The Chemical Weapons of Forest Plants: A Source of Medicinal Inspiration for Humanity
Text and photos / Taiwan Forestry Research Institute, Council of Agriculture
Why do some plants have no insects to be found on their leaves, while others can give off a pleasant fragrance? The Taiwan Forestry Research Institute points out that some plants, in order to protect themselves, can secrete special odors to drive away visitors, and these volatile chemical weapons are the secondary metabolites within the plant body known as "essential oils."
The Lianhuachi Research Center of the Taiwan Forestry Research Institute is located in the mountainous area of Yuchi Township, Nantou County, and has more than 460 hectares of experimental forest land. It preserves a complete low-altitude natural broadleaf forest and nurtures a rich variety of plant species, making it an extremely precious wild plant gene bank. In recent years it has collected many plants with special odors, such as Taiwan cinnamon (Cinnamomum insulari-montanum), mountain pepper (Litsea cubeba, also known as maqaw), Zanthoxylum ailanthoides, Evodia fargesii (also known as Evodia lepta), Clausena excavata, Sichuan pepper (Zanthoxylum bungeanum), Taiwan fragrant lemon (Citrus depressa) and so on, all of which are rich in essential oils and have strong aromatic and pungent odors.
The special flavors produced by these plants can be used as spices in food, enhancing the flavor of dishes, and can even be used in folk medicine. The early settlers who came to Taiwan used the special components of these plants and developed many folk remedies and prescriptions. Since the chemical weapons of these plants can repel insects and are also edible, there are countless special components among them worth developing and utilizing.
There has already been quite a lot of research on plant chemical components in recent years. For example, the essential oils of Taiwan incense cedar (Calocedrus formosana) and Taiwan hinoki (Chamaecyparis obtusa var. formosana) can be used for anti-inflammation, and the fruit essential oil of Taiwan cinnamon also has significant anti-inflammatory activity. Rutaceae plants such as Zanthoxylum ailanthoides, Clausena excavata, Evodia fargesii, Sichuan pepper and Taiwan fragrant lemon all contain essential oils with unique odors, whose components include pinene, myrcene, limonene, safrole, eucalyptol and so on, with a pungent aroma that can drive away certain insects.
The research team of the Taiwan Forestry Research Institute is carrying out germplasm collection and analysis of plant essential oil components through the "Medicinal Plant Germplasm Collection and Utilization Project," conducting controlled experiments to understand the relationship between insects and plants, and using the special components of essential oils to produce repellent, driving-away and concentrating effects on insects, or antibacterial and allelopathic effects, using mixed planting, planting tree species with effective insect-repellent properties in farmland, afforestation land or their surroundings, or spraying essential oils at different concentrations to achieve a shielding effect, reducing or repelling harmful insects and disease-vector insects, achieving the goal of pest and disease control, and developing ecological control techniques for agroforestry management.
Huang Yuxing, director of the Taiwan Forestry Research Institute, stated that there are still many plants with medicinal functions in Taiwan's forests that have not yet been developed, and the research team of the Taiwan Forestry Research Institute will also continue to work hard, applying research and development results to practical operations, so that the treasures in the forest can create even greater value.