Trees/ Tree Biology


9/18/2010: Now I know you’re probably thinking “Now there’s a barn burner of a subject!” and you might be right. But its barn burning that inspires this blog so to speak. You see I live in the foothills of the Coast Range of Oregon in an area that was once part of the Great Tillamook Burn, a series of huge devastating forest fires in the 1930’s. It inspired the a great reforestation effort by government and thousands of citizen volunteers to replant the charred land left behind. I live in the forest that resulted from that effort but the threat of forest fire is a concern every summer. Every summer I vow to put a sprinkler system on the roof of my barn and every summer I never seem to get to it. This summer I actually got to doing a takeoff of what I needed and when I discovered how big and expensive a pump system I would need to deliver the volume of water and the height required to the top of my barn . . . well it was easy to put it off again.

I got to thinking - how do trees do this? They don’t need a thousand dollar pump and they can raise hundreds of gallons of water a day as much as 300 feet in the case of the redwood. How they do it is an amazing and true tree tale (well , I think it is and I’m writing this blog)! Here’s how they do it.

There are really three “pumps” or hydraulic processes a tree, or for that matter any vascular (having a stem) plant, uses to transport water. The first starts in the roots. It’s called osmosis and it’s the principle that water will move from areas of higher concentration to lower concentration to seek equilibrium. Maybe you remember this from high school physics class. I do because it was a day I was actually in physics class and not someplace else, like detention hall. There was this fish tank filled with water (and without the fish) and separating the middle of it was a semi-permeable membrane. It allowed water to pass through but not solutes (dissolved particles). Mr Yarashefsky, our physics teacher, then dumped salt in one half the fish tank and, in a period of time (which I can’t recall because my lab partner, Hawk Rafferty and I were talking about how it might be more fun if we were in detention right now), the membrane began to bulge toward the non-salt half of the tank. Mr Y proceeded to point out that water molecules were moving to the salt side because the salt particles took up the places of water molecules meaning lower concentrations of water there and causing water to move from the higher water concentration (non-salt) side to lower water concentration (salt) side. And that’s what tree roots do. They can raise their solute levels, dissolved stuff like sugars and minerals, in their root sap to cause water to move from the soil water into the roots and it even causes a pressure that exerts a pushing force of sap (water and minerals) up the stem.

Stay with me now. I promise its get more exciting than detention.

The second “pump” is capillary action. It’s not so much a pump as a lubricator. Inside the stem of the plants are hundreds of tiny connected pipes called xylem that carry the sap up the stem. Think of them like straws. In these small capillary tubes, water both climbs the wall of the tubes better and it pulls up water behind it because water has great cohesive properties (which is why when you spill a glass of water on the floor it beads up rather than spreading evenly out all over) . The smaller the tube, the better the capillary action. To illustrate the point, try this experiment at home. Fill a glass with water, stick a straw in it and suck water through it. No problem. Now get a 4” diameter fire hose and try to suck water through it. Big problem, no capillary action

The third “pump” is transpiration. Trees lose water through their leaves and sometimes stems. There are little “ports” called stomata, hundreds of them on a leaf. When they’re open they release water vapor and oxygen and take in carbon dioxide, gasses essential to photosynthesis and respiration. It’s that water vapor loss that pulls water up behind it in the xylem. Again like sucking on a straw. And it’s a lot of water! One mature oak was measured as transpiring 525 gallons of water in a day. That’s like a 4 person hot tub’s worth of water

So you’ve got osmosis pushing from the roots and transpiration pulling from the top and capillary action making it easier for both of them. Imagine how big and expensive a pump and piping system you would need to pump 500+ gallons up a 300 foot redwood and you can begin to appreciate the genius of the natural hydraulic architecture of a tree. That’s amazing and true.

I’d like to dedicate this blog entry to Mr. Yarashefsky, whom I’m sure is retired now, but if he should ever read this I want him to know . . . that I’m not a blockhead! and when I wasn’t in detention I did learn something! . . . I... I just maybe didn’t show it at the time.


