In our daily lives, we're surrounded by herbs in the form of salads, teas and medicines; if a plant's usefulness is not especially obvious, it stands the risk of being called a weed, instead. However, the term we learnt in school - small plants with soft stems with minimal amounts of woody tissue - remains a good definition for herbs, even as we use the word for all plants with culinary, cosmetic, medicinal and fragrant properties.
This may be due to the herb species domesticated by men centuries ago, and remain highly used, for fragrance and medicine. In our anthropologic understanding, herbs encompass true herbs (soft-tissued plants) as well as shrubs and trees (botanically, not considered herbs). Herbs can also be in the form of climbers and aquatic plants.
Herbs are frequently served as ulam or a raw salad in Southeast-Asian cuisine, such as Malay cuisine. (Photo credit: Marshall Cavendish)
Most of the world's plant species remains unknown and undescribed, but an estimated 400,000 species exist. The majority of these are found in the tropical rainforest, with the Southeast Asian rainforests thought to house about 6,500 medicinal plant species. In Malaysia, with 58.1% covered with tropical rainforests during the last century, approximately 20,000 plant species exists; of these, 10% are believed to have medicinal properties. More than 2,000 species are used in various medicinal, fragrance, agriculture and food industries.
Traditional Chinese medicine utilises the dried roots, leaves and stems of herbs. (Photo credit: Marshall Cavendish)
What give plants their medicinal properties? Plants produce both primary and secondary metabolites. The primary compounds are needed for basic functions such as photosynthesis and respiration, whereas the secondary metabolites provide colour and fragrance to flowers to draw the attention of pollinators, or produce toxins to dissuade pests. These useful secondary compounds are produced in small quantities by herbs, and essential oils can be extracted and used as flavour enhancers or perfumes.
Secondary compounds can also take the form of fatty acids, gums and resins, which are used as flavouring and incense. Some can be highly complex, and have bioactive properties - meaning they have a biological effect in humans, potentially becoming effective medicines. In fact, may compounds have been isolated and are commonly used in Western medicine.
Local herbs sold as vegetables and ulam in wet markets. (Photo credit: Marshall Cavendish)
Besides having medicinal value, many local species of herbs are eaten raw in Southeast Asian countries. These are called ulam in Malaysia, and are served raw or blanched, as a salad alongside spicy, shrimp-based sauces known as sambal.
The large global market for plant-based medicines and pharmaceuticals continues to expand, as well as the demand for other applications such as biopesticides and biofuel. Due to its multiracial and multicultural background, Malaysian traditional medicine weaves together knowledge from Ayurvedic, traditional Chinese and Malay remedies. Paired wtih the increasing global demand for alternative medicine, and its biodiversity-rich rainforest resources with unexplored potential for new bioactive compounds, Malaysia is poised to enter the market for plant-based medicines.
Health and nutritional supplements using medicinal herbs are increasing in popularity. (Photo credit: Marshall Cavendish)
Adapted from Herbs of Malaysia, written by Joseph Samy, M. Sugumaran, K.L.W. Lee and edited by K.M. Wong; published by Marshall Cavendish.