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In a previous post, we have discussed the Classification of Organisms. Now might be a good time to learn about some of the common plant families.

Learning the characteristics of common plant families can make identification of specific plants easier, plus gives us a sense of how plants are related. Most of us recognize the most common crop plants grown in fields and gardens, so let's start with those.

Important Note:  You would think plant names would be stay the same once they were created, but it turns out that with advances in genetics and efforts to add consistency, many of the names are changing. Keep in mind that all these names could change next week.

  1. The Carrot Family - Apiaceae

This family used to be called the Umbelliferae. They are still characterized by having flat, clustered flowers called "umbels."

Examples of this family include:

carrot-flower-2carrots (this is a carrot flower)

cilantro-flower-bestcilantro,

queen-annes-lace-beautifuland Queen Anne's lace. Can you see the similarities in these flowers?

2. The Sunflower Family - Asteraceae

This large plant family used to be called the Compositae. What appear to be single flowers are actually a "composite" or collection of tiny disk and/or ray flowers.

Examples of the sunflower family include:

sunflower-singlesunflowers,

lettuce-flowerlettuce,

artichoke-flowerand artichoke, as well as many ornamental flowers,

mix-of-zinnias-87like these zinnias.

3. The Bean Family -Fabaceae

Many common food plants belong to this family, including beans, peas, carob, lentils, mesquite, etc. The seeds are contained in pods. The flowers are complex.

Examples:

pea-plantpeas,

tepary-bean-flowertepary beans, and

blackeyedpea-bloom3black-eyed pea.

4. The Mint Family - Lamiaceae

The members of this family include many common herbs. Most have square (four-sided) stems and many have similar tubular flowers.

mint-flower -spear-81

This flower structure is from a spearmint plant.

 

mexican-oregano-flower

These are the tubular flowers of Mexican oregano.

5. The Lily Family - Liliaceae

The plants of this family are known to have special swollen structures for storing food, such as bulbs or corms.

Examples include:

green-onion-bulbonions (the bulb),

onion-flowersonion (the flower)

 

garlic-chive-flowergarlic chives, etc.

rain-lilyOrnamental lilies also belong to this family.

6. The Grass Family- Poaceae

Grasses are unique plants because they grow from the base instead of the tips. Many crops are members of this family including rice, corn, wheat and barley.

corn-plantcorn-kernels-318Corn

wheat-in-pot-firstwheat-seeds-goodWheat

lemongrass-going-to-flower-65

Grass flowers consist of spikelets.

7. The Rose Family - Rosaceae

The flowers of members of the rose family typically have five petals and five sepals. Many of the different types of fruit we eat come from plants that belong to the rose family.

Examples include:

blackberry-flower-1blackberries,

good-apple-flowerand apples, as well as pears, peaches and even strawberries.

8. The Nightshade Family - Solanaceae

Our final plant family contains crops such as potatoes, tomatoes, peppers and eggplants. The flower petals are often fused together rather than separate.

tomatoes-blossoms-flowerstomato flowers (public domain image)

sonoran-nightshade-with-leaves-66nightshade flowers

 

Plant Family Quiz
(Answers below)

dill-flower-101

A. To which plant family does dill belong based on its flower structure?

plant-family-testB. How about this type of sage?

swallowtail-on-flowerC. Any ideas what plant family these yellow flowers belong to?

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Want to learn more? Feel free to leave questions in the comments.


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Plant-Science-Lessons

To see our complete plant science lessons, either visit the plant science category (newest posts to oldest posts) or the plant science section of our experiment archive page (links to posts in order).

Looking for books about plants for children? Be sure to visit our growing list of gardening and plant science books for kids, as well as our list of children’s books about seeds.

For more activities, try our Gardening/Plant Science for Kids Pinterest board.

Quiz Answers

  • a. Dill belongs to the carrot family, Apiaceae
  • b. Sage belongs to the mint family, Lamiaceae
  • c. The yellow flowers belong to the sunflower family, Asteraceae

Plants have chemicals in their leaves that can convert sunlight, water, and carbon dioxide to food in the form of sugars. The process is called photosynthesis. The chemicals in the leaves that absorb light are pigments. The most common pigments that convert sunlight energy are green pigments called chlorophyll. Other pigments found in leaves include xanthophylls, carotenes, and anthocyanins (see below for definitions).

