Plants Class #6: Seeds and Fruit

This was my last real botany class for this group. The next class was just a review, but I will go over that in my next post. I had little time to prepare this class, as outside commitments were overwhelming me at this point. Luckily, seeds and fruit are a pretty easy thing to cover. After all, feeding the kids was a definite requirement if we were going to talk about fruit!

To start things off I asked, What is a seed? 
A seed is the embryo of the plant. It is a new baby plant, often packaged with extra food for the journey, and surrounded by a protective coating to send it on it's way. 

We did a seed dissection so that the kids could see the parts of a seed for themselves. I had pre-soaked some large beans for them to take apart. Lima beans would work great for this. I also had some mung beans and some canellini and black beans. They each got one or two of these and were told to carefully pull them apart and identify the parts. Many of the beans have two halves and this is true for all dicots.

I found several books on seeds at the library, but the one I really like is called "A Seed is Sleepy", and the reason is that the illustrations are terrific. I went through this book with them, pointing out the pictures of different types of seeds and introducing them to the different ways seeds are distributed away from the parent plant. 

After we had cleaned up the seed dissection mess, I gave them a copy of this image (below) and showed them some of the seeds I had collected from around my house. We talked about how each kind gets moved around and why a plant might want to have it's seeds moved around. Some of the methods of dispersal are very clever.

Maple seeds and dandelions are great examples of wind dispersal (we had to stop and go throw some of these "whirlygigs" off the patio). I also had some cotton boles and some grass to pass around.

Animals also disperse grass seeds, but I had a cats claw, a hickory nut, sweet gum balls, and some acorns as examples of this. 

For water dispersal, I had some sea bean and a mangrove seed I had collected in Florida years ago. Coconuts are also a great example of this. One of the kids had supplied us with a green coconut the first week of class, so they had all gotten a chance to see one. 

The previous fall, my son and I had had some fun bursting and collecting jewel-weed seeds. I was able to show them pictures of this, even if I didn't have a real example. If you touch a ripe seed pod, the whole thing explodes.

Finally, humans and other animals can disperse seeds, especially if they are wrapped up in a tempting bit of fruit. Many birds and mammals eat the fruit, seeds and all, and leave the seeds with their droppings wherever they may be.

I brought in a nice sampling of fruit and we talked about where the seeds were in each and how big they were. I also pointed out that many things we call vegetables are actually fruits in a botanic sense. I had a nice selection of whole fruits and vegetables and I would hold up each and ask them, fruit or vegetable? Some of the things I had: apples, strawberries, bananas, kiwi, melon, blueberries, tomatoes, squash, cucumber, sugar snap peas and bell pepper. Also, just for comparison, I had celery, lettuce and beets.

While they were enjoying their fruit snack (I had cut up and pre-prepared a nice selection), I introduced them to the idea of seed banks and why they are so important. A great book for this is The Seed Vault by Bonnie Juettner. 

As food crops become more of a mono-culture and human populations disturb and eliminate habitats, it's becoming more and more important that we try to save the genetic diversity of plants. The best way, often, to do this is in seed banks. This is good protection for the human race as well as for plant species and habitats in general. 

An example of the importance of this is the potato famine that occurred in Ireland in the mid 1800's. The potato had been imported to Ireland soon before, and had done so well that farmers everywhere started growing them almost exclusively. It became the major source of nutrition for at least a third of the population. The problem was that they were all one type of potato. When a potato blight killed most of the crop, more than a million people died of starvation. Today, we know that there are many types of potatoes, so if it happened again, we could try growing some types that aren't affected by the blight or maybe even put the genes that keep some potatoes healthy into the potatoes that we like to eat. 

There are a couple of really large and well-protected vaults, as well as many smaller ones. The history of these is really interesting food for thought. If you want to know more, this book is a good introduction.

If this were a more evolutionarily minded group, I might have gone into Mendel's genetics at this point, but I decided to stop there. They were reminded to review the handouts I had given them if they wanted to do well for the last class. No tests for us, but reviewing is always a good thing!