Taiwan, located in the subtropical areas, is an island where a variety of colorful and beautiful flowers can be seen growing widely in the spring-like four seasons. To continue the flower stamp series, the Directorate will issue on March 12, 1997, a set of 3 stamps featuring 3 evergreen shrubs. They are the Rhododendron x mucronatum , also known as the Rhododendron, the Hibiscus rosa-sinensis, also known as the Rose Mallow. Chinese Hibiscus, and the Hydrangea macrophylla, also known as the Big-leaf Hydrangea. The subject matter for these flower stamps, in denominations of NT$5.00, 12.00, and 19.00, was supplied by Marvin Jeng , head of the Department of Botany, Taiwan Museum.    The woody plant refers to shrubs with showy blossoms. Many flowers produced by shrubs are grown in gardens , but their main commercial importance is as potted plants, forced to flower in greenhouses. Ninety percent ol the shrubs propagated from cuttings for decoration can survive if given adequate temperature and humidity. It is delightful to watch these attractive and colorful flowers, especially during the flowering season.