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Flowers or Not
Name: katrina
Status: student
Grade: N/A
Location: N/A
Country: N/A
Date: N/A
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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Update: June 2012
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