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Name: katrina
Status: student
Grade: N/A
Location: N/A
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Question:
Why is it that some plants have flowers and some don't have any?


Replies:
Katrina,

You must first ask yourself why a plant produces flowers in the first place.

The purpose of a flower is plant reproduction. Plants produce seeds as the end product of fertilization of an egg with pollen. Seeds are borne in the female part or on the female of a 2-sexed plant species. This means, for example, when you see an ear of corn and know that the kernels of corn are the seed, that the cob is the female part of the plant since it is holding the seeds. The male part of the plant is that which produces the pollen; in the case of corn, it is the tassel at the top of the plant.

Back to your original question... Sometimes plants produce very small flower structures which are not really visible unless you look closely for them. Others, like a dogwood tree, produce a showy display most people would call a flower, but only a small part of the pink-or-white "flower" is actually the flower used for reproduction, i.e. male and female parts. This time of year we see a lot of spring flowers in the garden, and the different sex parts, male and female, are easily identified.

Some plants are specifically developed to produce no seeds. Some types of grapes and bananas would be a good example. While some types of grapes have seeds inside, many people prefer eating grapes which have no seeds. In this case, plants are developed which, under normal conditions, will have flowers but will not produce seeds. As mentioned above, we also would like to continue having bananas without pits. ;)

There is an entire process by which a plant enters into its reproductive mode instead of its normal vegetative mode (that is, just regular growth). There are hormones involved and a series of unbroken events needs to occur for the plant to successfully flower and produce seeds. Simply stated, for those plants which do not flower, some step in the process never occurs and the plant therefore does not flower. In some cases, a plant may be too young and not mature enough to flower. In other cases, the plant, through nutritional or developmental insufficiency, is unable to complete the entire process needed to produce flowers and/or viable fruit. Again, one needs to carefully observe plants because frequently the flowers are inconspicuous even though seeds somehow "appear" on the plant later in the season. Bottom line....if you DO find fruit on a plant, you know that there HAD to be a flower at some point which produced that fruit.

One thought question.... you are probably accustomed to seeing green grass in the yards in your neighborhood. You might ask yourself, why doesn't the grass produce "flowers"?

Part of the reason is that we interrupt the development process of grass by mowing it. If we left it alone, it would grow tall and then "go to seed", producing grass seed at the top of the plants.

An interesting question!
Thanks for using NEWTON!

Ric Rupnik


Both provide different modes for plant reproduction:

http://en.wikipedia.org/wiki/Reproduction

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AsexualReproduction.html

http://library.thinkquest.org/22016/contribute/asex_sex.htm

Anthony Brach Ph.D.


An intriguing question - evolution and adaptation have produced many different ways of living, those that work survive and those that don't disappear. Flowers provide many advantages for successful reproduction, and flowering plants dominate the flora in most parts of the world. Non-flowering plants still succeed in many places and continue to survive. A great discussion that is very easy to understand is in the book

Flowers and How They Changed the World, by William C. Burger

J. Elliott



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