Thalictrum leuconotum Franchet (1889: 15)

Zeng, You-Pai, Yuan, Qiong & Yang, Qin-Er, 2021, Thalictrum jilongense and T. tenuicaule (Ranunculaceae), described from China, are both merged with T. leuconotum, Phytotaxa 509 (2), pp. 168-184 : 172-179

publication ID	https://doi.org/ 10.11646/phytotaxa.509.2.2
persistent identifier	https://treatment.plazi.org/id/F87D87FF-FFE6-FFBB-DC90-FA75FB0DF814
treatment provided by	Marcus
scientific name	Thalictrum leuconotum Franchet (1889: 15)
status

Treatment

Thalictrum leuconotum Franchet (1889: 15) View in CoL . Figs. 1‒9 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 , 11 View FIGURE 11 .

Type:— China. Yunnan: Eryuan (previously known as Lan-kong), Lo-pin-chan (Luoping Shan), 3200 m, 25 May 1886, J.M. Delavay 2854

( lectotype P00147417 !, designated here; isolectotypes K000694044!, MPU011550 !, NAS00070702 !, NY00353658 !, P00147418 !,

P00147419 !, PE 00028254!). Fig. 3 View FIGURE 3 . = T. jilongense Wang (2017: 682) , syn. nov. Type:— CHINA. Xizang (Tibet): Gyirong (= Jilong), near Ruge Temple , in forest, 3600 m, 17 June 1972, Xizang Chinese Trad. Med .

Exped. 309 [ holotype PE00450478 !; isotypes HNWP(without barcode)!]. Fig. 1 View FIGURE 1 . = T. tenuicaule Wang (2020: 7) , syn. nov. Type:— CHINA. Sichuan: Luding, Hailuogou , near Camp no. 4, alpine meadow, 3745 m, 15 July 2018, Y. Yang et al. GGS181 (holotype

PE 02293705!; isotype PE 02293702!). Fig. 2 View FIGURE 2 .

Description:—Perennial herbs, totally glabrous. Roots fibrous. Stem 60–150 cm tall. Basal leaves persistent at anthesis. Cauline leaves 2–3-ternate; leaf blade triangular, 6–15 cm long, 6–13 cm broad; leaflets cuneate-obovate, orbicular-rhombic or orbicular, 7–18 mm long, 4.5–15 mm broad, herbaceous, base cuneate or orbicular, apex rounded, entire or shallowly 3-lobed; lobes usually entire, apex obtuse; veins flat on both surfaces; petioles 1–8 cm long, with stipules at base; stipules oblong, sheath-like, membranous, margin entire; stipels ovate, broadly ovate to orbicular, membranous, margin entire, apex obtuse. Inflorescence a terminal thyrse composed of 1‒several monochasia. Flowers bisexual, drooping. Sepals broadly ovate or broadly elliptic, 3–5 mm long, 2.5‒3.5 mm broad, purplish-green. Stamens ca. 25, 6‒ 7 mm long; filaments ca. 3.5 mm long, filiform, purplish or whitish; anthers ca. 2.5 mm long, oblong, yellow or pale brown, mucronate at apex. Carpels 1–6, occasionally absent, stipitate; stipe ca. 1 mm long; ovary compressed ellipsoid; style 1.5‒2.5 mm long, straight; stigma oblong, narrowly winged, sessile. Achenes 1‒6, 8‒ 9 mm long, drooping; stipe ca. 2.5 mm long; body lunate, ca. 6 mm long, ca. 2.5 mm broad, compressed, shallowly ribbed; style persistent, reflexed.

Phenology:—Flowering from May to July; fruiting from July to August.

Distribution and habitat:— Thalictrum leuconotum is widely distributed in Bhutan, China (western Sichuan, southeastern Xizang, northwestern Yunnan), and Nepal ( Fig. 10 View FIGURE 10 ). It grows in forests, shrubs or alpine meadows at altitudes of 2900–4100 m above sea level.

Typification:—In the protologue of Thalictrum leuconotum, Franchet (1889) cited only a single collection, i.e. J.M. Delavay 2854, from Lan-kong (now Eryuan) in northwestern Yunnan province, China. We have been able to trace eight duplicates of this collection from K, MPU, NAS, NY, P, and PE. It is worth mentioning that the collection date of the MPU sheet (barcode MPU011550) is 16 May 1886, not 25 May 1886 as given in the protologue and in other sheets. These sheets are all well preserved (except the PE sheet that has only one flower and several leaflets) and match the original description, and are therefore syntypes, as the author did not specify which one was used to prepare the original description. In conformity with ICN Art. 9.10 and Art. 9.11 ( Turland et al. 2018) and as discussed by McNeill (2014), a lectotypification is needed for T. leuconotum . In the above, the P sheet (barcode P00147417) that bears a dissection drawing has been designated as the lectotype of T. leuconotum , and the other seven sheets as isolectotypes.

