Monthly Archives: June 2014
Tryon Creek’s Strangest Plant
By Bruce Rottink, Volunteer Nature Guide and retired Research Forester
When you think “plants” you probably envision your favorite wildflower, your favorite shade tree, or maybe even your favorite vegetable! Different kinds of flowers, different shapes and sizes, but it’s almost a dead certainty that all of them are green, ‘cuz that’s what plants are, green! They contain a green pigment called chlorophyll that allows them to make their own food from sunlight, water and carbon dioxide.
Call me a weirdo, but my favorite plant is not green. It’s one of Tryon Creek State Natural Area’s most rare and unusual plants, Indianpipe (Monotropa uniflora).
In contrast to the normal, green Pacific waterleaf (Hydrophyllum tenuipes) plants in the picture below, the Indianpipe is white!
What’s going on with this plant? How does it make its food without the green chlorophyll?
Truth be told, Indianpipe, also known as ghost plant, is a slacker. It doesn’t make its own food! Scientists (who love big words) call it a “myco-heterotroph.” The “myco” refers to fungus, and the “heterotroph” means the Indianpipe gets its food from other organisms. Underground, something really interesting is going on. In order to survive, the roots of the Indianpipe need to connect with the underground mycelium (which look like long very thin hairs) of a fungus. AND, that fungus needs to have other mycelia attached to the roots of a tree. The fungus typically has a mycorrhizal relationship with the tree. That means that the fungus provides the tree with certain minerals the fungus has absorbed from the soil. In turn, the tree supplies sugars to the fungus.
Here’s where it gets tricky.
After the fungus has absorbed some sugar from the tree, the Indianpipe, which is also attached to the fungal mycelium, steals some of that sugar from the fungus. But in this case, the Indianpipe doesn’t provide any benefit to the fungus.
So some of the sugar produced by the hardworking tree is taken by the fungus, and then some of that sugar is stolen by the Indianpipe.
Right now is a great time to start looking for Indianpipes.
At Tryon Creek, I’ve seen Indianpipes emerging as early as May 29, but June and July seem to be the big months. At first you will just see a little white upside-down “U” shape emerging from the ground, as illustrated below. This one is only about 2 centimeters (3/4”) above ground.
In this example, the stem is on the right, and the flower head is on the left, in the upside-down, or “nodding” position. You can also see the tiny, nearly translucent leaves.
Hey, wait a minute!
If the Indianpipe doesn’t make its own sugar, it doesn’t need any sunlight. So why does it bother to pop up above ground every year?
Well, anytime an organism does something that doesn’t seem to make much sense, you can bet it has something to do with sex! And that’s the case here. The flower of the Indianpipe needs to get up above ground to shed its pollen and so that the female parts of the flower can be pollinated by other Indianpipes to produce seed for the next generation. Here some of the tiny leaves have already withered and turned black. The stem will continue to push up, and at first the flower will remain closed, as seen below.
As the stem grows, the Indianpipe plant gets taller, and taller. It tops out about 15 to 20 centimeters tall (about 6 to 8 inches).
The flower starts out life pointing down; as the stem grows taller, the flower gradually lifts up and points straight up to the sky.
And as the flower matures, you can see the anthers which produce the pollen. The pollen in the flower head is the only thing about the plant that has a normal color, yellow, although it is pretty pale!
After the pollination and seed production is complete, the soft stem soon starts to disintegrate, and falls to the forest floor. The cycle is complete, now cross your fingers for next year’s sighting of the ghost in the forest.
If you’re lucky enough to see one of Tryon Creek’s Indianpipe plants, please be respectful of these rare and delicate plants. Indianpipe, perhaps better than any other plant at Tryon Creek teaches us an important lesson; namely that there many different ways to be a success. It’s a lesson we can apply in our own lives too!
The Rocky Road to Reproduction
By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester
Ah, spring! A time when plants at Tryon Creek State Natural Area are in bloom, with the promise of new generations of plants to come. Or not! While beautiful flowers are a vital step to a new generation of plants, it’s a rocky road to reproduction. If we follow through the process of plant reproduction, we see that the obstacles are numerous. Failure to reproduce is such a common result that every living plant at Tryon Creek is something of a miracle.
But let’s start at the beginning.
