Archive for November, 2010

Since moving to St. Paul I’ve been exploring a lot on my bike, but a couple weeks ago (before the snow blew in) I got a history lesson in my own yard. And it was putrid. Rancid, even. But enlightening.

I love fall. I love the colors, the crispness in the air, the sound of leaves blowing around on the ground and crunching underfoot, their distinctive smell. It was a brisk fall day and I though it would be a good idea to rake all the leaves that had dropped. Not only would I be doing a good deed, I would get fresh air and exercise. It would only take an hour or so.

The house sits on the corner of the block and there isn’t much lawn. I quickly worked my way across the backyard, where the leaves were thickest, along the boulevard to the front, and then got to work on the front yard and boulevard. I had left them till the end because they are small and a cursory glance indicated that they didn’t have many leaves. Two small apricot trees stand on the front lawn, a maple stands close to the corner on the side boulevard, and a medium-sized tree graces the front boulevard. It would be a snap.

Ginkgo tree that has lost its leaves in the fall.

Mysterious tree on the front boulevard.

Once I got within ten feet of that tree on the front boulevard, my idyllic autumn interlude came to an unpleasant, malodorous end. I don’t have the greatest sense of smell in the world, but it took no time for me to discern the scent of vomit and dog poo. I remembered what my friend had said:

Beware of the stink fruit!

There were so many questions:

  • Why does this tree produce noxious but innocent-looking fruit and the one in front of the neighbor’s house with the same kind of leaves doesn’t?

    A single ginkgo fruit lying in the grass.

    Who would expect such a harmless-looking fruit to emit such a rancid odor?

  • Why would anyone choose to plant a tree that produces stink bombs in the fall that fall to the sidewalk and street and get smashed by feet and tires, thus releasing the disgusting fumes into the air and contaminating shoes with toxic waste?

    Ginkgo 'fruit' smashed on the pavement.

    And yet if you value your shoes, don't step here!

  • While we’re at it, why is this street lined with just ginkgo trees while the cross street is lined with some kind of maple?

You may already have guessed that the unassuming tree on the front boulevard is no ordinary tree; it is a ginkgo tree. A female ginkgo. And here is where the history comes in, not to mention a little biology. It turns out that ginkgo trees are dioecious, which means that the male and female flowers appear on separate plants. The females fruit while the males do not. Ash, boxelder, juniper, cedar, and holly are all dioecious, but it is only the female ginkgo that produces such an objectionable but benign-looking fruit.

Ginkgo 'fruit' left on the tree after all the leaves had fallen.

Ginkgo 'fruit' left on the tree after all the leaves had fallen.

Given this substantial drawback, why did the city plant this female ginkgo tree (and several others along the same street)? It turns out that ginkgoes have several things going for them. They do well in urban environments with disturbed soils, they tolerate air pollution, and they aren’t prone to problems with pests or disease. Furthermore, the ginkgo will eventually develop into an attractive shade tree, although ours hasn’t made it to that height yet. Ginkgo leaves are a unique fan shape and turn a brilliant golden color in the fall. These were all probably important considerations.

A neighbor told my friend several years ago that this street used to be lined with large elm trees that formed a leafy cathedral ceiling above the street. When they were decimated by disease in the 1970s, apparently the city decided to replant the boulevards using a different species for each street. That way if one species were hit with a new disease, only one street would be affected, not all the streets in the neighborhood. This street hit the jackpot with its ginkgoes!

Today most ginkgo trees are grown from cuttings from a male tree grafted onto a seedling rootstock so that the resulting tree will be male and will not produce offensive stink bombs in the fall. If grown from seed, the sex of the tree might not be distinguishable for ten to twenty years, when the tree is finally capable of flowering. So either the City of St. Paul wasn’t concerned about the sex of the trees or this tree was too young for its sex to be determined when it was planted.

Much as I hate to admit it after an afternoon cleaning up ginkgo fallout, the ginkgo is a fascinating species. It is often called a living fossil (although I believe this is a misnomer, since as far as I’m concerned fossils should be unscented) and has been around for over 270 million years. It lived through the age of the dinosaurs and survived down to the present day in a small area of central China where Buddhist monks apparently kept ginkgoes alive near their monasteries for more than a thousand years.

The ginkgo has no living relatives. What we think of as the fruit of the female ginkgo is really a seed surrounded a hard shell and then by soft and fleshy section. The nasty stench comes from butyric acid in the ‘fruit.’ The fan-shaped leaves are unique as well. If you look closely, you can see fused needles in the leaf. Ginkgoes represent a link between needled evergreens and broadleaf deciduous trees.

Golden ginkgo leaf

Ginkgo leaves turn a beautiful golden color in the fall.

As I looked into the history of the ginkgo, I also discovered that its survival capabilities are downright impressive. Forget standard American urban air pollution: several trees survived the 1945 atomic bomb blast at Hiroshima when all other life was destroyed. These trees are still alive today. No wonder the Japanese call them the “bearers of hope.”

