broccoli stalk, strawberry, and stalk of asparagus
Blog,  For Children

The Secret in Vegetable Stems: A Botany Lesson

Based on “Grocery Store Botany” by Joan Elma Rahn, a lovely children’s science book that is no longer in print.

Convincing your child or student to eat broccoli might be a little easier after they discover the botany secrets inside this favorite American vegetable. 

If you have already finished the chapter on “Secrets of Roots”, you will have most of the supplies already. The red food dye in water can be saved from roots and used again for this lesson. If you haven’t done the lesson on roots yet, save the dyed water for that observation. 

How to Teach the Botany Lesson about Stems

The supplies you will need are:

  1. Fresh broccoli
  2. Red food coloring
  3. Fresh asparagus
  4. Fresh strawberry
  5. Potatoes, organic is best for replanting portion of this study
  6. Opt: kohlrabi and broccolini
  7. Real cinnamon sticks
  8. Drinking glass or jar

Introduce the secret of stems

The next time you shop for groceries, be sure to buy some fresh broccoli, fresh asparagus, and strawberries for this experiment. A bonus, but an optional veggie to buy is kohlrabi and broccolini with lots of leaves. The bonus options will be mentioned in this study. 

Entice with cinnamon

Cinamon sticks are another way to peek your child’s interest in stems.One way that you can encourage them to complete this chapter is the promise of a cinnamon treat when they are finished, such as grating the cinnamon into some hot chocolate, or making snickerdoodle cookies with the grated cinnamon as one of the ingredients. Help them taste what cinnamon does to the recipe as a flavor. 

Broccoli and asparagus are the willing volunteer vegetables to share their secret


Broccoli is easily found in the produce section and is available year-round. Cut a  little bit off the bottom of the stem and look closely at the cut end. You should be able to see a ring that is actually veins. These veins are arranged differently than what you observed in the carrot. In the broccoli stem, the phloem and xylem are right next to each other. Let’s stain the xylem just like we did in the carrot so you can see them easier. 

Step one: Stain the broccoli stem

broccoli stem in dye
broccoli stem cut lengthwise showing dye in xylem

Mix red liquid food coloring in water. Make it a strong solution, about one tablespoon of dye to 3 or 4 tablespoons of water in a glass or jar. Place the cut end of the broccoli into the dye mixture. In a few hours, or overnight, you will see the red coloring in the top of the stalk. 

Remove the broccoli stem from the dye, rinse briefly, and cut a little bit off the bottom so you can have a fresh surface. 

Step Two: Observe, discuss and record your observations

Each vein will be red. The phloem will not be stained and will be green. 

Talk about it. 

  • Is it the same as the carrot?
  • How is it different?  

Botany Terms

Let’s pause and learn some botany terms so that you can have names for the “veins” you have discovered.

The phloem in on the outer side, toward the outside of the stem in the broccoli. The xylem is on the inside, toward the center of the stem. You can see this easier if you have a magnifying glass. 


The phloem are “tubes” that carry food and sugars that the leaves made to all other parts of the plant. Most of the flow is “downward”.


The xylem is a “vein” that brings water and nutrients upward from the root.

All parts of a plant are important

The phloem and xylem work together. The xylem has a specific purpose and the phloem has a specific purpose. Both transport important nutrients and fluids. The xylem brings us water and nutrients from the soil, the xylem transports food that the leaves make as a result of sunshine, water and the resulting nutrients that are made by the plant leaves. It’s quite complex, don’t you see? Yet, all parts work together in harmony to make a healthy plant that has food for us to eat. God is an amazing designer!

Step Two: Follow the xylem to the leaves

Turn the stem on its side and make a cut the long way up the stem, cutting through at least one of the leaves. You can see the vein all the way up the stem, showing how the stem sends fluids to its leaves. If you can see this, make another cut very close to the first cut and that should reveal a vein. If you still cannot see it, check to be sure the dye is at the top of the leaves. Sometimes, broccoli can be a little stale but most of the time, they still have the ability to move that dye up the stalk, so cut through a stalk that you can see the red at the top. 

