Determine the range for your topic. You can research and write in great detail about one specific species of plant, such as the strawberry plant. Conversely, your research area could be a very broad-based topic, such as why conifers, such as pine, fir or spruce trees, do not lose their leaves in winter.
After you choose the range, choose the theme. Some themes include plant diseases, plant growth cycles or how pollution affects plants. High school science teacher Elizabeth Coveney at Patchogue-Medford High School of Medford, New York, notes that by and large, air pollution is detrimental to plants. Give the theme a narrow base, such as how pollution affects the strawberry plant, or a broad base, such as what medicines can be derived from plants.
Research a particular region, such as tropical or aquatic plants. In a regional approach, research various aspects like how a drought affects the plants of the mid-west or how pollution affects aquatic plants. Within a region, you may choose to further specialize into a specific topic, such as invasive plant species or why tropical algae blooms form.
Since the field of botany is so vast, it is possible to combine two or more research ideas to form a final idea. For example, combine a species-specific topic with a regional theme. One such idea is how to overcome the invasive kudzu problem in the southeastern United States. Another idea is to research how pollution runoff affects algae growth.