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Teaching Tips: Asexual Reproduction in Plants
Sexual reproduction and the unique process known as alternation
of generations characterize the life cycles of plants. Other
strategies for reproducing can also be observed in plants — strategies
that don’t involve the union of sperm and egg. These strategies
involve asexual reproduction, where one parent plant propagates
offspring that are genetically identical to it. While a few animals
can
reproduce
asexually, most do not have this ability.
A potato eye — an example of an asexually
reproducing structure
Have you ever stored
potatoes or onions that began to sprout new parts after a while?
These are great examples of asexual reproduction
in plants. Interestingly, asexual reproduction in plants is most
often associated with food storage structures that the plant
uses to sustain
itself during times of dormancy. The new plant arises from a
bud that exists on the food storage structure. The following
are some examples
of asexual reproduction in plants—from buds in leaves, stems,
and roots.
Leaves
Onions, garlic, and lilies are examples of modified
leaves, called bulbs that serve as underground food storage for
a dormant plant.
After these plants have flowered and the above ground leaves
have fallen away, buds at the base of the bulb represent next
season ’s growth.
Stems
Many plants reproduce asexually from stems—either
below or above ground. Corms, rhizomes, and tubers are good examples.
Corms are short,
rounded stems with buds located at the top. An example is a gladiola.
You can tell the difference between a bulb and a corm by the
presence of leaves in the storage unit of the former. Rhizomes
are underground stems with buds located at the tips of the branches.
Irises produce
these types of rhizomes. Most people are surprised to learn that
potatoes
are actually enlarged parts of stems—mostly occurring underground.
These types of food storage structures are called tubers. The “eyes” on
a tuber consist of a tiny leaf and a bud, which can sprout into
a new plant.
Roots
Sweet potatoes represent storage roots. These structures
include tuberous examples, like the sweet potato, beets, and
turnips as well as longer tap roots, like carrots and parsnips.
On the tuberous examples,
the buds occur above the root or are scattered upon it. On
the taproots, tiny buds exist at the base of the shortened
stem.
Consider bringing some of these examples into your classroom
and starting a garden of plants that reproduce asexually!
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