This is the true, amazing, and somewhat seamy story of a local tree victim. In New Jersey, it’s garbage and the Mafiosa; in Japan, its protection and the Yakuza; and in the Pacific Northwest, its the cascara tree and bark bandits. Cascara (Rhamnus purshiana) is a small native tree in the forest understory or shady clearings. Its prominently veined leaves, beautiful golden fall color, and interesting mottled reddish brown bark make it a most appealing landscape tree, which is greatly underutilized and underappreciated. Alas, what it is appreciated for is as a . . . laxative.

The purgatory powers of the cascara were long known by the native Americans. In the Chinook trade jargon (a patois of English and Salish used for trading purposes) it was known as the Chittum bark. Spanish priests in California gave it its present, and less blunt, name, Cascara sagrada , or “sacred bark” As a laxative, cascara cannot be taken fresh as it is so strong it will cause vomiting and bleeding, but its effects are made much milder by aging the peeled bark for a year. Once the bark has been peeled from the tree, its dead and that’s been the problem between cascara and the “plugged-up” populace since it was first introduced to western pharmacology in 1877. Since its introduction to medicine, overharvesting has led to the demise of mature cascara throughout its range (SW Britsh Columbia south to NW California), so that by the 1960’s it was so scarce that substitute laxative materials had to be developed. Cascara, however, has continued to be a major ingredient in commercial laxatives until 2002, when the FDA issued a ban on its use in over-the-counter laxatives because of the possibility of abdominal pain and being a possible carcinogen. Unfortunately, the herbal medicine market has taken up any slack in demand due to the ban.

And now to the dark underbelly of the Pacific Northwest and forest crime, comes the bark bandit. By one estimate as much as half the cascara sold to the health industry is harvested illegally. This is not isolated individuals stripping an occasional tree but organized “criminal rings” – not my words, but that of the Clatsop County Sheriff’s Office in Astoria that busted up their first ring a decade ago. Most legal harvesting takes place either from cascara plantations or from government land, like national forests, BLM land or state forests, through a fee permit. But its suspected that illegal harvesters either don’t have permits, or more typically have permits but take much more than their quota or end up harvesting on private land. If you’re stopped with a loaded truck of bark and a legal permit, whose to say that bark was harvested within quota or on the proper land.

In the Pacific Northwest, forest gang violence is pretty mild. Maybe some slashed tires. but no one’s been found at the bottom of the Columbia with a pair of cascara stump shoes. (Actually that might be more typical of the mushroom hunters, but that’ll be for another edition of True Tree Crime Tales). For now, the violence is mainly aimed at the Cascara.

If this has touched a heartstring as well as incensed you to protect forest family values, you can contribute to Cascara relief by trying cascara as a small native landscape tree in your yard. It may be hard to find and you might need to go to a native plant nursery, but I think its worth the effort. And the next time you’re feeling bound up, try prune juice. There’s no end to the prunes out there.


This is the amazing, thrilling, yet true tale of one tough and controversial tree – Ailanthus, or the tree of heaven. Those are actually the 2 kindest names given to this plant. Other, less complimentary, names include the tree from hell, ghetto palm and stink tree. As you can see, there is quite a dichotomy of opinion about this tree that was imported from China in the 1780’s.

Admiration is in the eye of the beholder and the Ailanthus’s most admirable/despicable quality is its ability to grow anywhere. That trait made it the central metaphor of a famous book and movie of the 1940’s, “A Tree Grows in Brooklyn”

“There's a tree that grows in Brooklyn. Some people call it the tree of heaven. No matter where its seed falls, it makes a tree which struggles to reach the sky. It grows in boarded up lots and out of neglected rubbish heaps. It grows up out of cellar gratings. It is the only tree that grows out of cement. It grows lushly...survives without sun, water, and seemingly earth. It would be considered beautiful except that there are too many of it.”
—A Tree Grows in Brooklyn, Introduction

The love/hate relationship of Ailanthus seems to be affected by locale. In China, its native country, it is used to host silk worms, wood for carvings and its bark and root used in Chinese traditional medicine for treating a variety of medical maladies.In Portland, OR., it is on the prohibited plant list as an invasive species. Because of its aggressive root system, prolific seeding (up to 350,000/year!), smelly flowers and difficulty to kill, it’s a nuisance and therefore the mission is to eradicate wherever practical. I have however seen mature Ailanthus specimens in Lone Fir Cemetery that are quite elegant. In Queens, New York the sculpture garden of the Noguchi Museum was designed around a mature tree of heaven.