Chromatography Activity

How do scientists study the colors in plants? One way is to perform a simple color separation or “chromatography.”  Let's look for the pigments found in growing plant leaves, in this case fresh spinach which is full of pigments.

The chromatography requires time, at least an hour, so prepare your children in advance. It also requires rubbing alcohol.  Read and follow the warnings on the alcohol bottle label carefully.

You will need:

  • A fresh spinach leaf per child
  • Small clean containers, like a yogurt cups or jars, one per child
  • Tool to chop the spinach leaves (requires adult supervision)
  • Rubbing alcohol
  • Stirring utensil that will fit in containers
  • Coffee filter cut into about ¾-inch-wide strips that will fit into the container from top to bottom, one per container

Chop up the spinach leaves into tiny pieces. Put the chopped bits into the bottom of the containers. They should cover the bottom in a layer, up to ¼-inch deep. Pour in just enough rubbing alcohol to cover the leaf bits. Stir briefly. Slide the coffee filter strip into the container, so that the bottom touches the alcohol/leaf mixture. Rest it against the side. Now wait for about an hour.

The alcohol should slowly move up dry part of the coffee filter, carrying the pigments as it goes. The heavier pigments will travel more slowly, the lightest most quickly. Once the wet alcohol "front" nears the top of the strip of coffee filter, remove it. Check the colors. Lay it on a piece of paper towel or paper and let it dry a bit. Often the colors of the pigments will show more intensely once the alcohol has evaporated.

Your coffee filter might look like this:

spinach-chromatography

The green bands at the bottom are chlorophyll pigments. The plant uses chlorophyll to convert the sun’s energy into food. If you look closely, there are two bands of green, with some yellow. Those are the two chlorophyll pigments, named chlorophyll a, and chlorophyll b. Chlorophyll a is the main type of chlorophyll. Chlorophyll b is an accessory pigment that captures light energy from a broader range of light and transfers it to chlorophyll a.

Just above the green is an intense yellow band. The yellow is a group of pigments called xanthophylls. Xanthophylls are what make corn yellow. When chickens eat plants with xanthophylls, they can use it in their eggs to make the yolk a deeper yellow.

At the very top, is a thin orange band. Those pigments are carotenes, named for the first plant tissue they were isolated from, carrot roots.  Carotenes are also found in pumpkins and squash. Carotenes are also used for photosynthesis.

Now compare the colors in the growing spinach leaf to those of the autumn leaf. What colors are the same? What colors are missing in the leaves? What colors are in the leaves but not in the spinach?

autumn-leaves-chromatography094

Autumn leaves lose the green pigments first. The two types of chlorophyll actually break down as the leaves begin senescence. Does the plant make the the orange and yellow carotenes and xanthophylls in response to losing the chlorophyll? No, those pigments have been there all along in the growing leaf, but masked by the deeper green chlorophyll. When the green disappears, we can see the other pigments.

Another color, however, wasn’t present before. The intense red pigments found in some autumn leaves are called anthocyanins, and are known for making flowers, and vegetables like beets, red or purple. It turns out that certain trees make a lot of anthocyanins in their leaves in the fall. Leaves don't produce it earlier in the year.

Right now scientists don’t know for sure why certain types of trees produce the anthocyanins. One suggestion is that the anthocyanins act like sunscreen to help protect the leaves while the last bits of nutrients are being moved out and down to the roots for storage over the winter. Another suggestion is that red trees are less visible to insects. Harmful insects may lay their eggs on trees in the winter, and may choose trees that are yellow over those that are red.

Related:

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Want to learn more? Feel free to leave questions in the comments.


leaf-border

Plant-Science-Lessons

To see our complete plant science lessons, either visit the plant science category (newest posts to oldest posts) or the plant science section of our experiment archive page (links to posts in order).

Looking for books about plants for children? Be sure to visit our growing list of gardening and plant science books for kids, as well as our list of children’s books about seeds.

For more activities, try our Gardening/Plant Science for Kids Pinterest board.

Up to now we've been looking at the exterior of plants. It is time to delve more deeply inside.

What do you see when you look closely at a leaf?

parallel-leaf-veinsTake this oleander leaf, for example. You can see that is is green, but there are also lighter yellow or white areas. The light line down the middle is called the midrib. It is the main vein of the leaf for moving water and nutrients in and out. The midrib often also adds stiffness or structure to the leaf.