Now, do you see the little stems and leaves at the top of the big stalk? Cut through some of those and follow the veins to the very top to the leaves. 

Step three: observe the length of the xylem

What? Those are broccoli leaves? Yes, they sure are shaped funny! But they are leaves. A broccoli plant also has other “normal” shaped leaves too. If you are really lucky, you can buy broccolini, which usually has those “other” kinds of leaves attached to them. 

Why not write and draw what you have observed so far?

Now that all this new, fresh information is swirling about in your minds, get it on paper before it fades away!

Be sure to subscribe so you can get the FREE student workbook chapter. Each chapter corresponds with the information given in this article and asks the questions given here. They are designed to integrate writing, art, and recording new words. You can hop over to the subscribe page here to find out more about all the bonuses you get. CLICK HERE


Asparagus has little leaves along the stalk. Carefully pull off these triangle leaves about half way up the stalk. You may discover tiny little branches with teeny little leaves under the triangle leaves that you pull off. Higher up the stalk, you can see branches with leaves that are large enough that they have small buds under their own leaves, kind of like a baby under another baby. 

Step One: Stain the Asparagus

Stain your asparagus the same way you stain broccoli. Cut a bit off the bottom, place it into the dye water, and let it sit for several hours or overnight. Cut the bottom off again and observe the xylem and phloem. 

asparagus stem

Talk about it. 

  • Is it the same as the broccoli? 
  • Is it the same as the carrot?
  • How is it different?  

Turn the stem on its side and make a cut the long way up the stem. Can you find the vein? See if it connects to the leaves. 

How does the plant know how to send water and nutrients to the leaves? God’s creation is amazing, even in broccoli and asparagus! 


If you have a kohlrabi, carefully break the leaves off the kohlrabi. You can see the leaf scars. Each leaf scar has dots. Those dots are where the veins were that (the kohlrabi) connects the stem to the leaves. 

The secret in strawberries

It’s truly debated among strawberry farmers: Strawberries are considered to be fruit, not stems! For the sake of this study, we are going to say that strawberries are swollen stems that are so delicious that they taste like fruit. 

According to the author, Joan Elma Rhan,”The strawberry flower grows on a tiny green stem that sticks up into the flower. The flower produces the real fruits of the strawberry plant.” 

You know how the tiny seeds can get stuck in your teeth when you eat a strawberry? Those little flecks on the strawberry are the true fruit while the stem is the part we call “strawberry”. A ripe berry is really a stem that has turned red. 

strawberry cut in half to show xylem

Step one: observe the inside of the strawberry

Cut a strawberry from top to bottom. Can you see little white veins that go to the little seeds you find on the outside of the strawberry? 

Cut another strawberry across the fruit/stem.

Talk about it and record your observations in your workbook.

  • Is it the same as the broccoli? 
  • Is it the same as the carrot?
  • Is it the same as the asparagus?
  • How is it different?  


Have you ever had cinnamon toast or cinnamon waffles? Have you had applesauce with cinnamon? Cinnamon is dried stem from a cinnamon tree! Cool, huh? If you have a stick of cinnamon, that may be easier to understand. But, if you have a jar of cinnamon in your spice cupboard, it may be hard to see that it was once a stem because it is the dried stem and ground into powder. If you can, buy some cinnamon sticks. I find them very inexpensively in the Hispanic section of the grocery store. Grate the stick on the finest side of a kitchen grater that you have. Now, use the grated cinnamon for flavor in snickerdoodles. You can mix it with sugar and sprinkle over buttered toast, waffles, or applesauce. Use it in pies, add to a smoothie. Stir cocoa or tea with a cinnamon stick. Some stems are sooooo versitile!

Reviewing: Veins in Plants

Think about how you have discovered the secrets inside of the stems of plants. Veins run through all parts of a flowering plant. Veins go from the root, through the stem, through leaves and into flowers, fruit, and seeds too.  Can you remember the scientific name for the veins that start in the root and go through the stem and the leaves? Can you remember the scientific name for the veins that carry fluid and nutrients from the leaves to the rest of the plant? Be sure to record what you learned in your workbook pages.

