Last fall, I completed the third edition of my book, Kingdoms of Life Connected: A Teachers’ Guide to the Tree of Life. This came only six years after the second edition, which in turn came eight years after the first edition. “Why all this change?” you may ask.
I found that updates were needed because of changes in biologists’ view of the diversity of life. The data about how organisms are related continue to pour in, and because of this, the details of lineages and relationships change. You may be tempted to wait until the field stabilizes and stick with older ideas. Children, however, need a useful view of the diversity of life, even if it will be somewhat amended later. They cannot build on a foundation that is clearly obsolete. Specifically, it is no longer useful to present children with Five or Six Kingdoms, and those charts need to go in your history-of-science file.
I updated Kingdoms of Life Connected from cover to cover. I redid the lists of learning resources – books and websites; I purged links that no longer worked and added new ones. Publishers and authors have brought forth valuable new books in recent years, and I added titles to the lists while retaining older but useful books. I revised all the text, including the activities and lesson suggestions. I fact-checked the information to make sure it was as up to date as I could make it.
There is one especially important addition, a new lesson for introducing to the Tree of Life chart to beginning elementary children. This lesson gives older children important concepts as well, particularly if they have not yet had this overview. The introductory lesson leads children to the idea that all life shared a common ancestor and is connected. It shows them the relationships between the major branches of life. For example, they learn that the animals and fungi are sister lineages and that plants are only distantly related to fungi.
I’ll give a brief summary of some of the changes below. For more information, see the book, which is available at https://big-picture-science.myshopify.com/collections/biology/products/kingdoms-of-life-connected-third-edition (printed version). The ebook (pdf) is at https://big-picture-science.myshopify.com/collections/biology/products/kingdoms-of-life-connected-third-edition-ebook.
There are no big changes in the prokaryotes. I have kept a very basic approach because it takes extensive knowledge of biochemistry to understand the many branches of bacteria and archaea. Introductory college biology texts present a few basic lineages, and I felt that this approach would be good for children as well.
In the protists, I rearranged the Excavata lineage on the Tree of Life chart. Now, the euglenazoa and kinetoplastids are sister lineages and the metamonads are the first branch. I expect that Excavata will be split apart and redone in the future. It probably won’t be a eukaryotic supergroup, but studies continue to confirm the other supergroups – Archaeplastida, SAR, and Amorphea.
Scientific terminology evolves, and I was happy to see a complicated name go away. The branch of the stramenopiles and alveolates was previously called Chromalveolata, but that term has fallen out of favor. It originally described a lineage that included two branches I didn’t show, the cryptophytes and haptophytes; these are now placed elsewhere on the Tree of Life. The branch of the stramenopiles and alveolates may get a new name, but it seems best to leave that branch blank for now.
The fungi were the major branch that changed the most. The former Zygomycota lineage is now divided into two main lineages, the Mucoromycota and the Zoopagomycota. On my Tree of Life chart, I show the larger one, Murcoromycota. Its branches include the pin molds or Mucoromycotina (black bread mold, for example) and the arbuscular mycorrhiza fungi or Glomeromycotina (AM fungi). The AM fungi were previously placed on their own branch, but they have been added back to Mucoromycota. I didn’t add the Zoopagomycota to the Tree of Life chart, but if you have children who are interested in learning more, Fungarium by Katie Scott and Ester Gaya, is a good book for launching their explorations.
In the animal kingdom, studies have clarified some relationships in the protostome branch. You can give children the term “Spiralia” for the lineage previously called Lophotrochozoa. The whole branch is called Spiralia; “Lophotrochozoa” still refers to the mollusks and annelids. It is another of the situations where it is useful to know an older and newer term. “Lophotrochozoa” has been used for the Spiralia branch for about 20 years, and it appears in a number of websites. I recommend looking to the future and using “Spiralia” primarily. It is certainly easier to say and spell.
In the plant kingdom, studies have resolved several questions about the bryophytes. They are a single branch of life, a monophyletic lineage. The first branch was recently determined to be the hornworts. The mosses and liverworts are sister lineages. The older story was that the liverworts were the first branch because they do not have stomata. It appears that their ancestors lost their stomata rather than never having them.
The virus chapter now has suggestions for making a model of a coronavirus. I published this chapter as a stand-alone pdf in 2020. Note that if you have the third edition of Kingdoms of Life Connected, you already have the content of “What Is a Virus?”.
It is easy to become overwhelmed by all the names and branches of life. I recommend that you concentrate on the larger branches on the Tree of Life and continue to other branches as children (and you) learn about these and are interested in pursuing more. For in-depth studies at the elementary level, I recommend the digging further into the animal and plant kingdoms.
Start with the big overview of the Tree of Life. After that, my learning material, Sorting Branches on the Tree of Life: Vertebrates and Plants, is a good place to go. It is available as a pdf that you can print https://big-picture-science.myshopify.com/collections/biology/products/sorting-branches-on-the-tree-of-life-vertebrates-and-plants or as a printed material https://big-picture-science.myshopify.com/collections/biology/products/copy-of-sorting-branches-on-the-tree-of-life-vertebrates-and-plants-file-for-printing.
Enjoy your explorations of the Tree of Life!
The nesting boxes for the plant kingdom are a classic Montessori material. (They are usually called Chinese boxes, but I don’t like to use that term. They certainly didn’t come from China.) Like many other materials that were created many years ago, this one needs a make-over or at least a reality check to see if it reflects what children will see in their later studies.
Paraphrasing a Chinese proverb, if your nesting/Chinese boxes are based on a two-kingdom classification, and they contain the bacteria and fungi, the best time to change them was before 1980. The second best time is now.
