PLANT LIFE CYCLES
Unit
Overview
If there were no plants on Earth, there would be no life on
Earth. Knowing some plant words is very important in this unit. Germination is
one plant word that will help you when starting this unit. Germination is when
a plant starts to grow. If you were a plant you would never need to eat because
plants make all the food they need. When comparing the life cycles of plants in
this unit, there will be many more plant words to learn about. Plants are
producers and the most important parts of a flowering plant are the
reproductive parts. Roots, stems, leaves, and flowers are parts to remember as
the plant’s reproductive system. Comparing the life cycles of various plants is
the focus of this unit.
VOCABULARY |
|||
observe |
botanist |
vascular |
mature |
cycle |
germination |
producers |
perennials |
repeats |
visible |
biennials |
reproduction |
The twelve vocabulary words above are used throughout unit
eleven. Be prepared to know what the words mean so that you can understand how the
words are used in the unit. Below are some definitions you can practice to help
you understand the words better.
VOCABULARY DEFINITIONS
· observe is to take notice or to watch
closely
· botanist is a person who studies plants
· vascular denotes the system of vessels for
carrying water or nutrients
· mature is when something or someone is
fully grown physically and/or mentally
· cycle is a series of events that are
regularly repeated in the same order
· germination is when a plant begins to grow and
put out shoots after a time of being dormant
· producers is when something is made or created
or grown
· reproduction is to create or recreate a copy of
something or to produce offspring
· repeats is to do something again in the same
way or the same form
· visible is something that is seen or noticed
· biennials are plants that grow every other
year or every two years
· perennials are plants that grow and last for a
long time or more than a few years
The above
diagram is the external anatomy of a typical flowering plant:
Scientists put plants into groups so they can study their
life cycles. There are four basic groups of plants. These four groups are flowering seed plants, cone-bearing seed plants, ferns, and mosses. The three main
differences in plants are their size, color, and texture. The main likenesses
in plants are their leaves and their flowers. What scientists do when studying
plants is look for patterns. These scientists are called botanists. Once
botanists start to observe plants they put them into two classifications known
as vascular and nonvascular. Vascular plants have tubes inside their leaves,
stems, and roots. Nonvascular plants have no tubes. Nonvascular plants have
fewer members in their group. Vascular plants have many members. The best way
to split this group is into flowering and nonflowering plants. This unit will
focus on their life cycles.
Plants grow and change just like you do. Cycles are actions
that happen in the same order again and again. Your life is part of a cycle.
Plants are like you in one respect they also have life cycles. Plants have a
starting period, a growing period, and an ending. A good example would be any
flowering plant. It grows, blooms, produces seeds, and then dies. As new seeds
germinate and grow the life cycle of a flowering plant repeats. One thing to
remember is that different kinds of plants have different life cycles.
Life
Cycle of a Flowering Plant
|
|
(above) The "Typical" Plant Body |
·
Underground
(usually) ·
Anchor the
plant in the soil ·
Absorb water
and nutrients ·
Conduct water
and nutrients ·
Food Storage |
The Shoot System
|
Note:
the shoot system includes the leaves and the reproductive organs. |
A tomato plant is
a good example of a plant with a short life cycle. A tomato plant begins as a seed,
then grows into a plant, produces small yellow flowers, and develops green
fruits as the flower starts to die. When the tomato ripens its seeds mature.
Once the tomato has been picked and eaten (hopefully) the summer season comes
to an end. As the temperatures turn colder the tomato plant dies. If the seeds
are saved and replanted the next planting season, the life cycle of the tomato
will begin again. Any plant that begins as a seed, grows, and then dies during
one growing season is called an annual. This means that plants that grow as an
annual have a life cycle that happens yearly. This is actually a very short
cycle when you think about it! Some annuals can have a life cycle as short as
just a few weeks. Examples of some annuals are flowering plants like marigolds
or zinnias. Some seed plants that would be annuals are beans, wheat, and corn.
Parsley is an example of a biennial plant.
A biennial plant is a flowering plant that takes two years to complete its lifecycle.
There are some plants that complete their life cycles in two
growing seasons or two years. These plants are called biennials. It takes these
plants two years for several reasons. During the first growing season,
biennials not only grow but begin to change. During the first year a biennials’
roots, stems, and leaves develop. During the second year flowers, fruits, and
seeds develop. After the second season the biennials die. Examples of some
biennials are turnips, hollyhocks, carrots, and beets.
Perennials are distinct from annuals in that they return year after year.
The next group of plants to think about is quite different
because of their almost permanent life cycle. Whether it is tulips or trees or
daisies or lilies, the perennial group is one group of plants that lasts a long
time. Roots of these plants are social. The roots and/or bulbs of perennials
stay alive in the ground. The leaves may turn brown and its stems may or may
not be visible. It is the perennials that have hard woody stems that loose
their leaves at the end of summer. Even trees that are 1,000 years old still
have a starting period, a growing period, and an end. Most trees are in their
growing period and can give off seeds for any new trees to start. Whether a
plant exists for a year, two years, or more than two years they each have a
life cycle with a starting, growing, and ending period.
Below are additional educational resources and activities for this unit.