Heliotropium montanum (Lour.) Rueangs. & Chantar., 2023

Rueangsawang, Kanokorn & Chantaranothai, Pranom, 2023, A taxonomic synopsis of Heliotropiaceae and new combinations in Heliotropium from Thailand, PhytoKeys 232, pp. 189-210 : 189

6. Heliotropium montanum (Lour.) Rueangs. & Chantar. comb. nov.

Fig. 5B

Tournefortia montana Lour., Fl. Cochinch. 1: 122. 1790.

Messerschmidia montana (Lour.) Roem. & Schult. Syst. Veg., ed. 15 bis 4: 544. 1819.

Tournefortia sampsonii Hance, J. Bot. 6: 330. 1868. Type: China, Sai-chii-shan, Cantonesis, Sampson 13035 (holotype BM [BM001014454!]).

Tournefortia boniana Gagnep., Notul. Syst. (Paris) 3: 33. 1914. Type: Vietnam, Tonkin mèridional, Bon 1932, (lectotype, designated here: P [P03897617 image!]; isolectotypes: P [P03897616 image!], K [K000998141!]).

Tournefortia gaudichaudii Gagnep., Notul. Syst. (Paris) 3: 34. 1914. Type: Vietnam, Cochinchine: Tourane, Gaudichaud 180 (lectotype, designated here: P [P03897604 image!]; isolectotypes: P [P03897602 image!], K [K000998140!]).

Tournefortia brachyantha Merr. & Chun, Sunyatsenia 2: 314. 1935. Type: China, Jiangsu, Hainan, How70424 (holotype K [K000998121!]).

Type.

Vietnam, Cochinchine: Tourane, Gaudichaud 180 (neotype, designated here: P [P03897604 image!]; isoneotypes: P [P03897602 image!], K [K000998140!]).

Distribution.

India (Assam), Bangladesh, southern China, Myanmar, Laos, Vietnam, Cambodia, Thailand (Fig. 1K ).

Ecology.

Open roadside, along the streams in evergreen forest, bamboo forest, slopes of the hills in evergreen forest and mixed deciduous forests, 250-1,500 m alt., flowering and fruiting from February to December.

Specimens examined.

Thailand, Northern: Chiang Rai, Mae Chan, 450 m alt., 17 Mar 2005, Pooma et al. 4859 (BKF); Chiang Mai, Mae Hia Thai Literary Botanical Garden, 350 m alt., 13 June 2003, TLBG 165 (QBG); 300 m alt., 21 Jan 1921, Kerr 4692 (BM, BK, K); Nan [Doi Phu Kha NP 1,500 m alt., 24 Jan 2003, Srisanga 2684 (QBG); ibid., 11 Apr 2002, Srisanga 1253 (QBG); ibid., 1,200 m alt., 19 Mar 2000, Srisanga 1340 (BKF, QBG); Ban Den Thara, Pra That, Chiang Klang District, 346 m alt., 15 Mar 2018, Khattiyot et al. 616 (QBG); Tam Paa Toop, Ta Wang Paa, 10 km from Nan, 360 m alt., 24 Feb 1998, Srisanga et al. 220 (QBG); Lampang, Doi Luang NP, Wahng Gaye waterfall, 625 m alt., 26 Mar 1997, Maxwell 97-753 (BKF); Uttaradit, Phu Soi Dao NP, 1,000 m alt., 18 Mar 2002, Chamchumroon & Puff V.C.1438 (BKF); Tak, Doi Muser, Hui Sakulee, 700 m alt. 27 Feb 1987, Paisooksantivatana Y2032-87 (BK); Mae Sot to Mae Sariang, 19 Jan 1995, Pooma 1007 (BKF, CMUB). South-western: Uthai Thani, Ban Rai, 4 Mar 1977, Sutheesorn 4017 (BK); Kanchanaburi, Sangkhla Buri to Thong Pha Phum, 180 m alt., 17 Dec 2009, Pooma et al. 7436 (BKF); Sai Yok, Khwae Noi, 21 Dec 1961, Larsen 8893 (BKF, C, K); ibid., 21 Dec 1961, Simitnand 9500 (BKF); Sai Yok, 23 Dec 1961, Larsen 8916 (C); Pompee Village near Khwae Noi, 250 m alt., 26 Mar 1968, van Beusekom & Phengklai 129 (BKF, E, K, L); Mae Nam Noi near waterfall, 2 Jan 1962, Phengklai 398 (BKF); Huai Banlcae, 8 Nov 1971, van Beusekom et al. 3528 (BKF); Thong Pha Phum NP, 260 m alt., 3 Dec 2003, Sirimongkol 69-2 (BKF). Peninsular: Krabi, Ban Nai Chong, 17 Dec 1965, Umpai 208 (BK); Khap Thong Thai, 19 Jan 1966, Hansen & Smitinand 12002 (BKF, C); Nakhon Si Thammarat, Nop Phitum, 80 m alt., 13 Feb 2005, Williams et al. 1475 (BKF, E).

Diagnostic characters.

Heliotropium montanum can be recognised by ovate-lanceolate leaves, glabrous to glabrescent on both surfaces and minute tubercules on the lower surface, loosely dichotomous branched inflorescences and glabrous flowers. The specimens from Thailand have mostly been misidentified as H. intonsum . These two species can be differentiated by leaf shape, the type of indument on each of the inflorescences and corollas that are glabrous ( H. montanum ) or densely greyish tomentose hairs ( H. intonsum ).

In the original description of T. montana Loureiro (1790) described from ' Cochinchina tributarii ', the type collection of Loureior has not been found in either P or BM. Therefore, this species is represented by specimens of Gaudichaud 180 (K000998140, P03897604, P03897602) from ' Cochinchine: Tourane ', Loureiro’s initial locality. The specimen at P [P03897604] is designated here as a neotype for T. montana because it is in the best condition and the characters match the original description.

In the protologue, Gagnepain (1914) described T. boniana , based on two different collections (Bon 1357 & Bon 1932). Bon 1932 P [P03897617] is chosen as the lectotype because it is best preserved, with complete inflorescences and numerous flowers and has two duplicates.

Gagnepain (1914) did not specify which of the duplicates of T. gaudichaudii was the holotype; therefore, the specimen at P [P03897604] is designated as the lectotype because it is a perfect match for the description in the protologue.

Figures

Figure 1. Distribution of Heliotropiaceae from Thailand, based on the specimens examined.

Figure 5. Species of Heliotropium from Thailand A H. intonsum (Kerr) Rueangs. & Chantar. B H. montanum (Lour.) Rueangs. & Chantar. Photos by Kanokorn Rueangsawang.