Plant Diversity

This week I want to start a series of articles spanning the next few months delving into the world of plants. I've written briefly about different species of plants, their uses, and some of their importance in a healthy ecosystem, but now I want to dive into the different structures, types, and functions found across them. Most people understand that trees, bushes, grasses, ferns, mosses, crops, and flowers are all considered plants. While many of these look vastly different from each other they share many common visible structures and internal mechanisms. This week I’m going to start with an overview of the variety of plant classes in the hopes of giving a basic intro.

Moss (Bryophyte)

Hornwort (Bryophyte)

First, let me provide a definition of a plant. Plants are embryophytes. The name comes from the way they protect and nurture the embryo inside the parent structure. This definition excludes algae and other things that may have been included with a less specific definition. Most plants are terrestrial (living on soil), but some species have evolved back into the water (such as water lilies and duckweed). All are complex, multicellular organisms. All plants are non-motile (they can’t move). Photosynthesis is their primary means of producing energy, but a small number are parasitic. Plants also display an alternation of generations between a haploid gametophyte (a multicellular generation with a single set of chromosomes) and a diploid sporophyte (two sets of chromosomes present).

Quillwort (Lycophyte)

Clubmoss (Lycophyte)

Plants can be further divided into two groups, those reproducing and spreading through spores: bryophytes (liverworts, mosses, and hornworts), lycophytes (clubmosses, spikemosses, and quillworts), and monilophytes (ferns and horsetails); and those reproducing and spreading through seeds: gymnosperms (conifers, cycads, gnetophytes and ginkgoes), and angiosperms (flowering plants). Plants can also be divided into those with vascular tissue (specialized tissue in the plant the transports water and nutrients around): lycophytes, monilophytes, gymnosperms, and angiosperms; and those without specialized vasculature: bryophytes. (Don’t worry about understanding the ins and outs of plant reproduction or tissue yet. I’ll make sure to cover them in detail in later posts.)

Fern Frond (Monilophyte)

Horsetail (Monilophyte)

Bryophytes include mosses, hornworts, and liverworts. They are grouped together based on their lack of vascular tissue, and are therefore referred to as non-vascular plants. However, they do not form a monophyletic group (a group made of an ancestor species and all its descendants). Instead they are more likely a paraphyletic group (a group made of an ancestor species and its descendants minus one or more monophyletic groups). In this case they are made of embryophytes minus the tracheophytes (plants containing vascular tissue). Bryophytes lack true leaves, stems, and roots. They are among the most primitive of land plants. They require almost constant moisture to keep from drying out as they lack many features that more advanced plants use to keep from drying out.

Lycophytes are represented by clubmosses, spikemosses, and quillworts. They still reproduce primarily through spores, but they have vascular tissue, and therefore; leaves, roots, and stems. They are more advanced than the bryophytes.

Monilophytes are made up of ferns and horsetails. They reproduce through spores, have vascular tissue, leaves, roots, and stems. They are the closest relatives to the seed plants.

Welwitschia 

(Gnetophyte, Gymnosperm)

Ginkgo (Gymnosperm)

Gymnosperms are composed of four different groups: conifers, cycads, gnetophytes and ginkgoes. Gymnosperms are more advanced than the previous groups because they produce seeds instead of spores for their primary reproduction. Gymnosperms are known as naked seed plants because their seeds are not enclosed. Even though they’re typically in cones for general protection, the seed itself is not encased. Conifers are made up of many common and important species including pines, firs, cedars, and junipers. They represent many of the largest plants on earth. Cycads generally have stout, woods trunks with a crown of leaves at the top. They can be confused with palm trees, but they are not closely related. Gnetophytes have some characteristics, such as vessel elements, not found in other gymnosperms. Ginkgoes are represented by one species of plant, Ginkgo biloba, and have been present on earth for millions of years virtually unchanged.