Each plant must first initiate a flower. For many species, for example, Douglas-fir (Pseudotsuga menziesii) and trillium (Trillium ovatum), this takes place the summer before the flowers appear. Each year a significant percentage of individual plants never form a flower. This is often the case if, for example, a plant is growing in a shady location, which just barely meets the needs of plant survival.
Perhaps the plant had an abundant crop of flowers the year before, and the plant’s reserves were drained in that effort.
Perhaps the weather conditions last year were not very good for initiating flowers.
Below is a picture showing a trillium that just did not produce a flower this year. Every year at Tryon Creek SNA, there are LOTS of trilliums that don’t produce a flower.
So they won’t be reproducing!
But let’s suppose a flower is initiated. That’s a nice start, but there’s still a long way to go. This spring I noticed several of Tryon Creek’s low Oregon grape (Mahonia nervosa) that had produced a flower stalk and flowers (an inflorescence), but it never actually opened up to show flowers. It dried up and died before it got to that point.
The picture below is of a low Oregon grape inflorescence that started to develop, and then for some reason, died.
But even if the plant has produced an inflorescence and it’s opened up to expose the flowers, many hazards still await. The weather can turn deadly. A late frost or an extra-dry spring can mean the end for flowers that have already emerged. And that’s not all, the picture below shows some bigleaf maple (Acer macrophyllum) flowers laying on the Old Main Trail that got blown out of a tree by a spring windstorm!
Well, they’re never going to produce seeds.
So suppose a flower has developed, opened and escaped the usual weather-related problems. That’s a good start, but that’s not the end of the story. In trilliums, like most other plants, seeds are produced only when pollen (produced by the male parts) lands on the stigma (the sticky female part of the flower) to fertilize the ova (egg). In trilliums, as in many plants, the male and female parts are found in the same flower.
Trilliums, like lots of other plants, can’t be fertilized by pollen from themselves, they need pollen from a different plant.
Here’s the bad news:
So much pollen is produced by each flower that scientists believe sometimes the flower’s own pollen completely covers the female stigma blocking pollen from other plants. Last year I did a survey of 88 trilliums at Tryon Creek State Natural Area along a portion of two trails. Of 88 trilliums that had produced flowers, only 33 produced any seeds! That’s just 37-1/2% of the flowers that produced seeds! Now before you get alarmed, this is about the same percentage of success that scientists have reported for trilliums in other areas. At this time of year, you can see the fat green seed pods on the successful plants (photo on the left), and the tiny brown dried up seed pods (photo on the right) of the flowers that failed.
Whew! What a struggle it’s been so far! But there’s still a couple more hurdles to go.
So suppose you’re a plant that’s managed to produce some seeds. Seeds are little packets stuffed full of high energy starches or fats that help young plants get a good start in life. Oh-oh! Turns out there are lots of critters at Tryon Creek that are interested in packets of high energy (the “seeds”!)
Can you guess who?
Douglas squirrels, spotted towhees, mice, and more! We can see the tragic (for the seeds!) end results in every squirrel midden where a squirrel has chewed apart a Douglas-fir cone and eaten all the seeds.
In the picture below, you can see the central axis (“stalk”) of the cone in the upper left part of the picture, surrounded by the pile of cone scales.
Oh no! They were so close to success.
Fortunately, there is a bright side.
Every year there actually are some seeds that survive the whole gauntlet. These seeds fall to the ground and germinate early in the spring, producing new plants.
Here is a close-up of one new maple germinant:
And some more hope for seeds
Here is a picture of a whole cluster of brand new bigleaf maple seedlings ready to grow up and become the queens of the forest.
There are more than 40 new trees started.
The photo below, taken just 4 weeks later, shows that all the new seedlings have been wiped out! Maybe the weather got too dry, maybe the soil was a little too hard for the roots to penetrate, or maybe a hungry mouse stopped by.
Whatever the reason, it’s the end of the road for those little maples!
It’s a rocky road to reproduction, but once in a great while a plant makes it all the way, like this majestic Douglas-fir near Old Main Trail in the photo below.
When you understand all the barriers to successful plant reproduction, it’s a lot easier to think of each and every plant as a miracle! The next time you’re at Tryon Creek, take a good look at all the plants around you! These are the survivors, the ones that were both lucky and tough!