GROWING PLANTS IN THE GARDEN
Traveling Seeds LESSON
Content Objective: Understand
how seeds travel
Life Skill Objective: Learning to learn through observing, experimenting, and
Have you ever noticed an area where the soil was just turned or tilled, then came back a coupleweeks later and saw that weeds had begun to sprout? How did those weeds get there? The plants did not walk, fly, swim, or crawl to the bare soil, but their seeds got there somehow and began to grow. If all plants simply dropped their seeds right below the “mother plant,” the area would become too crowded and most of the plants wouldn’t survive. Seeds move around in various ways.
DO (15 minutes)Teacher Note: Give the students one Post-It. note each and have them stick it somewhere on their clothes. Tell them that it will fall off somewhere in the classroom and that they are to leave it where it falls. Also have the Whirly Gig Patterns, tub or bowl of water for coconut or sunflower seeds, and confetti in the envelope or bag ready to use.
(Write .hitchhiking seeds. on the board. Have the students walk around the room or move in their chairs until their sticky notes fall off.) Have you ever been out for a walk in the woods or tall weeds during the fall and you came home with hitchhiking seeds stuck on your socks, pants, and shoestrings? Do you have a dog or cat that has romped in the weeds until its fur became full of tangles and seeds? Hitchhiking means trying to get a ride from one place to another. Hitchhiking is one way seeds move from one place to another. Your sticky note hitchhiked on your clothes until it was brushed off or fell onto the ground.
(Write .airborne seeds. on the board. Distribute the Whirly Gig Patterns and follow the instructions to makethe Whirly Gigs.) Have you seen seeds such as dandelion or maple tree seeds floating in the air? Animals carry a lot of seeds around from place to place, but more are carried in the wind. When some seeds are ripe, they fall off the tree or plant, spin and whirl, and are airborne or carried away by the wind. Stand beside your desk and hold your Whirly Gig way above your head. Then watch it spin and whirl to the ground like an airborne seed.
(Write .floating seeds. on the board. Have the students stand around the tub or bowl of water.)Some seeds float away from their parent plants. Have you ever seen seeds floating in a puddle, along a shore, or in a creek? Let’s see if this coconut or these sunflower seeds float. (Have the students try floating the seeds.)
(Write .exploding fruits. on the board. Hold the envelope or bag of paper with confetti up so everyone can see.)Some seeds explode out of their seed pod and scatter all over. The seed pods are like loaded cannons. When the seeds ripen and the pods dry, the pods split open with force, flinging the seeds in all directions. Let’s imagine that this envelope or bag is a seed pod and the seeds inside are ripe. We’ll rip open this envelope and see where the seeds scatter.
AN IDEA FROM HITCHHIKING SEEDS
Have you ever had shoes, hats, gloves, or other things that close with Velcro™? George de Nestral took the idea from seeds and fruits that have hooks that cling to fabric and fur and invented Velcro™!
REFLECT (10 minutes)Hitchhiking Seeds: How are hitchhiker seeds like the sticky note you’ve been wearing on your clothes? The sticky note was stuck on your clothes until it was brushed off or fell somewhere. If it was a seed, the sticky note would have been planted where it fell and it may have eventually grown a new plant.
|Some hitchiker seeds
have hooks or stickers on them. Sticktights are small, flat fruits that
look like seeds. There is one
seed in each sticktight fruit. The fruit has sharp points or barbs that
hook into your clothes. If you pull
the sticktights off of your clothes while you are outdoors, you
have moved the seeds to a new location where they might grow. Animals move
the sticktights from place to
place on their fur.
The dried flower head of a burdock is a small ball that is covered with stiff, sharp hooks. A burdock burr is hard to get rid of because it sticks to your fingers when you pick it off your clothes! They are a real mess when they get tangled in hair and animal fur! The seeds of the burdock are tucked inside the burr and are scattered when the burr is broken.
Queen Anne’s Lace is a common weed found in ditches. The small fruit on this plant has rows of tiny spines or hairs. When it is ripe it gets stuck on the dry fur of animals and is carried away.
A common lawn weed, plantain, moves its seeds in a strange way. When the seeds that form on its tall spike get wet on a rainy day, their outsides become sticky like jelly. The jelly-covered seeds stick to anything that brushes up against them.
What other ways do seeds hitchhike with animals before the seeds are planted? What dosquirrels do with the acorns and nuts that they collect? They carry them away from the trees and bury them. Some of these buried seeds grow into large trees. What happens to the seeds after bears, birds, raccoons, and other animals eat berries and fruits? The seeds pass through their stomachs and are spread in their scat or feces. Have you seen purple bird droppings that came from a bird that ate berries?
Teacher Note: Picking up hitchhiking seeds
|Airborne Seeds: What
happened to your Whirly Gig when it floated in the air? What if you
added a little wind when you
released your Whirly Gig? Have you seen seeds floating in the air?