Potatoes have botany secrets too

A new secret: the potato

The potato grows underground. Did you know that? Don’t worry. Many adults do not know that this first-place favorite vegetable in America actually grows in the dirt. They just know that they love french fries and french fries come in a bag in the freezer section of the grocery store or in their lunch from the burger place! 

Potatoes are just as fascinating as the green stems we just explored. Now that you know they grow underground, maybe you concluded that they are roots. But, that’s not so! 

Potatoes are stems that have become thick. We call those thickened stems, “tubers”. Whoa! Stems grow underground? Yep. But, some people still say that they are swollen roots. Oh well. 

Observe a potato

Tubers have buds and leaves. The buds are called, “eyes”. Have you ever seen potatoes that have sprouted in your pantry? They are “eyes” that are trying to become a potato plant. The leaves of the tuber are very small and come off before they get to the grocery store. Actually, most come off as they are being harvested out of the dirt. If you look closely where the eye was, you can see a leaf scar. The eye makes a little indention. The leaf scar is right next to it, with a slight “u” shape. There are usually several eyes and leaf scars on a single potato.

I bet you didn’t know all that about potatoes! Now, you might want to become a gardener and grow some potatoes. I can tell you how.

Kids in the Garden: Growing Potatoes

Extra Experience: Sprout and grow more potatoes

For this portion of the Secrets of Stems experiences, please use an organic potato for the best possible results. Sweet potatoes work really well too. 

Prepare to plant potatoes

Be sure the potato is healthy. Choosing one with no spoilage is essential. Keep your potato in a dark pantry until you see growth coming from the eyes. Seeing the growth before you plant will assure you tht this potatoe has not be treated to prevent sprouting. If it’s organic, you won’t have to worry about that but it’s best to see sprouts first before planting anyway.

Plant Potatoes

Bury the potato “sideways” in soft, loamy soil, about six inches deep. For container gardens, use a container that is at least 36 inches wide and 12 inches deep with soil. Keep the soil moist but not soggy, allowing it to dry out somewhat between waterings, but never “bone dry”. After a couple of weeks, you should see stems and leaves come to the surface. 

The potato plant life

White or red potatoes will make “bush” type of stems and leaves, growing to over two feet in many cases. They may make beautiful blooms for you too. Wait until the stems and leaves turn yellow and die back before you harvest the potatoes found under the soil. This can take up to four or five months.

sweet potato vines in an outdoor pot

These vines are ready to transplant to another location. I have more barrels that I grow mine in.

Sprouted sweet potato in glass jar of water

Plant sweet potatoes to start new plants

Sweet potatoes make vines, rooting as they go. They will form potatoes outward from the original place they are planted. I’ve tried two ways of starting the vines, called, “slips”. Suspend them in water as shown. In four to six weeks, they should have new vines but it takes another 4 weeks to get long enough to plant. So I tried another way that I like much better.

Plant the whole potatoes the same way you plant white potatoes, taking care to plant them sideways, horizontally. You will see new vines within a couple of weeks. They will be ready to transfer to a new bed in another three or four weeks. Once they have those new vines, you can cut the vines from the origin when they are about eight to twelve inches long and place them in water. This will produce roots which can then be planted in dirt.

The sweet potato plant life

From there, you can set the vines in water but you could skip rooting them in water if you are diligent to keep the soil where you plant them moist for quite a few days. The way you do that is to cut the stem as described, place horizontally under two to three inches of loamy soil. That means much of the vine can be buried horizontally with only a few leaves showing at the end of the vine. Keep that soil moist but not soggy until it shows that it is healthy and growing again. The vines will continue to spread so be sure to plant in an area where they can roam. Wait until frost or the plant begins to die back before harvesting your potatoes. 

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You did it! You taught a botany lesson! For most teachers and homeschool classes, this lesson can take several days to complete when you add the workbook pages that integrates art, writing, and learning new botany words.

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May all your weeds be wildflowers!


A photo of the author, Deborah Schreffler

“But seek first the kingdom of God and his righteousness, and all these things will be provided for you.Mat 6:33 CSB


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