Category: Plant Science (Page 8 of 9)

Seed to Seed: Where We Go Next

September 1, 2015 / Roberta / 3 Comments

After 257 Mystery Seed of the Week posts, it seemed like it was time for a change. But what to do next?

The answer was inspired by a book, Seed to Seed: The Secret Life of Plants by Nicholas Harberd.

Seed to Seed is the journal of plant geneticist Nicholas Harberd from the year 2004. In it, he records his personal observations and discoveries. Because of his prominence in the field, in many ways it is also the story of the uncovering of the genetic control of plant growth.

Right in the first entry in the book, Harberd reveals that over the last few decades plant scientists have decided on a unifying method to help move the field of plant genetics forward more quickly. Instead of trying to examine a little of the genetics and development of many, many different plants, perhaps it would be more enlightening for everyone to study one plant thoroughly and assume that the other plants probably had the same or similar properties.

The plant they chose to investigate was thale-cress, Arabidopsis thaliana.

(Public domain illustration ofÂ Arabidopsis thaliana by Johann Georg Sturm from Wikimedia)

Why did they select this small weedy plant? Arabidopsis thaliana is the lab rat of the plant world. It is small and it self-pollinates, so it can be grown easily in the lab. It completes its life cycle quickly, producing flowers within approximately three weeks and seeds in about six weeks. In addition, thale-cress has a small genome that has been completely sequenced, so geneticists can build on what is already known.

Where does this unifying idea take us?

Rather than moving randomly from plant species to plant species as we have been doing with Seed of the Week up to now, let’s change gears.Â Following in Nicholas Harberd’s footsteps, let’s learn more about plant science by delving deeply into the secrets of a single type of plant over the next few months. Who knows what we might find out!

What do you think of this plan? Would you like to join in the journey? What questions about plants would you like to answer?

Zinnias: Flower Cycles and Parts

April 2, 2015 / Roberta / 5 Comments

If you have been following Growing With Science, you know that we have been closely observing the insects on a small planting of zinnias for the last few weeks (posts about zinnia insects 1, 2, and 3).

The variety of zinnias we have been observing are ProfusionÂ® Fire, which are hybrids between regular zinnias (Zinnia elegans), and the Mexican or narrowleaf zinnias (Zinnia angustifolia).

While initially observing the insects on the plants, we also noticed something about the plants themselves, specifically the flowers. Do you notice anything about the flowers in the photograph above?

As it turns out, the flowers change as they become older.

The zinnia flower head starts out as a tightly closed bud.

When the flower head first opens, it is deep, bright orange, almost scarlet.

As the flower head matures, it becomes a medium orange. Do you see any other changes?

The oldest flower heads have faded to almost yellow. They look a bit worse for wear.

There have been some changes to the flowers within the flower head as well, but we need to learn some vocabulary before we can investigate it.

Flower Parts

(â€œMature flower diagramâ€ by Mariana Ruiz LadyofHats. Public Domain image at Wikimedia Commons.)

You may have seen a diagram like this one describing the various parts of a hypothetical flower. Basically, the ovary, style and stigma form the female part of the flower that receives the pollen. The stamens, made up of filaments and anthers, are the male parts of the flower that produce pollen.

Very few flowers actually conform to this simple diagram, and the zinnias are certainly much more complex. Rather than a single flower, what we see is actually a cluster of minute flowers called disk and ray florets.

You may have to scroll back up to the bigger photographs above to see the parts clearly, but in the young flower head the ray florets around the outside are flowering, which is evident by the yellow stigmas. Only a few disk florets in the center have begun to open.

In the middle-aged flower head, most of the ray florets have finished flowering and many of the disk florets around the outside have begun to flower.

In the older flower heads, the outer florets have finished flowering and are developing the all-important seeds. Only the disk florets at the very center are still flowering.

Flower Part Dissection Activity for Children

Note: check whether the children have severe pollen allergies before starting this activity.

