Re: Are cut flowers considered alive?

Dear Janet Kinson's class,

Thank you for your interesting question. Life is a very interesting thing. But what is it? Everyone agrees that a frog is alive, and a tree is alive. But is a crystal alive? Is fire alive? What about bacteria, viruses, and other parasites? Can computers be alive? When does something that was alive stop being alive? First, let's try to define life, and then we can try to figure out if your cut flower fits into that definition.


What is life?

Everyone agrees that life must make copies of itself. Dandelions make more dandelions and squirrels make more squirrels. No scientist believes that rocks are alive, even though some rocks (crystals) can grow. Scientists don't think that fire is alive either, even though fire can reproduce. Fire even has a metabolism!

Currently, there are two groups of scientists that define life differently. One group says that life must (among other things) have a metabolism and be made of cells. This group does not call viruses "alive" but does call everything made from cells "alive" such as bacteria, fungi, plants and animals. Another MAD Scientist, Cheng Huang, has written about life from this point of view.

The other group defines life as anything that can both replicate and evolve. Defining life this way would include even more things than the first definition as being alive. I have written another MAD Scientist essay describing this point of view.


When does a living thing stop being alive?

A living thing stops living when it is not capable of metabolism (according to the first group) or not capable of evolving (according to the second group).

Is your cut flower still able to do these things? If the flower is taking up water, and the stem is still green, it is probably still using its metabolism. It is making sugars from light and air using photosynthesis. So according to the first definition of life, the cut flower is still alive.

Can your cut flower still evolve? Evolution can be seen at two levels. First, the cells of the flower are still dividing. When cells divide, evolution takes place at the cellular level. Then, if the flower is fertilized, and the flower is able to make enough energy from photosynthesis, it may produce seeds. The seeds will show evolution at the organism level.

So your cut flower is alive, by both definitions currently used by scientists!

It's great that you're thinking about such interesting questions. If I can help you out by providing scientific insight, please feel free to ask again!


Yours truly,

John Carlson
MAD Scientist