Perpendicular to the midrib are numerous smaller veins. In the oleander leaf they are lined up parallel to each other. The smallest veins form a netlike pattern.

leaf-veins-passion-vineThe veins in this passion vine plant are more complex because some come to a V and others are curved.

The leaves of certain plants will have some features not found in all plants. For example, the yellow bumps on the leaves above are specialized glands called nectaries. In this case they occur outside of flowers, so they are also called "extrafloral nectaries."

oil-glands-citrus-leafThe bright specks in this lemon leaf are glands filled with citrus oils. The spots are sometimes called "pellucid dots" because they light up when the sun shines through the leaf.

Other plants may have numerous hairs or trichomes.

leaf net veinsIf we were able to go closer into the leaf, we might see something like this leaf cross section diagram:

Leaf_anatomy(Public domain image from Wikimedia)

Leaves are made up of different types of cells.  On the right of the illustration is a cluster of xylem (carry water) and phloem (carry food) cells labeled as the vascular bundle. Those are the elements of the veins.

The two types of cells labeled "mesophyll," the palisade and spongy,  are the cells that contain the chloroplasts and are responsible for the majority of photosynthesis that occurs in the plant. We will discuss photosynthesis extensively in a future post.

At the bottom is found an opening called a stoma (plural stomata), which is where gases go in and out of the leaf. Because the openings also allow some water to be lost, under certain conditions the cells around the stomata, the guard cells, swell up and close the opening.

Plant_cell_structure(public domain image of a generalized plant cell from Wikimedia)

If we could delve yet deeper, we could see the make up of individual plant cells. Plant cells have some features in common with those of other organisms, such as the presence of a nucleus, endoplasmic reticulum, and mitochondria. Other features are only found in plants, such as the cell wall made up of cellulose.

Check out this interactive plant cell model to learn more.

Activity Suggestion 1. Look closely into plants

Gather:

  • Fresh plant material (non-allergenic and non-toxic)
  • Dissecting microscope or hand lens
  • Age-appropriate cutting implements, dissecting pins

Examine the plant material under a microscope or hand lens. Dissect stems and leaves into sections to see structures more clearly. Draw and label what you see.

Activity Suggestion 2. Make a model plant cell.

Making 2D and 3D models of plant cells out of a variety of materials has become a classic science activity for middle school/high school students. There are numerous examples online. Start at this Model Plant Cell Pinterest page for ideas, as well as the diagram above and the interactive website.

Activity 3:  Water use by plants

We all know we must water our houseplants, lawns, and gardens, but what are plants doing with the water? Primarily, the plants have chemicals in their leaves that can use sunlight, water, and carbon dioxide to make food in the form of sugars. This is called photosynthesis. Plants also use water to move nutrients, to add support to their structures, and to keep cool. All that water moves from the roots through the stems to the leaves via the xylem.

Gather:

  • Clear plastic bag big enough to hold a few leaves
  • Twist-tie or chenille
  • Tree or shrub (with leaves close enough to the ground to put a bag over)

On a warm sunny day, slip a clear plastic bag over some leaves on the end of a branch of a tree. Tie the bag tightly to the branch with the twist-tie or chenille, trapping the leaves inside and preventing air from escaping. Visit the tree in fifteen minutes and then again in a half hour. What is happening inside the bag?

plant-transpiration

You should see the bag start to fill with condensing water. Why?

Trees release a lot of water on a hot day through a process known as transpiration. Much of the water comes out of the stomata. You are capturing the water that is being released. which condenses when it reaches the plastic. Some figures suggest that more water enters the air from plants transpiring than from evaporation from the surface of the ocean.

Transpiration cools the plant on a hot day and is also involved in helping the plant move water to the chloroplasts.

How to make this activity an experiment:

  • compare the rate of transpiration at different times of the day or at different temperatures (by measuring the amount of water produced in a given time)
  • compare transpiration rates between different trees and shrubs

Related:

Enchanted Learning has a collection of leaf anatomy activities, including a diagram of a cross-section of a leaf to label.

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Want to learn more? Feel free to leave questions in the comments.


leaf-border

Plant-Science-Lessons

To see our complete plant science lessons, either visit the plant science category (newest posts to oldest posts) or the plant science section of our experiment archive page (links to posts in order).

Looking for books about plants for children? Be sure to visit our growing list of gardening and plant science books for kids, as well as our list of children’s books about seeds.

For more activities, try our Gardening/Plant Science for Kids Pinterest board.