Clearly, there is a widely divergent set of opinions regarding this tree. The one thing everyone can agree on is it is tough and has an attitude. I might add, though I can already sense horticulturists distancing themselves, it has character. Plants with “attitudes” have always been denizens of the other side of the tracks. I can just imagine some Norway maple parent chiding its seedlings “Now don’t be going and playing with those Ailanthus kids. They’re plant trash, plain and simple!”

I would never recommend to a client planting ailanthus, unless they were willing to put up with its attitude for the sake of its character. I have often thought, that with the plethora of gardens and arboretums around the world dedicated to showcasing the beauty and positive attributes of plants, I’ve never seen one dedicated to bad plants, born to be wild plants, plants that say, “Eh, oobatz! Come eer! You got a problem wid me?”. The Garden of Attitude – wouldn’t that be an interesting place to visit.


April 26, 2010: This is the amazing, true and smelly story of a living fossil, the ginkgo. The ginkgo tree has resided on this planet for 270 million years, the oldest living tree species on the planet. Living for that long has it drawbacks and benefits. One of the chief disadvantages was that we had to “discover” the ginkgo. After all those millions of years, the last remaining population was restricted to a small area on northwestern China. There are some botanists that argue that even it was not a natural population (it all has a common DNA strain) but a planted one that had been maintained over hundreds of years by Buddhist monasteries. The wild population has vanished, they claim.

In 1780, the first ginkgos were introduced in America. I remember this (no, I’m not that old!) because I used to live near the city of Savannah, Georgia. In that fair city, in their oldest cemetery, Colonial Park, dating back to 1750, there is a block of tall gingkos. I’d like to call them stately, but it’s fair to say that gingko has a rather scraggily form to it at best and when the trees are over 200 years old they definitely show their age. Individual ginkgos are said to live as long as 1000 years, but I imagine that they’re as homely as a mud-rail fence by that advanced age. Oh yes, why I remember these trees so vivid was because of their smell, or rather stink, since I’m waxing poetically about the tree. Ginkgos, you see, are dioecious, that means they have separate sexes, male and female. The female produces fruits that have the most rancid noxious odor of few other things I’ve smelled. I can think of no other comparisons to it except the mysterious stuff my dog finds to roll in every spring and come proudly prancing back to the house. Beneath this noxious fruit however lies a nut kernel that is highly prized by the Chinese as an appetizer when roasted. All I can imagine is that it would take a dedicated gourmand with a gasmask to accrue enough for a Superbowl Sunday party.

But that’s not the only useful thing about a Gingko. Their leaves are the source of Gingko memory supplement and a cardiovascular drug used in Europe. Once I went to a gingko farm in South Carolina. I call it a farm and not a nursery because the gingko was grown like a crop of corn. Closely planted in rows, after 7 years in the ground they were mowed down, the leaves separated and bundled up and shipped off to Europe for the pharmaceutical trade. Gingko as a memory enhancer is now a little in doubt but, when it was not, the gingko became a victim of “leaf larceny”. At Portland Community College’s Sylvania campus, there were several medium size ginkgo that for several years were stripped of their leaves in the middle of the night. 270 million years on the planet and this is the respect they get?

But what I find most amazing about the ginkgo is that it is one of the most tolerant trees around for poor urban soils and air pollution. Now how does a tree that was once thought extinct and found only in a remote forest area of the world take to our cities like flies to rotting ginkgo fruit? I don’t know, but in 270 million years you probably see a lot of changes to your environment including ash and silt strewn soils and volcanic ash filled air. The city must be a pretty puny environment when compared with what it must have through.

I highly recommend the ginkgo in one’s landscape. It has beautiful fall color. Its fan shaped leaves on spurs are a novel feature. You’ve got to respect the character of a tree that’s grown that long. Ah, but the stink? How will I know I’m buying a male, not a female tree? Take comfort, the nurseries now sell a sterile ginkgo. No appetizers, but you can sleep with the windows open at night.


