Category Archives: Tryon Creek
By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester
At the most basic level, the universe is orderly, although sometimes that order is not immediately apparent. Albert Einstein famously remarked, “God does not play dice with the universe.” Fortunately, in the forests of Tryon Creek State Natural Area (TCSNA) we have many wonderful examples of the orderliness of the universe. For this article I will focus on the symmetry that we see in so many of the organisms in the forest.
The most common types of symmetry we can see at TCSNA are typically referred to as spherical, radial and bilateral symmetry. Another way to think about these kinds of symmetry is symmetry around a point, symmetry around a line and symmetry around a plane.
Spherical Symmetry (Symmetry around a point)
With spherical symmetry, there is one point in the middle of an object, and no matter which direction you go from that point, everything is the same. If you’ve already guessed that all the examples are spheres, you’re right! The seeds and fruits of some plants are the best examples of this at TCSNA. For example, the picture below shows the fruit of a bedstraw (a.k.a. “cleaver”) plant (Gallium spp.) The scar in the middle of the picture is where the fruit was attached to the stem.
Other forms of symmetry get a little more interesting.
Radial Symmetry (Symmetry around a line)
A second type of symmetry is radial, where there is a central axis to the object, and the parts all stick out equally in any direction from that central axis. One of the best examples can be seen in this mushroom fruiting body. Imagine the red dashed line going down the center of the stem of the mushroom. At a given distance from the ground, if you travel out at any 90° angle to that red line the mushroom structure is identical.
The picture below is of the underside of the mushroom’s cap. I’ve put in a red dot to indicate the central axis of the fruiting body. No matter which direction you look out from the center, the structure looks essentially the same. The edges of the gills that you see as lines, all point to the center of the mushroom.
Looking at the underside of the mushroom’s cap provides an additional perspective on radial symmetry.
The mushroom above is an example of the simplest kind of radial symmetry. But radial symmetry can be more complicated, and more interesting.
Spirals – A special case of radial symmetry
The mushroom pictured above is a very simple example of radial symmetry, but more complex examples can be easily found at TCSNA. The most obvious are some of our native conifers. For example, at first glance the scales on a Douglas-fir (Pseudotsuga menziesii) cone might appear to be arranged in a random pattern.
In fact, the scales on a Douglas-fir cone are arranged in a definite spiral pattern around a central stalk. The scales are actually arranged in multiple spiral patterns. To illustrate this I painted the bracts (the three-pointed papery structure attached to each cone scale) to highlight these spirals. Each spiral is a different color. The results can be seen in the movie below. Since each cone scale is actually part of three different spiral patterns, I have painted three different cones, each illustrating one of the three patterns. A different color of paint was used to mark each of the spirals. Watch first one cone and then the others to see these three different spiral patterns.
You can see in the movie that there are a set of three spirals of cone scales going in one direction around the cone axis at a very gradual angle. There is a second set of five spirals going around the cone at a steeper angle in the opposite direction. Finally, there is a third set of eight very steep spirals going about the cone in the same direction as the first set of spirals. So each scale is part of all three spirals going around the cone’s central axis.
In any given plant, the number of spirals are a part of a set of numbers known as the Fibonacci sequence of numbers. The Fibonacci numbers were described by an Italian mathematician more than 800 years ago (and Indian mathematicians had apparently described them even before that). Starting with the number 1, each subsequent number is the sum of the two previous numbers. Below is the start of the original Fibonacci sequence (the “modern” version starts with zero, which has no impact on the rest of the sequence):
1, 1, 2, 3, 5, 8, 13, 21, 34, etc, etc, ad infinitum.
In the botanical literature, it is traditionally reported that the number of spirals in any plant are always two consecutive numbers of the Fibonacci sequence. With one exception. The pineapple fruit is almost always described as having three spirals. I present here the possibility that the Douglas-fir cone, like the pineapple, is composed of three spirals, not the traditionally recognized two. But, whether it’s two spirals or three, it represents an example of order in nature.
Bilateral Symmetry (Symmetry around a plane)
Finally, there is bilateral symmetry, which is symmetry with respect to a plane (think of a sheet of glass). The structure is identical on both sides of the plane. The butterfly below is a beautiful example of bilateral symmetry. Think of an imaginary sheet of glass running vertically through the butterfly’s body. Each side of the body is an identical mirror image of the other side. The easiest feature to see in the photo below are the patterns on the wings.
