来源：沪江听写酷 2011-11-12 12:03
OK. In the last class we talked about the classification of trees, and we ended up with a basic description of angiosperms. You remember that those are plants with true flowers and seeds that develop inside fruits. The common broadleaf trees we have on campus fall into this category, but our pines don't. Now, I hope you all followed my advice and wore comfortable shoes because, as I said, today we're going to do a little field study. To get started, let me describe a couple of the broadleaf trees we have in front of us. I'm sure you've all noticed this big tree next to Brant Hall. It's a black walnut that must be 80 feet tall. As a matter of fact, there's a plaque identifying it as the tallest black walnut in the state. And from here we can see the beautiful archway of trees at the Commons. They're American elms - the ones along the Commons were planted when the college was founded 120 years ago. They have the distinctive dark green leaves that look lopsided because the two sides of the leaf are unequal. I want you to notice the elm right outside Jackson Hall. Some of its leaves have withered and turned yellow, maybe due to Dutch elm disease. Only a few branches seem affected so far, but if this tree is sick, it'll have to be cut down. Well, let's move on and I'll describe what we see as we go.