April 21, 2010: Hmmm. My very first business blog entry. My problem is I’m really not sure what a business blog is (as reader is warned above)! From what little I’ve garnered on the Internet, a business blog can be the personal face of the business, an extended advertisement, the inner thoughts and musings of the CEO, offer helpful and timely technical information, among other things. Well, I’m not sure even myself would be all that interested in reading my inner thoughts; there are a lot better researched and organized websites for technical information that this; I believe there are limits to how much you can batter a reader over the head with advertising; and a personal face to the business – well that is a worthy goal, but also a wee bit too ambiguous to get me started.

I have been blessed, at least many more times than cursed, as being a teacher whose subject matter was plants. The botanical world as one’s curriculum guide will never leave a teacher bereft of interesting anecdotes and curiosities to help illustrate biological concepts and principles. So that’s how I’ll start this blog. Amazing, Thrilling, Yet True Tales from the World of Plants!


Once upon a time, there was a war, the American Revolution, and there was a tree, the palmetto, and there was a very pivotal location to that war, the port city of Charleston, South Carolina, and all three of these things came together in a serendipitous fashion to create one of those moments that the history of the world (. . . or with less hubris, just the USA) hinges on the outcome.

Early in the Revolutionary War, the British we still the favored winner and being somewhat tired of the pesky American rebels, they determined to make a decisive blow to end their troubles. They determined that blow would be the capture of the Southern coastal ports of Savannah, Georgia and Charleston, South Carolina. Considering the rag-tag nature of the American army this would be a simple matter and once the ports were captured the South would be out of the war and the North would then quickly succumb to the British military. They sailed a fleet from Boston to the harbor outside Charleston to quickly capture the city. Alas, the British never even factored in the Americans secret military defense – the palmetto tree.

As the British were sailing to Charleston, the Americans began fortifying the entrances to the harbor at Sullivan’s Island. In command of the defenses was Colonel Moultrie, a Lowcountry planter. The fort he built on Sullivan’s Island, which was only half completed on June 28, 1776 when the British arrived, was considered by many to be a worthless defense. Rather than being built of stone or stout timber walls, the walls were constructed of palmetto trees, a local palm. I’m sure the British guffawed at the sad attempt the colonialists had made to stop their naval juggernaut . . .but the last laugh was on them!

The palmetto, a palm, is a monocot, one of the 2 large groups of flowering plants. It has more in common with a blade of grass or an onion anatomy-wise than an oak tree and it is that anatomical difference that saved the port of Charleston and our fair nation. Palmetto tree at Radford LandcarftYou see monocots have their vascular system, the xylem and phloem (think like veins and arteries in people) in bundles located throughout the trunk and surrounding those bundles are spongy fibers. In contrast, what we typically think of trees, oaks or Douglas fir , are dicots and they have their vascular system separated in rings around the trunk Much of the older vascular system turns into wood or bark eventually, but the result is a harder and stronger trunk in many respects.

Now, back to our shabby unfinished palmetto fort. As the British cannon fire found their mark on the logs of the fort a most curious thing happened. Rather than creating a shattering explosion that would eventually batter down the walls to rubble, the cannonballs harmlessly bounced off. Volley after volley proved ineffective to subduing the fort, while the Americans proved most effective in damaging the British fleet. Short on ammunition (only 28 cannonballs per cannon), Colonel Moultrie ordered his batteries to fire only 1 ball per 10 minutes. This gave lots of time to aim and proved quite deadly to the British fleet. They learned when you’re hiding behind palmetto logs, you’ve got time to do it right.

Eventually, a frustrated and demoralized British fleet, pulled up anchor and sailed away. Days later, Charlestonians learned of the signing of the Declaration of Independence. The American victory turned the populace of the South to the Rebel cause. South Carolina flag at Radford Landcarft It wasn’t until 3 years later that the British returned and captured Charleston by land, but by then it was too late to be decisive.

And so, dear reader, the homely palmetto tree with its unique anatomy saved our fledgling nation when it was most vulnerable. The citizens of South Carolina in recognition and gratitude placed the palmetto front and center on its flag and nicknamed itself The Palmetto State. It’s the only state flag to have a tree on it. It is amazing, it is thrilling and yet it’s true!

F & P