Plants often exhibit bilateral symmetry, as exemplified by the bigleaf maple (Acer macrophyllum) fruit shown below. In fact there are two different planes of symmetry. The first one is centered around the red line drawn on the picture. The second plane of symmetry is represented by the paper on which this picture could be printed. The front and back sides of the seed are identical.
But wait… Not everything in the forest is symmetrical!
My favorite example of a non-symmetric organism in the forest is the banana slug (Ariolimax columbianus). Below are two pictures of the same slug. One picture is of the right side of the forward part of its body, and the other is of the left side of the forward part of its body. As you can see, the slug only has one breathing hole, and it is on the right side of its body. Thus, the slug does not display symmetry in this regard, it is asymmetrical. Every slug has its breathing hole on the right hand side of the body.
But that’s not the only way a slug is asymmetrical! Look at the coloration on the body of the slug pictured below. A black spot on one side of the slug is not matched with an equal sized, or shaped black spot on the other side of its body.
Symmetry is often useful, such as birds having one wing on each side of its body. Imagine a bird trying to fly with both wings on the same side of its body. But In truth, while nature has intended many things to be symmetrical, oftentimes the symmetry is not perfect. These imperfections may result from mutations during development, or accidents. So what you ask? Scientists have discovered that some animals, like female peahens and barn swallows, prefer males with symmetrical tails. To the birds, symmetry could be proof of a potential mate’s normalcy, which is often the safe choice.
The symmetrical patterns that we see in much of the flora and fauna of TCSNA provide some reassurance in the orderliness of the universe. It suggests that perhaps Einstein was correct!
By Bruce Rottink, Volunteer Nature Guide & Retired Research Forester
Some strange things live in the forest at Tryon Creek State Natural Area (TCSNA) but for my money, none is stranger than the organisms known as slime molds. Taxonomists, folks who specialize in classifying organisms, haven’t all agreed on how to classify slime molds. They do, however, all agree that slime molds are clearly neither plants, animals, fungi nor bacteria. Slime molds are fascinating creatures because they have a very strange life cycle, and a highly unusual “body”. This note focuses only on the plasmodial slime molds, which are the type you will probably see at TCSNA. [Important: The slime mold names used in this note represent my best efforts at identifying these creatures, based on their strong similarity to photos on the internet.]
Where do slime molds grow?
The best place to find slime molds at TCSNA is on rotting wood. Old logs, tree stumps, or dead standing trees are prime candidates. This is because the primary foods for slime molds are bacteria and fungi. These are abundant in dead wood. Experts say the best times to find these slime molds is either spring or fall, when the forest is fairly damp. The slime molds pictured in this note were found at TCSNA in April, July, September and November.
What’s so weird about slime molds?
The weirdest thing about slime molds is their dramatic changes in shape over the course of their life cycle. Let’s start with the point in the life cycle which gives these organisms their name. The most active adult stage of the slime mold is when it looks like (surprise, surprise) slime! This nearly formless stage is called the plasmodial stage. At the risk of being indelicate, the adult slime mold in this stage looks like someone with serious nasal congestion blew their nose onto a log. This stage looks a little “blob-y” and has a distinct “wet” appearance. The plasmodium stage of life is the diploid stage where the slime mold has chromosomes from both parents, just like you. The example pictured below was on a decaying tree trunk that was lying on the ground near the West Horse Loop Trail.
These blobs of life are unusual in that they are giant cells with many thousands of nuclei in each cell. For most life forms, one nucleus per cell is the rule. Also, at this stage, there is a thin cell membrane, but no rigid cell wall. The big advantage to having giant wall free cells is that these plasmodia can move by streaming the cell contents (cytoplasm) from one end of the plasmodium to the other end. The plasmodium will move in the direction that the streaming cytoplasm is heading. Laboratory studies have observed slime molds moving at approximately 1 inch per day towards concentrations of food.
When food starts to become scarce, the slime mold moves into the next stage of life. This stage is called a sporangium. The sporangium, as you might guess, is the stage that produces the spores. The forms of the sporangium differ greatly, depending on the species of slime mold.
How does the sporangium develop?
There are many different sizes, shapes and colors of sporangia, depending on the species of slime mold. Examples I’ve found at TCSNA are included below.
The series of photos below shows the development of a single sporangium found on a standing dead tree along the Trillium Trail is shown. Unfortunately, I found the sporangium when it was completely developed. This was formed by a plasmodial mass similar to the one pictured above. A tough shell develops to protect the developing spores on the inside. This sporangium is the species of slime mold called “false puffball”. Its scientific name is Enteridium lycoperdon. The most striking thing about this sporangium is that in my entire life I have never seen a natural object that has looked so much like plastic. Measured vertically along the trunk of the tree, it is about 3 inches long.