Gather:

Living flowers of different types (see flower notes)
Safety scissors and other dissecting equipment (age appropriate)
Diagrams/illustrations of flower part with labels
Dissecting microscope (optional)
Paper (optional)
Pens or markers (optional)
Tape (optional)

Flower notes:Â Tiger lilies or other lilies are excellent examples of simple flowers as seen in the diagram. Daisies and sunflowers are good examples of the complex flowers. Working with a large group? You might want to ask your local grocery store or florist if they would be willing to donate flowers that have passed their freshness date. Keep the flowers alive in a vase of water.

Have the children observe the different types of flowers closely. Provide diagrams or illustrations naming the flower parts. Once everyone has had a chance to observe the flowers, allow the children to dissect the flowers to examine the parts more fully. Very young children can simply pull them apart. Older children might use safety scissors. Still older children can use dissecting pins and a dissecting microscope, if available.

Remove the petals or pull off the ray florets. Can you find the stigma? What about the stamens? Is the stamen releasing pollen? What color is the pollen? What is inside a disk floret?

Older children might want to spread the parts onto a piece of paper or card stock and tape them down. Label the parts.

Extension:Â If the flower parts aren’t damaged too badly, allow the children resemble the parts to make their own mix of “Franken-flowers.”

Resources:
The Clover & the Bee; A Book of Pollination by Anne Ophelia Dowden

This image does not do this beautiful book justice. It includes many highly-detailed, scientifically-accurate diagrams of different types of flowers with their parts labelled. It also discusses pollinators and how they use differently-shaped flowers in different ways. Super scientific reference for educators and older children.

Age Range: 10 and up
Hardcover: 90 pages
Publisher: HarperCollins; 1st edition (May 1, 1990)
ISBN-10: 0690046774
ISBN-13: 978-0690046779

This is an older book by the same author which covers similar material.

Publisher: Ty Crowell Co (June 1963)
Language: English
ISBN-10: 0690506562
ISBN-13: 978-0690506563

Disclosure:Â I am an affiliate for Amazon. If you click through the linked titles or ads and make a purchase, I will receive a small commission at no extra charge to you. Proceeds will be used to maintain this self-hosted blog.

Seed of the Week: Popcorn Science

February 28, 2012 / Roberta / 1 Comment

As several people recognized, our mystery seeds from last week were indeed popcorn.

(Photograph of popcorn on cobs from Wikimedia)

The scientific name for popcorn is Zea mays L. subspecies mays, according to the USDA plant name database. On the Internet, you may find it as the synonym Zea mays var. or subspecies everta. You will also encounter the names Zea mays var. everata or yet another synonym, Zea mays var. praecox. Although it is confusing, the bottom line is that popcorn is a type of corn.

(Photograph of Corn by PetrÂ Kratochvil)

Popcorn grows on stalks like the ones shown above. The male, pollen-producing flowers or tassels are on the top and the female “ears” below. The silk of the ears capture the pollen grains, which is when pollination occurs. The seeds develop within the husks of the ears, on the cob. When the plant turns brown and dry, the popcorn is harvested.

Science Activities With Popcorn

Did you know popcorn is a perfect tool for science exploration with kids? Even though we think of popcorn as a fun snack, you can carry out serious science experiments with it.

1. Compare the germination of beans and popcorn (dicot plants versus monocot plants).

Gather:

Dry bean seeds, especially big types like lima beans, available in the in the grocery store in the dried food area. (Be aware that seeds intended for gardening may be treated with chemicals.)
Popcorn, preferable on the cob (sometimes available in the grocery store as well)
Paper towels
Water
Plastic sandwich bag, paper plate covered with plastic wrap, or plastic cup with plastic wrap to cover, one per participant

First, have the children explore the seeds and compare the popcorn with the beans. How do the different seeds look? What color are they? What shape are the different types? Do they smell? Are the seeds hard or soft? Do they seem to have an outer covering? Have older children open some seeds and look at them under a microscope. If appropriate, encourage the children to write down their findings.

