What’s in a Stem?
What’s in a Stem?
Imagine twirling a daisy between your fingers. Think about
the crisp, green, sturdy stem holding the flower tall.
Now imagine the stem of that daisy is 107 meters tall and
wide enough to drive a car through. No daisy could ever be
that big…but a redwood can.
Though it’s hard to imagine, the stem of a daisy is basically
the same as the massive trunk of a redwood tree. Both help
the plants stay upright. Both help the plants’ leaves and
other structures stay up. Both move water and nutrients
throughout the plants. But that is where the similarities end.
A daisy is delicate, while a redwood is robust. You can snap a
daisy stem in half with a flick of your fingers. You might need
your whole class to link arms to encircle a redwood tree—and
none of you is going to be able to snap that tree in half.
Redwood trees, like most trees, have woody stems. Woody
stems are not as flexible as green stems, but they are much
stronger. Woody stems also help lock in water as it flows into
the body of the tree. However, redwoods also depend on a
continual supply of water from the land around them.
Redwoods cannot withstand decades upon decades of dry
heat. In a desert, a redwood would die from lack of water.
Redwoods can’t live in deserts, but some other plants can.
Deserts present unique challenges to plants. Desert plants
have special stems that help them meet these challenges.
Plants that grow tall need extra protection against the drying
heat. Cacti, such as the giant saguaro of Arizona, have thick,
waxy stems to help keep the water the plant collects from
evaporating. The spines on a cactus stem are actually the
plant’s leaves. Tiny, needle-like leaves don’t lose water as
quickly as large, broad leaves. Although most plants make
food in their leaves, a cactus makes its food in its thick stem.
Both redwoods and saguaros have thick, specialized stems
for surviving in their environments. Redwoods thrive in
moist, foggy areas; saguaros grow tall in hot desert lands.
Discovery Education Science
© 2007 Discovery Communications, LLC
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What’s in a Stem?
Palm trees, on the other hand, have stems that can withstand the
driving force of hurricanes. The stems of palm trees are narrow,
flexible, and tapered toward the top. Because of their shape, they
are more likely to bend rather than break if they are struck by the
high-speed winds of hurricanes.
A stem is a stem is a stem. Some are short and thick, while others
are tall and rigid. Some are woody, and others are green.
But despite their differences, all stems help keep plants alive.
Stems have specialized cells that allow them to hold the plant parts
up. They also have cells that help move nutrients throughout the
body of the plant. Daisies, redwoods, saguaros, and palm trees may
look wildly different, but when it comes to their stems, they are all
very much alike.
Discovery Education Science
© 2007 Discovery Communications, LLC
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