I vaguely remembered learning about the gingko in a college biology class, but this was my first close encounter with one. I appreciate the chance to learn something new about my community and the outdoors, but I’m hoping the next lesson won’t be quite so … um … fragrant.


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An Engineering Gem

The Twin Cities has some amazing bike trails. Who would have thought that it would be safer to bike in the cities than out in the exurbs? Despite the open spaces, there are few trails or shoulders to ride in exurbia, so I jumped at the chance to get some exercise and explore my new home at the same time once I settled in St. Paul.

Besides enjoying our gorgeous fall weather (now sadly departed!), I discovered some real gems on my rides, both scenic and historical. Biking the Bruce Vento Regional Bike Trail from Lake Phalen to downtown St. Paul took me through the Bruce Vento Nature Sanctuary, a peaceful spot below the bustle of East 7th Street and Payne Avenue. The sign post along the trail introduced me to the name Swede Hollow.

Signpost along the Bruce Vento Bike Trail

On my first ride along the trail I noticed the stone arch bridge. Actually, I thought of it as a tunnel since I was riding through it, not over it. The bridge stood out to me because of its interesting design: the stones in this bridge seemed to be set in a kind of swirl or spiral. I wondered if there was any structural significance to this or if it was just for aesthetic purposes.

The Stone Arch Bridge over the Bruce Vento bike trail, Swede Hollow.

I also became fascinated by the idea that people (among them Swedish immigrants, amazingly enough!) had lived down in this narrow valley, so I visited the Ramsey County Historical Society to see what I could find out.

While once there were trains chugging along the tracks (now the bike trail) down in Swede Hollow, today the sounds of the city are somewhat muffled. Instead you can enjoy a peaceful respite from the bustle above on the street and imagine what it would have been like to live down in this narrow valley with its steep walls. Were you snowed in during the winter? Where did you get your water from? What was it like living so close to the tracks? More on that in a later post

While browsing through the RCHS folder on Swede Hollow, I came across a newspaper clipping from the Pioneer Press dated 28 May 2001. There was a picture of the very bridge I had wondered about. It turns out that my non-engineering instincts were right on: this is a special bridge.

The bridge was built in 1883-1884 using a technically demanding technique described in the article as “skewed, heliocoidal, stone-arch design.” It turns out the stones are all the same size and shape, hand carved with great precision.

Detail of hand-cut stones in stone arch bridge.

Detail of hand-cut stones in stone arch bridge.

The civil engineer who designed the bridge, William Albert Truesdell, chose this type of construction because he had to address the problem that the railroad tracks (now the bike trail) crossed the road’s path at a 63-degree angle. He had read about the technique and knew that this method would use less building material and still safely distribute the load the arches had to carry. Since mathematics was his hobby, he was able to calculate the correct size and shape of the blocks, but then he also had to impress on the laborers how important it was for them to be accurate in their cutting.

The bridge was declared to be a national historic civil engineering landmark in 2001 by the American Society of Civil Engineers. Apparently this type of bridge is very rare with one or two known in Pennsylvania.

I was intrigued by the bridge before I learned anything about its history or construction, but knowing the skill and care that went into its construction 125 years ago increases my admiration for the people who built it. I wonder how many other riders have wondered about this bridge as they passed below it. And how many riders realize that this peaceful spot was once the home to many immigrant families.

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History is fun. History helps us understand how things came to be the way they are and links us to the joys and sorrows, successes and failures, of those who came before us. It gives us perspective on the past and informs our choices about the future.

And yet many people seem to have been traumatized by their high school American history class where they were required to memorize names and dates and places without anyone pointing out why that knowledge might be useful to them. Classroom history often strips history of the basic human element that makes it interesting and relevant.

People might not like “history,” but ten years of working in museums has shown me that people do like stories. Much of history is just that – stories – but put into context so they become meaningful and relevant to the individual. Those stories can enlighten us, or make us laugh, or shock us and make us thankful we live today. (Or perhaps wish that we had lived in another time, without cars and electricity and computers.) But history done properly should touch us, inspire us, elicit some kind of response.

We live in a mobile society and spend much of our time whizzing past places in cars or buses or trains, unable to stop and really look at the places around us. Many of us spend more time commuting or sleeping than exploring our own communities. It doesn’t take long for communities (especially fast-growing ones) to lose their individuality as the stories and landmarks that made them unique are forgotten or lost.

So much of history isn’t visible on the surface; you have to look for it. Get out for a walk or take your bicycle out for a spin, add a measure of observation and a dollop of curiosity, and you’ll be surprised at the stories that lurk beneath the surface of your neighborhood that link you to the people who came before. Chat with friends and neighbors and listen to their stories. You never know what you’ll find out.

I’ll be exploring the Twin Cities area as a newcomer, trying to discover the stories of the people who built my adopted hometown and made it what it is today. What better way to connect with my new home than learning the stories of the places I see regularly as I go about my business?

Some of my ‘discoveries’ may be old hat to longtime residents even if they’re new to me. You never know, I might stumble across something new to you, too. So come along on my rambles. And let me know if you know some good stories about this place we call home.

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