Thursday, September 23, 2010

Static or Moving?

The first thing you learn in any botany class is that plants are “sessile” organisms, entities that don’t move. From one perspective, this is patently obvious. As I look at the Dawn Redwood (Metasequoia glyptostroboides) outside the window of our new Main Library, it’s quite true that the tree is standing in place. In that sense it is sessile. In front of the tree are people on bicycles, parents pushing prams, pedestrians whose legs, arms, hands, and feet move as they walk, talk, and raise a cup of coffee to their lips. In the background I look out at Cambridge Street, a line of traffic in the distance going east and west, cars, tow trucks, more bicycles. The entities in the foreground (people) and background (vehicles) are structurally and behaviorally complex. Part of their complexity is defined by the fact that they are moving. What about the simple, sessile Dawn Redwood in the middle ground?
It barely takes a second look to see that the Dawn Redwood tree is moving. Its trunk is straight and tall and unbent, but every branch moves in the breeze. As I look more carefully I see that the branchlets hanging from the main limbs are moving too. I put on my glasses and see that every leaf of the tree is in motion. The Dawn Redwood, the weeping willow nearby, and the majestic copper beach to the right are all moving in concert with the breeze. Is it sophomoric to note that the trees are moving? No, not in the context of established plant knowledge that tells us plants are sessile. We’ve taken the first step of good design, the first step of any critical thinking, by challenging the “rule” that plants are sessile.
Let’s explore plant movement a bit further. The Dawn Redwood didn’t grow on this spot from a seed. It was moved in fact, as a sapling, on the back of a truck, another obvious point, perhaps. The tree was planted here (moved here that is) fifteen or twenty years ago. But considered within a broader time frame (one that takes into account “deep evolutionary time”— a scale that counts in the tens of millions of years), we can conclude that the Dawn Redwood as a species has moved in a much more profound way through migration. Not just a truck ride from nursery to city, the Dawn Redwood has traveled through time between continents and hemispheres, journeys that brought it to radically distant parts of the planet. Simply, plant migration takes into account advances and retreats, often involving thousands of miles over thousands of years, of a given species. Plate tectonics, climate change, rising and falling seas, competition from other species, all have influenced the movement of the Dawn Redwood and every other plant species over time. These Earth-altering events have also influenced the movement of the beech and willow trees that grow on the library lawn. The Dawn Redwood growing in front of the library may have spent its early years at a Boston area nursery, and its ancestors may have grown near here tens of millions of years ago, but its recent forebears hailed from East Asia. Roughly 50 million years ago, on an Earth with a radically different climate from today’s, the Dawn Redwood ranged far north of the Arctic Circle. In the intervening tens of millions of years its range retreated to present-day China, where it was “rediscovered” in the twentieth century by Western botanists and brought back to North America as a decorative species. Now it is widely planted in cities with a temperate climate. I always take students to the Arnold Arboretum in Boston to see specimens of this species that truly “look” prehistoric. The individual trees themselves aren’t that old but there’s something about their shape as they grow brooding next to a body of water that reminds us of the dark days of dinosaurs. Who knows whether or where this species will migrate in the future? But the presence of this “living fossil” on our library campus in Cambridge Massachusetts reveals a lot about how plants move.
As a professor at the Boston Architectural College I’m also interested in the way designs migrate, move, and are “re-discovered.” It’s easy to say that tastes change and ideas about taste change. But new understandings are also being grown. My BAC students consider design in terms of new ideas about sustainability. At the same time they’re considering new architectural ideas by studying ancient vernacular building designs. In my class we class study how plant-based design patterns like lotus buds, cypress trees, acanthus leaves, or corn cobs have migrated among peoples and taken on new lives in different times among different cultures. In an environment where we export design and assimilate new design ideas it’s clear that design, like plants, is anything but static.


  1. Really insightful! If we comprehend the way plants move in an anatomical fashion, as well as historical fashion, we might be better able to understand that plants are not static at all. They are always moving! -from Tess Velasquez, MET IS 380 Group 1 Student

  2. Just started reading "Hawaii" by James Michener and in the beginning before Hawaii was barely an island he spoke about the land being seeded by a bird who had eaten a seed, defecated & "planted" new life with the seed. It was millions of years ago & while it's still fiction and partly speculative, Michener is known for his thorough historical research. It is mind-boggling to think of things like the migration of plant species but this article was my favorite out of the three.

    The noni fruit is another amazing plant design. It's yellow & looks a bit alien-like with several "eyes." I wonder about its origin & relation to other plants....

  3. Now that I read this essay, “sessile plant” is an oxymoronic term. It is a term that is understood by human from observation at the most shallow level. Plants move, it grows upward, stretches sideways and also hunches down like any other living organism. Plants are also moved from locations to locations by human, nature’s force or simply by wind as an example. Based on Pangaea theory, many plants are migrated or separated and can be found on many different continents.

  4. Interesting article! I remember learning about plants being sessile in botany w/out borders. To exist, a plant must search for sunlight and adjust accordingly. It must spread its roots to absorb water and it must expand as it grows. Even for a tree - which seems to stay in place - there is constant movement!

  5. While the detail oriented side of me wanted to argue that plants are sessile because they don't displace themselves spontaneously with intention, I thought the better of making an argument that Dr. Hammer deemed "obvious". Once I let go of that, I realized that this article made me remember some wonderful sunflower fields I had seen when driving through Poitiers, in France. Like many plants, sunflowers move to follow the sun. Their French (tournesol), Spanish (girasol) and Italian (girasole) names are a tribute to this movement. Shall we rename them in English to "Turning towards the Sun" flowers ?
    Kayali Lenssen-Spiller - IS380 Group 1

  6. I was really taken by the comments made about migration. It really got me thinking differently about how plants, trees, etc. "got here." Washington D.C is having the Cherry Blossom Festival next week. A gift from Japan in 1912, the trees are not native to D.C. for sure, but something that has become as much a part of Washington as of the numerous moments that dot the city.

    Your blog has me curious about the Cherry Trees actual migration!

  7. When I read this article, I get the idea that specific plants are manifested in different parts of the world at different or at the same times, because they can move. Is it possible for the same species of plant be manifested in different parts of the world without movement?
    Maybe, instead of relating "sessile" with lack of movement, I could think of it as the articular way in which plants move. Would it be correct?