A taxonomic synopsis of Heliotropiaceae and new combinations in Heliotropium from Thailand Author Rueangsawang, Kanokorn https://orcid.org/0000-0003-1595-1514 Department of Biology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240, Thailand Author Chantaranothai, Pranom https://orcid.org/0000-0002-5065-6169 Applied Taxonomic Research Center, Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand & Royal Botanic Gardens, Kew, Richmond, Surrey TW 9 3 AE, UK pranom@kku.ac.th text PhytoKeys 2023 2023-09-21 232 189 210 http://dx.doi.org/10.3897/phytokeys.232.103647 journal article http://dx.doi.org/10.3897/phytokeys.232.103647 1314-2003-232-189 650B1993F8DC52FBBF49899A6B6A4D6F 5. Euploca strigosa (Willd.) Diane & Hilger, Bot. Jahrb. Syst. 125(1): 49. 2003. Fig. 3D-F Heliotropium strigosum Willd., Sp. Pl., ed. 4, 1(2): 743. 1798. Type: Ghana [Guinea], Isert s.n. (holotype B [B-W 219/3253, microfiche], isotypes C [C10003972!], P [P-JU6571 image!]). Lithospermum chinense Hook. & Arn., Bot. Beechey Voy.: 202. 1837. Type: China, Canton, Vachell 286 (holotype E [E00369167!]; isotype BR [BR0000006966485 image!]). Type . Based on Heliotropium strigosum Willd. Distribution. Africa, Afghanistan, Pakistan, India, Nepal, Bhutan, Myanmar, Laos, Cambodia, Vietnam, China (Hainan, Kwangtung), Thailand (Fig. 1E ), Malesia, Australia. Ecology. Open area of bare rock in dry dipterocarp and dry open deciduous forests; 50-400 m alt., flowering and fruiting from April to November. Specimens examined. Thailand , North-eastern : Sakon Nakhon , Phu Phan NP , 400 m alt., 6 Aug 2004 , Nielsen et al. 1542 (BKF); Phrae , Ban Nun, Song, 193 m alt., 25 June 2012 , Norsaengsri & Tathana 9480 (QBG). Eastern: Surin , Nadi, 17 May 1965 , Sakol 224 (BK); Ubon Ratchathani , Chiet, 100 m alt., 21 May 1932 , Kerr 21537 (BK, BM, E, K). Central: Chai Nat , Utapao, 20 Sept 1930 , Kerr 19692 (ABD, BM, BK). South-western: Kanchanaburi , 5 km west of Thong Pha Phum Town , 16 Oct 2015 , Tanming 873 (QBG); Thong Pha Phum, along route 323, 4 km , 240 m alt., 29 Nov 1982 , Koyama et al. T-30469 (BKF); Prachinburi , Watananakorn, 23 July 1987 , Paisooksantivatana & Sangkhachand 2109-87 (BK). South-eastern: Sa Kaeo , Aranyaprathet, 50 m alt., 3 Apr 1930 , Kerr 19575 (BM, BK, K). Peninsular: Songkhla , Padang Besar, 50 m alt., 24 Dec 1927 , Kerr 13602 (BM, BK, K) . Diagnostic characters. Euploca strigosa is most similar to E. paniculata in having spike-like inflorescences arranged in one rank that can elongate up to 10 cm long, but it differs in the stem being a prostrate to many-branched (vs. erect unbranched to few-branched stem in E. paniculata ), the narrowly elliptic leaves with strigose hairs on both surfaces, 5-10 x ca. 3 mm (vs. linear leaves with greyish tomentose hairs, 7-40 x 1-2 mm in E. paniculata ).