What plant did they come from?
The flowers of some plants such as dandelions and thistles dry so that there is light, fluffy fuzz on the ends of the seeds. This fuzz becomes a parachute that can carry a seed for miles on a strong gust of wind. Milkweed also spreads its seeds with fuzzy parachutes. Each milkweed seed has about 900 silky hairs that are light and hollow. When the milkweed pod splits, the wind catches the fluffy hair and pulls the parachute and seed out of the pod, sending it floating in the breeze.
Some seeds have special wing-like parts that catch the wind and get carried away. Maple, ash, and elm trees have seeds that twirl in the air like helicopters. The seeds are formed on branches high in the tree. When the seeds are ripe, they fall off the tree, spin and whirl, and are carried away by the wind.
Some plants such as columbine and poppies have tiny seeds. Their pods crack open when they are ripe. When the wind blows, the seeds shake out of the pod and are blown away.
|Floating Seeds: Did
our seeds float in the tub of water? What sources of water are there
outside where seeds might be
floating? During heavy rains, seeds are washed into ditches and float
until the water dries up and the
seeds grow where they are deposited.
Coconuts are sea travelers. The outside of a ripe coconut fruit is a waterproof coat made of fiber and air. The coat acts like a life preserver, allowing the coconut to float instead of sink. When coconut palm trees grow near the ocean, the coconuts may fall from the tree and roll in. The coconuts float until they are washed up on shore.
The lotus is a plant that grows in the water. It produces seeds in a flat head or pod. When the seeds are ripe, they fall into the water and float away until they find a good place to grow. Water lilies also grow in ponds and lakes. Their seeds float away in little cases of jelly. After a while, the jelly melts. The seeds fall to the bottom where they sprout and grow. Sometimes the seeds are eaten by fish. If these seeds are passed through the fish, they may be dropped far from the parent plant.
|Exploding Fruits: What
happened to our confetti when we ripped open the envelope or bag? It
exploded and fell all over the
ground. Have you seen purple violets growing in your yard or garden?
Did you plant them there? Violet seeds explode and scatter several feet
from the parent plant when
the violet fruit splits open.
The touch-me-not is a small plant that grows in woodlands. The pod that holds the seeds is made up of strap-like pieces that are hooked together. The straps are like springs that have been stretched as far as they can go. The slightest touch or bump makes the pod explode and sends the seeds sailing. This is why they are called “touch-me-nots.” Brightly colored garden impatiens also produce plump fruit that burst open when touched.
Witch hazel is a large shrub that has exploding seed pods. Birds love to eat the seeds and carry them away.
Teacher Note:Ask the students to take out a blank sheet of paper and fold it in half twice. Ask them about the four ways seeds travel. Have them write each of the ways at the top of the four boxes on their papers. Refer to the words written on the board. Have the students draw an example in each box. This activity should be put in their Growing in the Garden Journal folders.
APPLY(10 minutes, and take-home assignment)
How do people move seeds? Consider gardeners, farmers, and seeds salespeople and where/how they get seeds and where/how they plant seeds.
Have you moved any seeds? How did you do it? Where were they planted? What grew from the seeds?
Give some examples of good things that could happen from traveling seeds.
Give some examples of bad things that could happen from traveling seeds. What happens when lots of weeds grow in gardens or yards? Unwanted plants compete with our lawns, flowers, and vegetables for food, water, and air. What do people do with unwanted plants? It’s best to pull weeds before new seeds spread.
How do people travel from place to place? (Make a list on the board. Examples include walking, crawling, running, and biking. People also ride in cars, trucks, airplanes, on trains, bicycles, etc.)
Seed Collection:Give each student a manila folder to use for his/her seed collection. This is a takehome assignment. Instruct the students to find as many seeds as possible and glue them on the folder. Remind them that many of the foods we eat such as popcorn, rice, and beans are seeds. Many of the fresh fruits and vegetables we eat such as apples, strawberries, cucumbers, peppers, etc., have seeds in them. The students should organize their seed collections by the way the seeds are spread: air, water, wind, animals, people, or dropped from the plant. You may want to invite a Master Gardener, horticulturist, or agronomist to talk to the class on how to find seeds. Give the students two weeks to complete the project. Then have them share their collections with the rest of the class.
• Where did you find most of the seeds in your collection?
• Are the seeds the same color, size, and shape?
• How did most of the collected seeds travel?
• Did you have any surprises? Did you learn something new?
Burne, David.Eyewitness Books: Plant. N.Y.: Alfred A. Knopf, Inc., 1989. ISBN 0-394-82252-8.
Lauber, Patricia.Seeds Pop. Stick. Glide. N.Y.: Crown Publishers, Inc., 1981. ISBN 0-517-54165-3.