment, such as scissors, for cutting screen mesh
  • Equipment for closing the screen bag: glue gun or sewing needle and thread (soldiering irons can be used by adults).
  • Place you can safely leave leaf bags under trees and be able to retrieve them over time

If you are using the pre-made nylon bags from the grocery store, you can skip this step. If you are using screen door mesh, cut out strips 10 inches (25 cm) wide and cut into 8 inches (20 cm) sections and fold in half. Use the glue gun, needle and thread or soldiering iron to seal two sides. Leave one end open so you can put the leaves in.

Once you have the leaf bags made, go outside and fill them with leaves. Try to use freshly fallen leaves and collect only the leaves from under the trees where you will be leaving your bags. If the leaves are too dry, you can wet them with a bit of water to get them into the bags without crumbling. The grocery store bags will have larger openings, so you might want to use bigger leaves.

Close the bags with hot melt glue, or by sewing or tying them shut. Place the leaf bags outside in a place where you can safely retrieve them. You might consider marking the bags with sticks in the ground or tying the bags to brightly colored tent pegs shoved into the ground.

Now you have to be patient. Check the bags roughly every month and see how they are faring. Leave them under the trees until next year and then be sure to collect them. Open the bags into a tray or pan and sort through the contents. What do you think you might find?

Other fun activities for fall leaf drop season are to put the leaves back on the tree and exploring fall color.

Do you know what kind of tree this is?

We’d love to hear what you find in your leaf bags.

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