Just one day later, the surface of the sporangium has started to crack apart. The interior of the sporangium is filled with small brown spores. This particular sporangium was growing very close to the trail. I suspect the yellowish area which is oozing just a little yellow fluid is in fact a wound inflicted by a curious visitor to the park!
After three additional days, the surface of the sporangium is starting to seriously deteriorate, exposing even more brown spores.
In just an additional 3 days, the surface of the sporangium is almost completely gone, and many of the spores have been washed or blown away. Now the spores will germinate and produce single celled amoeba-like cells that crawl around. These cells are the functional equivalent of human egg and sperm cells. These amoeba-like cells will find and fuse with a compatible amoeba-like cell. Then this fused cell will grow to become a new plasmodium, restarting the cycle.
The photo below gives you an idea of what the interior of this slime mold sporangia contains.
While observing the above slime mold, I noticed some insects on its surface. As I approached quite close to take photos, the insects boldly maintained their positions. I sent this picture to Josh Vlach, an entomologist with the Oregon Department of Agriculture. He indicated this insect “looks like a Mycetophilidae possibly a species of Mycetophila”. Mycetophilidae is a family of insects, while the Mycetophila is a genus within that family. The common name for this group of insects is “fungus gnats.” This type of insects oftentimes lay their eggs in either mushrooms or slime molds. The developing larvae eat the mushroom or slime mold. One of these insects appears in the picture below.
Are there other kinds of slime mold at TCSNA?
Yes, I’ve spotted several other kinds of slime molds at Tryon Creek. Below is an example of a slime mold in an advanced stage of spore production. It was on the side of a downed log just off the Old Main Trail. The cluster of spore producing bodies seem to be resting on a thin sheet of shiny material that looks like dried slug slime. The entire cluster is 9 inches horizontally, and 6-1/2 inches vertically. The thickness of these spore clusters is less than 1 inch. When touched, they easily broke into a dark brown powder. These appear to be the species Tubifera ferruginosa, the red raspberry slime mold. In a younger stage, which I clearly missed, they are bright red.
In the close-up below, you can see more detail of the structure of this slime mold.
Next is the dog vomit slime mold. (I don’t name ‘em, I just report ‘em!) For once, you might like the Latin name better – Fuligo septica. Below is the sporangium of this colorful slime mold, which I found on a fallen log next to the Middle Creek Trail. The outer covering of the sporangium is just starting to break apart, revealing the brown spore bearing parts of the slime mold. On the moss just below the sporangium, you can see a few remnants of plasmodial strands that didn’t quite make it into the sporangium.
Below is a close-up of the surface of the dog vomit slime mold. It is substantially different in both color and texture from the first slime mold pictured in this note.
Slime molds are an amazingly diverse group of organisms, and the next species testifies to that. The photo below appears to be a slime mold in the genus Trichia. The plasmodium, the white slimy part, and the sporangia, the orange balls on a stalk, coexist. The orange blobs bear the spores for this slime mold.
Not only are the sporangia of this species dramatically different in appearance, they also differ in size. The next photo compares the sporangia to my thumbnail.
So what’s the lesson here?
The slime molds really are the weirdos of the forest, and trust me, this note only scratches the surface of that weirdness. They remind us that there are many ways to be successful. The slime molds eat the bacteria, and the larvae of the gnat fly eat the slime molds, and many things eat the gnat files. Every creature in creation is linked together, and we would be wise to remember that.
Weather and Climate: Looking Back and Ahead
By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester
Talk about a double whammy! The Portland area, including Tryon Creek State Natural Area (TCSNA), has set an all-time record for December rainfall, and the 2015 United Nations Climate Change Conference has just wrapped up in Paris! Lots of people are thinking about the weather and climate now!
The growth, survival and distribution of the plants at Tryon Creek State Natural Area (TCSNA) are affected by a host of factors. These factors include climate and weather, but also things like soil chemistry, soil depth, the steepness of the slope the plant is growing on, and soil moisture holding capacity. Probably the two most important weather variables are temperature and rain fall. Most of the discussion around climate change has to do with increases in the mean annual temperatures. This is a good place to start, but perhaps inadequate to explain all the changes we might see.
So how might climate change effect our forest?