Wet paper towels until damp, not dripping wet. Note: you will need to keep the paper towels wet throughout the experiment. Try to avoid handling too much, as the paper may begin to grow mold. You may add soil to the center of the cups, but again that increases the chance for mold growth.

For plates or plastic bags:

Lay the paper towels flat. Place bean seeds and popcorn seeds inside the towel. Fold the top over, creating a sandwich with the seeds inside. Slip the paper towels into a plastic bag and close, or onto a paper plate and cover with plastic wrap.

For the plastic cups:

Press the paper towels into the cups and against the sides. Slip the seeds between the towel and side, so the children can see them. Cover with plastic wrap to prevent drying.

Depending on the temperature, the beans should start to swell and a root start to form as early as 24 to 48 hours later. Show the child how to slip open the two halves of the bean, called the cotyledons (the food storage part of the seed – they are the dark purplish structures surrounding the leaves in the photo below) and observe the newly emerging plant inside. The popcorn may take up to a week to germinate. Compare the bean seeds, which have two cotyledons to the popcorn seeds, which have only one cotyledon (monocot). Why might seeds take different lengths of time to germinate?

Open a few every day to see how the new plant grows. Allow the children to experiment with the seeds. They might want to remove portions of the plant or seed or change the growing conditions (moisture, light, add soil) to see what happens.

2. The Science of Popcorn:Â Â The Pop!

Check out this video of a kernel of corn popping:

Ever wonder how a small, hard kernel could become fluffy white popcorn? Let’s find out more.

Requires adult supervision.

Gather:

at least 1 cup of popcorn kernels (not popped)
three bowls,
a hot air popcorn popper (or other method for popping corn)
a cookie sheet
a measuring cup
water and access to a sink or another large bowl
a colander
paper towel
easily removable tape, such as painter’s tape
a pencil or pen, and paper to record your results
access to an oven
timer or clock
oven mitts

Preheat the oven to 200Â° F. Label the bowls with tape.

Bowl 1 – wet
Bowl 2 – dry
Bowl 3 – control

Start by placing 1/3 cup of the popcorn kernels in bowl 1. Add one cup of water and then set aside for one hour.

Spread 1/3 cup popcorn kernels on a cookie sheet and place in the oven for one hour. Check periodically to make sure they are not burning.

Pop 1/3 cup popcorn kernels and catch the results in bowl 3 (control).

After an hour, drain bowl 1 by dumping the contents into the colander (over a sink) and dry the bowl and kernels with a paper towel. Pop it in the same manner as you did for the control. Catch the results in bowl 1.

Using oven mitts, remove the cookie sheet from the oven. Have any kernels popped? Now pop the dried kernels and catch the results in bowl 2 (dry).

Measure the amount of popped corn in each bowl using the measuring cup. Count the number of kernels that did not pop. Look at the texture and size of the kernels.

In general, the more moisture the kernels contained, the more steam they produce and the better they should have popped. Can you have too much water? Try leaving 1/3 cup of popcorn in water overnight. How does this affect the kernelsâ€™ ability to pop?

You can expand this experiment by comparing different brands of popcorn.

Hope you have fun. Please let us know if you have any questions. We would also love to hear what you find out.

Other places to find out more:

A group called Naked Scientists have some great videos and more information about Popcorn Steam Explosions.

Popcorn.org has an extensive Popcorn Lessons, complete with a free poster to download.

	Popcorn (Charlesbridge)by Elaine Landau and Brian Lies, with illustrations by E. Landau
	The Popcorn Book by Tomie dePaola
	Corn by Gail Gibbons
	An adult nonfiction title: Popped Culture: A Social History of Popcorn in America by Andrew F. Smith
	Sources of seed at Amazon: 100 Strawberry Popcorn Seeds for Planting in the Small Garden
	Cutie Pops Popcorn – 100 Seeds – Multicolored Miniature