To promote the protection of natural resources, this Directorate released sixteen Taiwan Plant Stamps in 1991. They depict sixteen endemic plants peculiar to Taiwan. The stamps are divided into four issues, to be released in spring, summer, autumn, and winter. First Issue 2.00 Petasites formosanus 3.00 Heloniopsis acutifolia 7.50 Disporum shimadai 9.00 Viola nagasawai Second Issue 2.00 Gaultheria itoana 3.00 Lysionotus montanus 7.50 Leontopodium microphyllum 9.00 Gentiana flavo-maculata Third Issue 3.50 Rosa transmorrisonensis 5.00 Impatiens devolii 9.00 Impatiens uniflora 12.00 Impatiens tayemonii Fourth Issue 3.50 Kalanchoe garambiensis 5.00 Pieris taiwanensis 9.00 Pleione formosana 12.00 Elaeagnus oldhamii