Wednesday, July 31, 2013

Plants Class #5: Flowers and Pollination

This was a fun class, and not quite as packed with information. The timing was about right, though maybe a little early, as we did this class in the Spring. By early March flowers were starting to bloom and the yellow pollen was thick on everyones patios and cars. I was able to collect a nice bunch of flowers, plus I went to the store and got a few cut flowers that we could take apart.

As I usually do with these classes, I started with an essential question. Why do plants make flowers? What are they for? I got back a range of answers. Some were "Ummm... because they are pretty?" and some were more, "So bees can have food." or "To make more plants!" Bingo! 

Essentially, flowers are where the plant makes seeds. The point of a flower is reproduction. Many plants have flashy colorful petals to attract pollinators, but some have very unnoticeable flowers. They may rely on smell, wind or pollinators that don't fly.

I gave them a hand-out at this point and we went over the different things that pollenate plants and the different ways plants get those things to do that job for them. 

First off, we have wind pollinated plants. This has a fancy name: anemophily. Most gymnosperms and a few angiosperms use this method. Many wind-pollinated plants are also allergens. Some common wind pollenated plants in our area are pines (that lovely yellow coating we get every Spring), birches, oaks, ragweed and grasses.
pine                                                                                        ragweed


oak
grasses
You'll notice that most of these have flowers that are not showy. There is no reason to spend energy on showy flowers if you are just counting on the wind to move the pollen around. Pollen from male cones or spikes needs to somehow get to the female cones or spikes in these cases, so that seeds can form. In some cases, both will be on the same plant, and in some cases there will be male plants and female plants. 

Other kinds of plants have both male and female parts on each flower, and flowers can be self-pollenated or cross-pollenated.

Other than the wind, insects are the most common pollinators, and of these, bees and butterflies do 80% of the work. Bees are by far the most important insect when it comes to pollination, and we rely upon them for many of our crops.

The single largest pollination event in the world is in the California almond orchards, where about one million hives are trucked in each spring to do the job. New York's apple crop requires about 30,000 hives, and Maine's blueberry crop uses about 50,000 hives each year (from Wikipedia: Pollination).

Day pollinated flowers tend to be colorful and flashy. Many offer sugary nectar as a reward. In return, the insect unwittingly carries the pollen from flower to flower. Bees drink nectar but also gather pollen to feed their young and make honey with (which is food for getting through the winter). There are many types of bees. You many also find beetles or other bugs also feasting on what the plants have to offer.

Long tubular flowers can only be pollinated by things with long tongues, like hummingbirds. Hummingbirds also tend to like the color red, so many of these flowers are also red. 
Some plants like moonflowers use moths to pollinate, and many only open their flowers at night.
The rafflesia flower (Rafflesia arnoldii) is the largest in the world and it smells like rotting meat to attract flies.

Occasionally, bats, geckos and mammals are also known to be pollinators.



The next part of the class involved going over the parts of a flower and doing a flower dissection. I handed out some little booklets I had made up for them. On the front was a flower diagram with the parts of the flower labeled. Inside was an unlabeled diagram. I gave them each a flower or two to pull apart and they were to find each flower part and label the inside diagram of the booklet. I asked them to also tape one of each part onto the inside as well. 

They really enjoyed this, and I enjoyed the big pile of flowers all over the table. 


While they did this, I explained that the pollen grain would go down the stigma to the ovary and then the seed could start forming once the pollen and egg had merged.The diagram they had had both "male" and "female" parts labeled on it. I also explained that flowers like sunflowers were actually multiple flowers in one.



They had tulips and another kind of flower (I can't remember the name) to compare and I asked them if they could tell me if the flowers were monocots or dicots. The tulip is a monocot and has flower parts in threes. Some of the kids had brought some additional flowers to class, and we looked at these as well. I asked them to notice differences between the different flowers. 

For homework, they each got a flower parts sheet to color. This way, hopefully they would review the flower parts I had just given them. I got the sheet at Docstoc.com, which seems to have a good selection of materials. Here's the link.






1 comment:

  1. Great! I love learning more about flowers and plant!!! flowering plants December is part of the dormant period, but “the lotus are going to come back,” McDonald said.

    Still, the flowers’ health is a sensitive subject to locals. When Echo Park Lake reopened earlier this year after a $45-million makeover, people flocked to see the newly installed lotus plants, which were making their return to the lake after a multiyear absence.

    As recently as 2005, the lotuses stood five feet high and spilled onto the shore. But about seven years ago, the flowers started to shrivel and the leaves began to brown. By 2008, they had disappeared.

    Some people blamed the lake’s dirty water, others accused natural predators — fish, turtles and crayfish. A crew of biologists did a study, but they never pinpointed a cause.

    The plants were restored recently under a veil of black protective mesh and hundreds of Angelenos ...............

    ReplyDelete