A Little Bit More
Cut off the tips from any tree or shrub or the end of a flowering plant and that end won’t grow any longer, ever. Oh sure, side branches can take over and begin growth but the cut portion itself doesn’t extend any farther. On the other hand, you can cut your lawn and the same stalks of grass will come back for more, and more, and more. Grasses grow at their nodes, or joints, and the lowest node (the only one we generally allow our lawn grass to have) is too close to the ground to be destroyed by our mowers. This adaptation is an excellent one to overcome the depredations of intense grazing. Mow any field, even a very shaggy field of wildflowers and brush, and keep it regularly mowed and the grasses will win out; you’ll end up with a smooth, green swath with only a handful of plant species, dominated by grass.
It’s interesting to note that only recently has it been learned that the grasses have existed since the Cretaceous period. It had been believed that the grasses didn’t evolve until AFTER the demise of the dinosaurs. Until recently, the oldest grass fossils scientists knew about were 55 million years old (dinosaurs died out 65 million years ago). However, recent studies of fossilized dinosaur dung, called coprolites, indicate that dinosaurs were indeed feeding on grasses at least 71 millions years ago – at least 6 million years before their extinction. Looks like the grasses have been with us for a long, long time.
Activities
Science – Sprouting Grass
Objectives: See grass germinate
Materials: Grass seed, plate, and paper towels
Seeing seeds germinate is always interesting so try this simple exercise with your students.
1. Obtain some grass seed (you don’t need much so one of the student’s parents may have some to share or the local hardware store may just give you a small handful).
2. Place a paper towel on a shallow object (small plastic plate works well) that can get wet and remain wet for several days
3. Lightly sprinkle grass seed on the paper towel
4. Place a second paper towel over the first and wet the two. You want the two paper towels to be thoroughly moistened.
5. Place this setup in a warm part of the room and keep an eye on the towels so they remain moist (don’t have to be soaking wet but don’t let them dry out either) at all times. You may even want to place a plastic bag over this, especially overnight, to prevent the towels from drying out.
6. Watch the seeds daily and soon you should see the seeds swell and begin to sprout.
7. If you want, you can gently place these seeds on some soil and allow them to root and grow once they’ve begun germination. Sprouting seeds is a bit like birth, always an amazing sight to see seeds become living plants.
Key Concepts
Structures and Functions, Identification, Growth and Development, Adaptations and Diversity
Questions
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