267 Gardens' Bulletin Singapore 71 (2): 267–319. 2019 doi: 10.26492/gbs71(2).2019-02 Progress on Southeast Asia’s Flora projects D.J. Middleton 1 , K. Armstrong 2 , Y. Baba 3 , H. Balslev 4 , K. Chayamarit 5 , R.C.K. Chung 6 , B.J. Conn 7 , E.S. Fernando 8 , K. Fujikawa 9 , R. Kiew 6 , H.T. Luu 10 , Mu Mu Aung 11 , M.F. Newman 12 , S. Tagane 13 , N. Tanaka 14 , D.C. Thomas 1 , T.B. Tran 15 , T.M.A. Utteridge 16 , P.C. van Welzen 17 , D. Widyatmoko 18 , T. Yahara 14 & K.M. Wong 1 1 Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, 259569 Singapore david_middleton@nparks.gov.sg 2 New York Botanical Garden, 2900 Southern Boulevard, Bronx, New York, 10458, USA 3 Auckland War Memorial Museum Tāmaki Paenga Hira, Private Bag 92018, Auckland 1142, New Zealand 4 Ecoinformatics and Biodiversity, Department of Bioscience, Aarhus University Building 1540, Ny Munkegade 114, Aarhus C DK 8000, Denmark 5 The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, 61 Phahonyothin Rd., Chatuchak, Bangkok 10900, Thailand 6 Herbarium, Forest Research Institute Malaysia, Kepong, Selangor 52109, Malaysia 7 School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia 8 Department of Forest Biological Sciences, College of Forestry & Natural Resources, University of the Philippines - Los Baños, College, 4031 Laguna, Philippines 9 Kochi Prefectural Makino Botanical Garden, 4200-6 Godaisan, Kochi, 7818125, Japan 10 Southern Institute of Ecology, Vietnam Academy of Science and Technology, 01 Mac Dinh Chi Street, District 1, Ho Chi Minh City, Vietnam 11 Forest Research Institute, Forest Department, Ministry of Natural Resources and Environmental Conservation, Yezin, Nay Pyi Taw, Myanmar 12 Herbarium, Royal Botanic Garden Edinburgh, Edinburgh EH3 5LR, Scotland 13 Kagoshima University Museum, Kagohshima University, 1-21-30 Korimoto, Kagoshima, 890-0065, Japan 14 Department of Botany, National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki 305-0005, Japan 15 Herbarium, Botany Department, Institute of Ecology and Biological Resources (IEBR), Vietnam Academy of Science and Technology (VAST), 18. Hoang Quoc Viet Street, Nghia Do, Cau Giay, Hanoi, Vietnam 16 Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, UK 17 Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, Netherlands 18 Indonesian Institute of Sciences (LIPI), Kebun Raya Bogor, Jl. Ir. H. Juanda 13, Bogor, Jawa Barat 16122, Indonesia ABSTRACT. Southeast Asia (Myanmar, Thailand, Cambodia, Laos, Vietnam, Malaysia, Singapore, Brunei Darussalam, Indonesia, Timor Leste, the Philippines and Papua New Guinea) is a region of high plant diversity with an estimated 50,000 fowering plant species. Estimates of plant diversity in the region continue to grow as large numbers of new species are described even though there have been suggestions that there are few new species to be