Thursday, April 19, 2012

Hands-on Botany

All real botany is a hands-on experience. I wish we all had more time to get out in the field and see, hear, touch, smell, and taste the wonders of the Plant Kingdom. For my students at the Boston Architectural College getting out into nature is a real luxury. For their degrees in design, architecture, and landscape architecture, these fine folks are required to work during the day and take classes at night. How many times have my students dragged themselves in to class at 5 PM when the rest of the world is kicking back with something red?


So I was super pleased that the weather last Sunday was picture perfect for our field trip to Mount Auburn Cemetery, a national historic site and the nation's first landscaped cemetery, right here in Cambridge. The flowers were luxuriating in the gentle spring sun, leaves unfurling, buds ripening, and hawks soaring overhead.

Designers in Nature

All this without the usual pesky insects of summer, so in a sense, we had it all.

I've written on these pages before about my BAC students but let me just say it again. The way these people approach learning, observing the world, and thinking critically about nature and design, is a true inspiration to me!

My BAC Posse Spring 2012

Friday, April 6, 2012


It all started a couple of months ago when I noticed the worms' habitat was looking and feeling kind of gummy. This wasn't the kind of soil I'd want to put into pots for my houseplants. So I started to think about it. What was missing? I used the usual method for problem solving, sleeping on it. And I woke up with an idea. The soil needed some grit. The worms too for that matter.

Death Valley Arroyo

So we bought a fifty pound sack of sand and about once a week I added some sand to the worm habitat. I observed that where sand had been mixed into the soil there were more worms. And soon I noticed that there were more baby worms around there too. So I thought about it some more and remembered long long long ago when we did worm dissections in high school. We learned then that worms need some sand in their gut to help them digest their food.

Worm castings

This got me to thinking more about worm nutrition and the balance of worm habitats we want to achieve for optimum worm "performance." If I had neglected grit all these months what else was missing?

Urban composting

So I started looking more carefully at the worms in their recycle bins. Always I had thought they were pretty happy! But now I noticed a few more things. First, there were certain things that didn't disappear that quickly. Large pieces of cabbage for example. Aha! Cut things into smaller pieces for the worms!

Beautiful meal

Then I noticed that certain parts of the recycle bins were dry and others much wetter. I realized that the wet parts were kind of rotten smelling and the dry parts didn't have much worm action going on. Solution? Mix the soil frequently. The smell disappeared right away and overall I saw more worms squirming around all through the environment.

Lignin Leaf Skeleton

Then some of my students did a presentation on composting. In addition to a good balance of oxygen they reported that composting environments need a balance of carbon vs. nitrogen. Carbon comes from the cellulose-rich things we add to the compost, like pressed cardboard egg cartons. Nitrogen is from the protein-rich leaves and veggie peelings we add.

Spinach closeup

Protein-rich leaves?? Well it all boils down to the structure of plant cells, which are surrounded by an indigestible cellulose cell wall. The proteins in the cell run the photosynthetic process but they are unavailable to us because we can't break down cellulose. When micro-organisms in the soil break down that cellulose the proteins in the leaves and vegetables become available in the worm environment.

Lemon Zest

This got me thinking about something else. Have you ever seen a worm biting into a leaf? How were they getting their nutrition? It always surprises me that as a professor who teaches this stuff there are many things I haven't thought through all the way. I'm always teaching that the soil is alive with zillions of micro-organisms. Somehow it hadn't occurred to me that the bacteria, fungi, and other microbes in the soil break down organic matter that's there. In the worm bins, these microbes are the first stage in breakdown of stuff we put in.

Mud "Cells"

The worms ingest partially broken down materials and in their guts, more microbes break the materials down thoroughly, mostly producing carbon dioxide.

Air pollution

It's not the easiest thing to grasp at first, but it's not rocket science either. All natural environments have some kind of balance. In the worm environment we're working on there's a balance of oxygen, water, nutrients, organic matters and particles of grit. It's a work in progress but an amazing one. The more I work on it the more I learn.

Verdant Ocosingo Valley

Tuesday, April 3, 2012

Evolution of Flight

What a wonderful innovation it was when plants learned to fly. Plants? Flying? The ancestors of plants left the water about 350 million years ago during the Devonian. They were accustomed to hanging out in or near the water and the first plants were probably pretty soggy. For the most part mosses, which are most similar to the ancestral plants, also like moist environments. They reproduce by sperm, which are carried by raindrops to a nearby egg. Mosses are pretty but they don't fly.


Magical Understory at Yoho

Moss Clump

But almost simultaneously with the emergence of mosses, genera like Selaginella came into their own. Selaginella plants sent their spores flying into the air, perhaps the first instance of a flying plant, or at least part of one. A modern-day example of Selaginella is the common ground pine of northeastern woodlands. Before the flash bulb was invented, the copious spores of ground pine were ignited to produce a burst of light for old time photographers, a great example of plants in the service of art.

The ability to travel by air must have provided a profound selective advantage for plants that could do it. Spores, pollen, and later seeds could disperse in every direction, landing in new habitats and colonizing them.


Pine strobilus

Quercus catkins

Developing pistilate flowers

Some plants, for example grasses, reproduce exclusively through the agency of wind. A month on the Canadian prairie showed me how well grasses were suited to a windy environment.

I imagine that wind pollination had some drawbacks though. For example, since dispersal is random it means that the plant has to produce many more seeds or pollen grains than will survive. My guess is that the benefits far outweigh the drawbacks. The plasticity of plants, whether we think of it in terms of their ability to fly or their ability to evolve into new habitats, is one of the most amazing things I can imagine.