Quaking Aspen (Angiosperm)

Rose (Angiosperm)

Angiosperms make up everything else. They are the most common plants, representing some 250,000 species on earth. They have flowers, vasculature, stems, roots, leaves, and enclosed seeds. Orchids, maples, oaks, roses, apples, grasses, and many other common plants are all angiosperms. It’s important to keep in mind that not all flowers are showy and easily noticeable. When’s the last time you looked at a field of grass and pointed out its flowers? I assure you they are present, and when I get to the post on flowers I’ll cover it in much more detail.

Of course this is just the tip of the tree when it comes to all the fascinating aspects about plants. I realize that not many things are explained in detail here, but that’s not really the point for this post. The importance here is to understand the great diversity found in the world of plants. They started as very simple organisms, basically land versions of green algae. From there they evolved up to giant redwoods and flowering roses. There are many common characteristics, of course, but also a great deal of differences in them. Over the next few months I hope to introduce and explain features found in plants, and explain the differences. 

Our World Supplied by Trees

Taiga forest in Alaska. Taiga forests exist in northern 

latitudes and consist mainly of coniferous trees.

Look out the window and consider what you see outside. There’s a good chance a tree is on that list. Trees can be found almost anywhere. They cover huge tracts of land in areas ranging from the equator to arctic regions. How often do you stop and think of everything that trees provide? Take a guess at the number of products derived from one species of a tree or another. Would you say 100? 500? 1000? The actual number is nearer to 5000. That’s right. 5000 products rely on a product derived from a tree. Industries ranging from construction to health care rely on trees.

Peeling bark from a Pacific yew.

When I say health care relies on trees, I don’t mean wooden tongue depressors. Several drugs found their origins in chemicals produced by trees. Aspirin was first isolated from the bark of a willow tree. The cancer drug, Taxol, was found in the bark of the Pacific yew. Quinine, an antimalarial drug, is derived from the bark of the cinchona tree. Eucalyptus oil, used in many cold medicines, is extracted from the leaves of the eucalyptus. I could keep listing more drugs, but I think you get the idea. The amazing thing is this is just a fraction of the possibilities. There are still countless tree species that have yet to be studied for their medicinal properties.

Trees supply our paper. The list of products that use paper is astounding. Books, newspapers, posters, brochures, etc. are all produced from paper. Paper gave us the means before computers to spread information around the world and make it available to the masses. Cardboard is produced in much the same process and is just as useful. And regardless of whether you consider paper environmentally friendly, it does remain a completely renewable resource. Computers, however, are not renewable. Every computer is built out of materials that are finite. Think about that next time you’re trying to save the environment reading the news on your tablet instead of on newsprint.

A log being rough cut into lumber.

How many buildings could we build without a ready supply of wood? Not many. And they’d probably look a lot different. I realize that many large buildings are constructed from other base materials, but houses still rely a great deal on wood. Lumber cut straight out of the tree is used to frame the house. Added to the wood needed for framing is the collection of plywood, particleboard, fiberboard, I-joists, and glulam beams used in other parts of the construction. All of these are made from processed wood parts. Most of it is wood that would be unusable otherwise, and is processed with an adhesive to create these uniform products.

What about all the food we get from trees? I realize we don’t generally eat the wood itself, but trees produce many of our favorite foods. Apples, cherries, pears, oranges, and several other fruits grow on trees. Walnuts, pecans, almonds, and other nuts do as well. These crops represent an important portion of our diets and for those that grow them an important source of income.

Latex flowing out of tree bark into a collection vessel.

Rubber comes from the refined sap of a few species of trees, but the most common tree is the Pará rubber tree. Granted the majority of rubber doesn’t come from trees. Most of it is produced from petroleum. But rubber trees represent a renewable source of rubber. On the other hand removing natural habitat to grow these trees is not a viable option either. Rubber is used for car tires, without it what would we drive on? We use it to put soles on our shoes. Bouncy balls are made out of rubber, and who doesn’t love a bouncy ball?

