NATURE NOTE – Number 43 April 28, 2022
Introduction:
Spring is bringing out the flowers and the bees, so let’s discuss…
Our current topic: Pollination
We all learned in school about how the stamen of the flower (the male part) produces pollen and it is deposited into the pistil (the female part) to begin the reproduction part of the flowering plant. We probably learned also that bees were responsible for this pollination. But there is so much more interesting stuff about pollination that we probably didn’t learn. Soo……let’s learn some more.
First of all, let’s talk about flowers of plants. Some plants have the male and female parts on the same flower. Tulip trees and maple trees are like this. Other plants, such as the oaks and hickories, have different sex parts in different flowers on the same tree. Other trees, willows for example, have the male and female reproductive parts on separate trees. Now, you can see that pollinating between trees is more difficult than pollination between flowers on the same tree, or even the same flower.
There are two basic types of pollination – wind and insects. Wind pollination usually occurs amongst plants that produce flowers before the leaves emerge, or at about the same time. This is so that the leaves don’t interfere with the pollen moving into a tree’s flowers. Often these trees produce drooping catkins, or hanging flowers out on the end of a branch. Oaks are good examples, and the catkins appear early in the spring before the oak leaves are very far along. Plants that use wind to pollinate are often taller plants, in a relatively open habitat, that can take advantage of the wind. You may have never noticed the flowers on an oak. They are there, but are generally quite inconspicuous. The wind doesn’t really need to see them in order to disperse the pollen so there is no need to be flashy. Pines and other conifers are wind pollinators, and have separate sexes on one tree. Botanically speaking, conifers do not have flowers but rely on pollen and cones for reproduction.
On the other hand, pollination by insects is a different story. Bright, showy flowers are what attract a lot of insects (and humming birds) to feed on the nectar of the flower. Generally, these plants have both sexes on the same flower, allowing the insect to pollinate while searching for the nectar. These plants are often low to the ground and not exposed to the wind, thus not relying on wind born pollen. Think of wildflowers in the forest or in fields. Not all wildflowers are bright in color. Some flowers (Skunk cabbage, Jack-in-the-pulpit) are dull-colored, but emit a distinctive odor – often unpleasant. It is this odor that attracts the insects – often some type of a fly - and not the bright flower. Many bright flowers have various color patterns (some not visible to the human eye) to help direct insects to the nectar source.
Do all insects pollinate all flowers? No. Some are very specific as to the species of plant they will pollinate, while others are less so. For example, only the Bumble Bee will seek the nectar of (and pollinate) Red Clover. The large Bumble Bee’s tongue is long enough to get through the flower and find the nectar, whereas the smaller Honey Bee has a short tongue and cannot feed on Red Clover. Some flowers are open and accessible, making it easy for insects to find the nectar, while others are more closed and the insect has to work at opening up the flower. This of course causes more pollen to be attached to the insect that can then be distributed to another part of the flower. The amount of nectar in any given flower can vary greatly from day to day, causing the insect to search among a number of flowers before he can find a good nectar source. Tomorrow, it may be a different plant. The nectar is of no value to the flower or plant, other than to attract insects that provide for the pollination.
Nature Opportunities:
Have scouts observe some insects working on some flowers. Also point out that the yellow dust you find all over your car in the spring is pollen from a tree using wind to pollinate. The car just happened to be in the way.
I hope you can use this information in some way to help expose scouts to nature. Unless it is pointed out to them, they will probably never know about all the interesting parts of nature. As always, thanks for visiting Nature Notes. If you have any comments, please email me at:
