Thai Forest Bulletin (Botany) <p>Thai Forest Bulletin (Botany)&nbsp;- here referred to as TFB (Botany) -&nbsp;was first published in 1954 by the Royal Forest Department, under the leadership of its first editor Prof. Dr. Tem Smitinand. In 2002, the journal was published by the Department of National Parks, Wildlife and Plant Conservation with Prof. Dr. Thawatchai Santisuk as editor, supported by editorial board members from several prominent herbaria in Europe. At present, the TFB (Botany) is published by the Forest Herbarium in Bangkok, with Dr. Rachun Pooma and Dr. Tim Utteridge as editors. The journal is published once a year, usually in September-December with the manuscript no submission deadline, and articles are published in English. All manuscripts are peer reviewed by international scientists and edited by native English language speakers on the editorial board before acceptance and publication.&nbsp;TFB (Botany) will become both printed and electronic journal starting with volume 44 (2016), and through the TFB (Botany) Archive, every article published since 1954 is available and completely searchable online.</p> <p>ISSN : 0495-3843&nbsp;(print), 2465-423x (electronic)</p> Forest Herbarium (BKF) en-US Thai Forest Bulletin (Botany) 0495-3843 Two new species of Pittosporum (Pittosporaceae) for the Flora of Thailand <p>Two new species of <em>Pittosporum </em>(Pittosporaceae) are reported for Thailand. <em>Pittosporum lacrymasepalum </em>from Trat Province and <em>P. maxwellii </em>from Doi Inthanon, Chiang Mai Province are described and illustrated.</p> Timothy M.A. Utteridge Copyright (c) 2020 Forest Herbarium 2020-07-09 2020-07-09 48 2 87 94 10.20531/tfb.2020.48.2.01 Psammosilene tunicoides (Caryophyllaceae) a new generic and species record for Thailand <p><em>Psammosilene tunicoides</em>, a new generic and species record for Thailand, is reported. The new record was discovered on a degraded calcareous substrate mountain in the western part of Thailand near the Thai-Myanmar border. The species was previously reported to be endemic to SW China. This occurrence in Thailand greatly extends the distribution of the species. A lectotype is designated here.</p> Somran Suddee Thamarat Phutthai Naiyana Tetsana Theerawat Thananthaisong Wittawat Kiewbang Copyright (c) 2020 Forest Herbarium 2020-07-13 2020-07-13 48 2 95 100 10.20531/tfb.2020.48.2.02 New records of the genus Psychotria (Rubiaceae) from Thailand <p>Four species of <em>Psychotria</em> are newly recorded from Thailand: <em>P. bonii</em>, <em>P. griffithii</em>, <em>P. langbianensis</em> and <em>P. pachyphylla</em>. Descriptions and list of synonyms are provided and a lectotype for <em>P. bonii</em> is designated.</p> Teerawat Srisuk Voradol Chamchumroon Pimwadee Pornpongrungrueng Copyright (c) 2020 Forest Herbarium 2020-07-15 2020-07-15 48 2 101 107 10.20531/tfb.2020.48.2.03 Begonia colliculata (Begoniaceae), a new species from Nam Kading National Protected Area, Bolikhamxai province, Laos <p><em>Begonia colliculata</em> is described and illustrated with photographs from Nam Kading National Protected Area, in the Bolikhamxai Province of Laos.</p> Keooudone Souvannakhoummane Soulivanh Lanorsavanh Jeong Ho Park Ho Sang Kang Tai Hyeon Ahn Singkone Xayalath Chanhsamone Phongoudom Copyright (c) 2020 Forest Herbarium 2020-07-24 2020-07-24 48 2 108 113 10.20531/tfb.2020.48.2.04 Heterostemma brownii (Apocynaceae), a new record for Laos and Thailand <p><em>Heterostemma brownii</em> is reported as a new record for the floras of Laos and Thailand. A lectotype is also designated for the name <em>H. brownii</em>. A description based on Thai and Laos collections, photographs and notes are provided.</p> Woranart Thammarong Sarayut Rakarcha Michele Rodda Copyright (c) 2020 Forest Herbarium 2020-07-30 2020-07-30 48 2 114 117 10.20531/tfb.2020.48.2.05 The Cenozoic leaf morphotypes and palaeoclimate interpretation from the Doi Ton Formation, Mae Sot District, Tak Province, western Thailand <p>The Cenozoic palaeovegetation and palaeoclimate of Doi Ton, western Thailand, megaflora are reconstructed based on physiognomic climate analysis, including Leaf Margin Analysis (LMA), Leaf Area Analysis (LAA), Leaf Size Index (LSI), Climate Leaf Analysis Multivariate Program (CLAMP), and systematic descriptions of each leaf morphotype. The leaf fossils were divided into 23 dicotyledonous leaf morphotypes and two unknown leaf morphotypes. The mean annual temperature results from LMA indicate 32.3 ± 1.17 °C and CLAMP shows 21.2°C. CLAMP also provides temperature data of a warm month mean temperature (WMMT) of 27.4 °C and a CMMT of 14.2 °C, which is similar to the present climate. The mean annual precipitation is estimated by LAA to be ~ 125 cm. CLAMP suggests precipitation in the 11 months of growing period was 154.9 cm with the three wettest months having precipitation of 73 cm, widely contrasting with 15.5 cm for the three driest months. The precipitation shows the signal of the monsoon effect. The temperature, precipitation, and LSI mirrored the vegetation of the contemporary Doi Ton area which is a semi-evergreen forest in the tropical zone. The palaeoclimatic parameters of Doi Ton are in good agreement with those of south China and northwest<br>India from the Eocene period and the present-day Mae Sot area. Moreover, the Doi Ton flora also closely matches the humid subtropical modern vegetation of south China. Palaeoclimate and vegetation analysis support an Eocene age estimate for the Doi Ton Formation however further independent age estimates are required to test this working hypothesis.</p> Atiwut Bunlam Yupa Thasod Pitaksit Ditbanjong Rattanaporn Fongngern Paul J. Grote Copyright (c) 2020 Forest Herbarium 2020-08-03 2020-08-03 48 2 118 141 10.20531/tfb.2020.48.2.06