The Twisted Grove of Nisene Marks State Park

 First Quarter Moon

This past Monday I returned to the Magical Forest of Nisene Marks State Park in the company of my semi-notorious friends Captain Chem, Sultry Sue, and Saint Nacho the Chihuahuan Empath. This visit had the twin purposes of a) finding the much ballyhooed "Twisted Grove" of redwoods and b) enjoying a picnic lunch at the end of the Old Growth Loop trail. I successfully checked both items off my Monday to-do list.

Now I have another thing to-do. I have a Facebook friend who has sort of been bugging me for a while to find the Twisted Grove and report on what I saw. Her interest prompted me to think the grove might be both hard to find and somehow very spectacular. It was neither, really. It's only a half-mile, if that, from the park entrance and it was easy to spot on the park map. This small grove of twisted trees uphill from Aptos Creek exhibits a curious thing called spiral growth. They are interesting, but unspectacular, at least until you start to learn the how and why these trees grew in spirals. 

They are cool-looking, though. My photos did not turn out so well, so I borrowed a couple from my San-Juan-Bautista-by-way-of-Soquel friend Katie Smith.

Photo credit: Katie Smith

Photo credit: Katie Smith

To understand how these trees got so twisted, I turned to Dr. Maynard Moe, a retired Biology professor and plant expert/naturalist/hiker/backpacker who grew up in Yosemite Valley, yes that Yosemite Valley, in you know, Yosemite National Park. The good Dr. Moe allowed me to ask one dumb question after another as I scoured the web for an explanantion that wasn't pure speculation. He helped me eliminate a few wild goose chases and he didn't once come out and say "Geezuz, Jim, you really should be in a home by now." Heckuva nice guy, that Maynard. 

To begin to understand what happened to these redwood trees that made them grow in spirals, it helps to review a few terms from high school daze. I'll go ahead and preface all of this by telling you two things: a) this will be a very simplistic explanation and b) the exact mechanics and causes of the process are still being studied. How is that for lowering expectations?

For a little review of how trees get water and nutrients from their roots to their branches and parts farther out on a limb, I'm going to quote some folks from the University of Tennessee who know what they are talking about. 

Tree Growth Characteristics 

 https://extension.tennessee.edu/publications/Documents/W227.pdf

Upon peeling the bark off a branch, the soft inner layer of bark next to the wood is revealed. This is the vascular cambium, and every year it creates xylem (new wood) on the inside, and phloem (new inner bark) on the outside. The xylem carries water and nutrients from the roots upward, while the phloem carries sugars from the leaves downward (Fig. 4). In temperate climates, the cambium does not grow during the winter and a dark line can be seen in the wood where cambial growth slowed at year’s end. These are the annual growth rings that are visible in many species.

A certain amount of diameter growth also occurs through growth of the cork cambium, which produces cork, the outer layer of bark. New cork is produced each year; however, the outermost layer is shed so that the bark thickness of a mature tree remains nearly the same from year to year. Therefore, while growth of the cork cambium may contribute greatly to diameter growth as a sapling develops a thick bark, diameter growth of a mature tree is mainly due to the production of wood by the vascular cambium. 

Okay, so the root system transports water and nutrients up through the xylem to the branches, right? As long as the roots are intact and functioning "normally," the water goes pretty much straight up the tree above where the root system is feeding it all around the circumference of the tree. Absent any funny business, what you get eventually is a big ole beautiful straight redwood. 

BUT, what happens when the roots are not functioning as described above? What if, for example, the roots on one side of the tree get tangled in rocks and can no longer reach soil to transport water? What if that or another external stress changes the straight upward movement of fluids through the xylem on one side of a tree?  Then you get blockage called cavitation, creating an embolism.

Cavitation occurs in xylem of vascular plants when the tension of water within the xylem becomes so high that dissolved air within water expands to fill either the vessels or the tracheids. The blocking of a xylem vessel or tracheid by an air bubble or cavity is called as embolism (Gr. embolus, stopper), and such a vessel or tracheid is said to be embolized.

https://www.biologydiscussion.com/plants/cavitation-and-embolism-in-vascular-plants-with-diagram/22732

An embolized xylum vessel will prevent straight upward movement of fluids from the roots to the branches, so for the tree to grow, something  must give. Of course, nature finds a way. The tree compensates by an adaptation called spiral growth. Fluids move around the blockage (embolism) at about a 30-degee angle and begin a spiral journey around the tree like stripes on a barber pole, thereby bringing fluid to all parts of the crown, not just the parts directly above the healthy side of the root system. The end result is the twisted form exhibited in the Twisted Grove at Nisene Marks. 

Simply stated, spiral growth is:

an adaptation that resists the "upstream" effects of embolisms. If embolisms aren't an issue, there is no selection for twisting. – Dr. Maynard Moe. personal communication

In the hundreds of redwood trees that surround the tiny Twisted Grove in the Magical Forest of Nisene Marks State Park, there are no consequential, bothersome embolisms and thus, there is no spiral growth. 

I for one am happy the twisted trees and their embolisms allowed me to visit and wonder how they came to be. Did I arrive at an exhaustive answer to why and how spiral growth occurs? Nope. But at least I gained a basic understanding of what may be the process that produced the result. And I learned to be cautious and dubious while reading speculative, data-less answers like the Coriolis Effect and earthquake shaking self-correction on the internet. 

No doubt, I will learn more as time goes on. That's entertainment.

Peace, Love, and Picnics,

Jim