The point of elementary studies isn’t to teach children names and ideas that they are not likely to see again. Maria Montessori said that children who complete her elementary program would have acquired knowledge equal to a high school student of her day. She wasn’t trying to create a separate set of biology terms; she was giving children the mainstream academic knowledge of her day. Continuing to use the terminology and concepts of the traditional lessons without checking to see current academic view leads to problems. Children may have to discard their Montessori lessons and go back to the beginning to learn contemporary biology. “Unlearning” is very hard for people. They tend to cling to the first way they learned something, and they must accept that their version is wrong before they can accept another view.
If there were nesting boxes that reflect the current academic view of the plant kingdom, how would they look? Here are my ideas.
Picture a large, green box that is labeled “Plant Kingdom.” It could have other labels as well as that main one. Possibilities are the more formal Latin Kingdom Plantae, or the more descriptive one, Embryophytes. The latter is the informal scientific name for land plants.
We take the lid off this box and find a small box labeled “Bryophytes, the nonvascular plants” and a much larger one labeled “Tracheophytes, the vascular plants.” Inside the bryophyte box, there are three smaller boxes labeled “hornworts”, “liverworts”, and “mosses.” Should there be a label for the division/phylum of these boxes? There doesn’t have to be. I have an advanced botany textbook that doesn’t use a Linnaean rank name for these branches of plant life. If you want to add the division/phylum names, see Wikipedia. It is generally quite good for plant classification.
The larger Tracheophyte box contains two boxes, a small one labeled “lycophytes” and a much larger one labeled “euphyllophytes, the true-leaf plants.” The lycophyte box has three small boxes inside, the club mosses, spike mosses, and quillworts. Alternatively, the lycophyte box could list these three lineages on the lid and not separate them. They are best described as orders of the lycophytes.
The euphyllophyte box has two boxes inside, a smaller one labeled “fern clade, the monilophytes” and a larger one labeled “Spermatophytes, the seed plants.” The fern clade box has several smaller boxes. They are labeled: “ophioglossids – whiskferns, alder’s tongue ferns, and grape ferns”; “equisetums – the horsetails and scouring rushes”; and “leptosporangiate ferns or polypod ferns – the true ferns.” If your school is in a tropical climate, you may need to add a fourth box for the marattid ferns. They are huge plants that grow only in the tropics.
The spermatophyte box holds two boxes, the angiosperms or flowering plants, and the gymnosperms, the naked seed plants. The gymnosperm box holds four boxes – the cycads, the ginkgo, the conifers, and the gnetophytes. It is uncertain at present whether the gnetophytes belong in their own separate box or within another of the seed plant boxes. It is clear that they do not belong in the angiosperm box, however.
The angiosperms or flowering plants must have a big box. They make up about 90% of the plant kingdom. There are several boxes inside their box. A couple of very small boxes hold the first branches – the water lilies and the anise tree. Then there is a small box labeled “magnoliids,” a medium box labeled “monocots,” and a large box labeled “eudicots.” Three-quarters of the flowering plants are eudicots; about 22% are monocots.
All this can be imagined, but it will take quite some creativity to make physical containers that can actually hold an image and information about each of these branches of the plant kingdom. The information should include the lineages of the plant. For example: Sunflower lineages – embryophytes, tracheophytes, euphyllophytes, spermatophytes, angiosperms, eudicots. The text should also give some of the defining features – the derived traits – of each group.
If you need the illustrations or more information, see https://big-picture-science.myshopify.com/collections/montessori-botany-materials/products/the-plant-kingdom. This is a pdf of a PowerPoint for teacher education. You can print the images for use in your classroom. It has all the images you need except quillworts. Those lycophytes are rare, and the main reason to include them is that they are the closest relatives to the ancient Lepidodendron trees.
Please let me know if you need help or have questions on plant kingdom nesting boxes. If you want to have another set for the flowering plants, that’s a more involved story. It would be fun to do, however.
Happy plant explorations,
Priscilla
In January, I visited Tucson, Arizona and enjoyed exploring the Sonoran Desert. The plants there show many adaptations to the heat and dryness. The cacti and palo verde trees are what I expected. What surprised me is that plants I thought would need much more moisture are also able to survive in that climate.
There had been rain before my visit, enough that several hiking trails were impassable because normally dry creeks were flowing. As usual, if you want life, just add water. The plants that need moisture to reproduce, the spore-bearing plants, came out of hiding and were thriving. I saw a number of different ferns, but those weren’t a big surprise. I had seen ferns growing from cracks in lava flows before. The key for ferns seems to be finding a moisture-conserving crack on the shady side of a rock outcrop.
The spike mosses, genus Selaginella, were fluffed out and green. One of their common names is resurrection plant, so you can image how they look when they are dry. Spike mosses are not true mosses. They are members of the club moss lineage aka the lycophytes. One Sonoran species, Selaginella rupicola, is called rock-loving spike moss. There were hillsides with many spike mosses protruding from cracks between rocks.
The mosses were looking very green and active. They are known for their ability to dry out and wait for water. They formed their green carpets out on more open ground and in sheltered rock overhangs. It was in one of the latter habitats that I found the big surprise. There were liverworts growing with the mosses.
Liverworts are the plants that have leaf pores that are always open. I think of liverworts as growing in habitats that have abundant moisture, not just isolated periods of wet weather. It is true that the liverworts in Oregon’s Willamette Valley survive the summer drought, but the humidity is never as low nor the temperatures as high as in the Sonoran Desert. The Sonoran liverworts are small, thalloid ones, much smaller than the ones native to western Oregon. They have the right appearance for a liverwort. They look like a flat leaf growing right on the ground, and they branch into two equal parts, which gives them a “Y” shape. They must have special adaptations and be very tough and resilient to live the desert.
Plants offer surprises in all habitats, not just the desert. You just have to take the time to look.