A view of the Amazon Rainforest.

Obviously this is just a very small sampling of the vast number of products that come from trees. And while I’ve only listed a few I hope these stand out and show the importance of trees in our everyday lives. Without trees what would we have? Not much. Consider the importance of wood in just two items: lumber and paper. Where would our society be without these two things? Would we have advanced to this point without them? My guess is no.

I realize that many products have switched from wood to other materials. Sometimes this is because the other material is better for that use. Other times it’s because the other material is cheaper. But how often is that other product renewable? Unless it’s also a product that grows it’s probably not sustainable. I’m not saying to run out and start cutting down trees because they’re so awesome and can be used for many things. Improperly managed trees will not remain a renewable resource for long. But proper management and utilization of trees can allow us to keep using the plethora of items that are produced from them.

Come back next week for another post.

Josh

Fire: Bring on the Inferno

Imagine the forest and hills near Wenatchee 200 years ago, a stormy night in late August. The air is hot and stuffy. Dry lightning flashes in the night. A bolt shoots out and strikes the mountain. Flames appear. They spread. No rain to stop them. A wildfire is born.

With no controls this fire could burn for weeks or even months. Until the rain fell or it burned itself out. But this fire wasn't a raging wall razing the forest in its path. This fire burned through the brush and small trees. Clearing the forest floor, and occasionally burning tree stands. Just like it had 10 or 20 years before. Just like it would 10 or 20 years later. The cycle would keep repeating.

Except the cycle stopped. People showed up and they didn't like the fire. They feared for their lives and their livelihoods. Fire was evil. It had to be controlled. So they prepared for fires. They built fire lookouts. They watched the storms and rushed to extinguish any flames. They would control the fire.

For a time it worked. They stopped the fires. The forest grew. And grew. They harvested timber and the forest came back thicker than before. And they continued to stop the fires. But fire would not be denied. The forests were thick, but they were not teeming. Dead brush and branches littered the floor. Trees stood shoulder to shoulder where they had once stood apart.

Finally the trees grew too numerous. The underbrush too thick. Fire started and it raged. It burned. It devoured the landscape. The people had to fight so hard to contain it. And they did stop it.

But where the fire had gone nothing remained. Fires before had left tall, healthy trees relatively unscathed. Now there was nothing. The ground was dead. The trees were dead. Each trunk like a gravestone. The damage remains. It will be decades before these forests will be whole again.


Each new fire that crosses the land leaves a similar testament to our misunderstanding of the flames. A black wasteland. For years we assumed that fire was bad. How could something that burns the land be good for it? Fire is both destroyer and life giver. Fire often destroys what is there, but in return it allows new life to sprout from its ashes. The diversity of plants after a fire is astounding. There's no competition. The ground is open, free to whichever plant can get their seeds down first.

Several species require fire to propagate. Their seeds only released after a fire rushes over the landscape. Releasing their seeds from cones and other casings. Other species require fire to help them survive. Ponderosa pine grows best in open sunny locations. Its bark is thick and fire resistant, and its branches are far above the ground. It is suited to a landscape that receives fire. Without fire, other tree species can often out compete Ponderosa in its native habitat.

Fire should be embraced. Or at the very least accepted. Fire has always been here. Fire is much like a surgeon cutting out dead tissue and allowing new, healthy tissue to grow back in its place. The landscape is healthier with fire.

I'm not saying that fire should be allowed to burn and to just forget about the people. But there is a better line to walk. Strict fire suppression only leads to larger and more dangerous fires. Controlled burns are a good start. These can somewhat replicate a natural fire. It would be ideal to allow the fires to take back control, and burn what they've always burned. However, this isn't really a valid option anymore. The consequences are too severe.

Fire is not the enemy. Fire burns, but it also allows new growth. Growth that would never have occurred without a blank, blackened slate. Fire is as much a part of our landscape as the trees we are trying to protect. Accept it.