Climate change might affect TCSNA in many ways, for example, altering the species composition of the forest. I am in my third year of monitoring the growth and development of a variety of plants in my phenology study at TCSNA. In my monitoring I visit the same plants every week to ten days and record their status. Perhaps looking at some of the results might provide a peek into the future. One of the species that I am monitoring is Pacific waterleaf (Hydrophyllum tenuipes). As the waterleaf tends to form dense clumps, I am monitoring approximately a 3-foot diameter circle of plants at each of four separate areas, rather than just trying to track a single stalk.
Pacific waterleaf is a perennial plant, which sends new shoots up every year from rhizomes. Think of rhizomes as “underground stems”. The above ground shoots die back in the “off season” and only the roots and rhizomes persist from year to year. At TCSNA waterleaf is generally from 40 to 60 cm (16 – 24”) tall at maturity. These shoots die back sometime in the summer, generally after they have produced a crop of seeds.
Reviewing the phenological records, the last two years have seen a lot of variability in the behavior of the Pacific waterleaf at TCSNA. The chart below indicates the presence or absence of waterleaf leaves at each of the four monitoring sites on a weekly basis.
Weekly Presence/Absence of Pacific Waterleaf at Four Locations at TCSNA over Two Years
Key: Yellow = Waterleaf Absent; Green = Waterleaf Present;
Week 1 = first week in January, Week 26 = end of June, Week 52 = last week of December
The late-winter through early-summer growth is the time when the waterleaf is making the vast majority of its sugar to support the plant, AND when the plant is producing seeds. The second emergence of leaves is around weeks 40 to 45 (roughly October thru early November). This “second leafing out” produces leaves that tend to be fairly small and I’ve never seen this second leafing produce flowers, much less seeds. And, as you notice, there is a certain amount of “now you see it, now you don’t” with this second leafing out. In at least some cases, the second leafing out leaves are eliminated by a serious frost.
It is interesting to note that on the Middle Creek Trail, there is never a “second leafing out.” The major difference between the Middle Creek waterleaf patch, and all the others is that the Middle Creek patch is on a significant slope, and is more exposed to direct sunlight. All the other patches are on flatter sites. Thus, it may dry out sooner than the other patches, and not have the late-season water it needs for a second set of leaves.
Why are these years so different?
- One thing that you can see immediately is that the green bar (indicating the presence of waterleaf plants) consistently ends earlier in 2015 than in 2014 for any given site. In 2015 the leaves disappeared on average 7 weeks earlier than in in 2014. This is a significant amount of time.
- The seeds of the waterleaf mature approximately in mid-June, so in both cases the plants survived long enough to produce seeds, and nothing more. It is likely that the leaves which persist after seed production are producing sugars to help support the plant for the next growing season.
What could have caused that difference?
The contrasts in weather between 2014 and 2015 are dramatic. I think the weather data probably goes a long way in explaining this year-to-year behavioral difference.
First let’s look at the (Portland) air temperatures maximum and minimum for the years. In each chart, the highest average minimum or maximum air temperature is highlighted in color. Where the temperature for any month was more than 5° F higher than any other year, it is highlighted in red.
Average Daily Minimum Air Temperature – Portland
(In °F; higher year highlighted red)
You can easily see that for most of the spring and early summer months, the minimum temperatures were higher in 2015 than in 2014. But that’s just the start. The next chart tells us even more.
Average Daily Maximum Air Temperature – Portland
(In °F; higher year highlighted in red)
Again, for most of the spring and early summer months, the average maximum daily temperature was higher to dramatically higher in 2015 than in 2014. The yellow-highlighted months are more than 5°F warmer than the comparable month in 2014. The average high temperature in June 2015 was almost 10° F higher than June 2014! This higher temperature would probably cause the plants to lose more water, produce less sugar, and grow less in 2015 than they did in 2014. But the icing on the cake is yet to come. Just take a look at spring/summer rainfall data (from the PCC Sylvania rain gauge station).
February through June Rainfall
Wow! The early growing season rainfall in 2014 was nearly twice what it was in the comparable time in 2015.
The “growing season” for Pacific Waterleaf in 2015 was both hotter and drier than it was in 2014. The result was that the above ground waterleaf shoots disappeared on average 7 weeks earlier. Yikes! A seven-week difference in leaf persistence is not trivial.
I can’t wait to see what kind of impact this has on waterleaf in the 2016 season.
Think of all the linkages that there may be between waterleaf and the other organisms in the forest. Possibly less food for waterleaf-eating insects, less cover for mice scurrying around looking for food, fewer waterleaf seeds for food, and possibly increased soil erosion from late summer rainstorms.
This is the story of just one species of plant, but it might foretell the challenges we face if climate change continues unabated.