Science :Botany - Ferns

I found it difficult to complete this chapter on ferns without mentioning the concept of the alternation of generations in plants. In the end, I decided to introduce it to my boys. These are some useful sites:

• an definition of terms used in the alternation of generations
  
• a worksheet that could be used with some modification
  
• clear diagram relating to the alternation of generations in ferns.
• a simple review game of the life cycle of ferns.

My objective is to expose them to the concept. I didn't want to overload them with technical terms.

I found a good diagram in one of my old Biology books called Botany: An Introduction to Plant Biology by Mauseth. (Here is another good diagram.) It shows the haploid and diploid parts of the fern in its life cycle. I found the easiest way to get my boys to understand this complex concept was to let them colour the diagram; using yellow colour to indicate the parts that are haploid (with one set of genes) and green colour for the diploid(with two sets of genes) parts. The "ah-ha" moment came as they were colouring.


From there, I could then further make a comparison between the spores of the ferns and the seed of flowering plants. They are not quite analogous. The spore is haploid while the seed is diploid, the result of a fertilization process.


We collected sporangium from our fern to view under our Brock Magiscope (mag:200x). I managed to capture it on my camera just by positioning the camera directly over the eyepiece!


You can see the thin side walls of the sporangium and the very faint outlines of the spores within. The cells surrounding have jointed rings (annulus) that will strighten hygroscopically to break the thin side walls, throwing out the numerous spores within. We left the whole set up as is to continue with our other activities for school. Three hours later, this was what we saw. The sporangium opened!



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