Additional specimens examined:— BHUTAN. Gasa: F. Ludlow, G. Sherriff & J.H. Hicks 16557 (BM). Upper Kulong Chu: Me La, F. Ludlow, G. Sherriff & J.H. Hicks 20313 (BM, K), F. Ludlow, G. Sherriff & J.H. Hicks 20730 (BM).

CHINA. Sichuan: Barkam, C.L. Wu 32266 (PE00471178), C.L. Wu 32507 (PE01040656); Jiulong, Anonymous 151 (SM, SM704604650), Y.C. Zhu 20447 (CDBI0026210, CDBI0026211, CDBI0026212, CDBI0026309); Kangding, Z.J. Zhao, J.B. Shi & D.G. Fan 114269 (SZ00092647, SZ00092648, SZ00092649), Z.J. Zhao, J.B. Shi & D.G. Fan 114403 (SZ00092646); Lixian, S.Y. Chen, C. Ho & M.F. Zhong 5552 (SM704604948, SZ00092320), K.L. Chu 7124 (NAS, NAS00187312, NAS00187313, NAS00187314, NAS00187315, NAS00187317), C. Ho & T.L. Chow 12790 (IBSC0090613, NAS00187311, PE00471176, SZ00092319); Luding, Anonymous 1514 (CDBI0026743), K.Y. Lang, L.Q. Li & Y. Fei 244 (KUN0689915, PE01108884, PE01108885), Y. Tang, Y.H. He & P.L. Shi 297 (CDBI0026744, CDBI0026745), Q.Q. Wang & Z.A. Liu 22401 (CDBI0026208, CDBI0026209, IBSC0090197, WUK), Y.P. Zeng & Q.L. Huang 344 (IBSC), Y.P. Zeng & Q.L. Huang 357 (IBSC); Mabian, Mabian Exped. 841 (SM704604893, SM704604944); Muli, Q.S. Zhao 6604 (CDBI0026312, CDBI0026313, CDBI0026314, SZ00092642, SZ00092643, SZ00092655); Xiaojin, Sichuan Econ. Plant Exped. 135 (PE00427841, SZ00092318), F.T. Wang 21213 (PE01040630); Yanyuan, H. Handel-Mazzetti 554 (E), S. Jiang et al. 5912 (KUN0690116, PE00471179, SZ00092640, SZ00092641). Xizang: Cona, F. Ludlow & G. Sherriff 773 (BM, E), F. Ludlow, G. Sherriff & G. Taylor 5623 (BM); Mainling, F. Kingdon Ward 5788 (K), F. Ludlow, G. Sherriff & H.H. Elliot 13992 (BM); Yadong, L. Wang, X.Q. Guo & Y.P. Zeng 2952 (IBSC). Yunnan: Deqen, F. Kingdon Ward 750 (E); Eryuan, J.M. Delavay s.n. (P00147079, P00147880, P00147881), J.M. Delavay 17 (K, P00147416), J.M. Delavay 3375 (P00147877, P00147878), J.M. Delavay 3540 (P00147420), J.M. Delavay 4319 (K, P00147421, P00147422, P02383411), J.S. Yang 809 (PE00471163); Gongshan, X.H. Jin et al. DLJ-ET 1627 (PE02030480, PE02283026, PE02283027); Lijiang, R.C. Ching 20652 (KUN0689901, KUN0689902, PE00471166), R.C. Ching 30228 (KUN0689904, PE00471162, PE00471168), G. Forrest 2316 (E, K), Kunming-Edinb. Yulong-Shan Exped. 267 (E, KUN0689914), J.F. Rock 3522 (E); Lushui, Z.X. Tang 115 (PE00471463); Ninglang, F. Kingdon Ward 4121 (E); Shangri-la (previously known as Zhongdian), Alp. Gard. Soc. Exped. 542 (K), T.T. Yu 11806 (IBSC0090778, KUN0689906, KUN0689907, PE00471164, PE00471165), Zhongdian Exped.63-2810 (KUN0690336, KUN0690337), Zhongdian Exped. 63-2824 (KUN0690334, KUN0690335), Zhongdian Exped. 3629 (KUN0690655, KUN0690656); Weixi, K.M. Feng 4283 (KUN0689909, KUN0689910, KUN0689912, PE00471170).

NEPAL. Gandaki: J.D.A. Stainton, W.R. Sykes & L.H.J. Williams 1174 (BM), J.D.A. Stainton, W.R. Sykes & L.H.J. Williams 3146 (BM). Jangla Banyang, S. Einarsson, L. Skärby & B. Wetterhall 1163 (BM).

Notes:— Thalictrum leuconotum is widely distributed in Bhutan, China and Nepal ( Fig. 10 View FIGURE 10 ). The distribution of this species is continuous in the Hengduan Mountainous region in southwestern China and in the Himalayas. The type locality of T. jilongense is situated at the west edge of the distribution area of T. leuconotum , adjacent to Nepal. Some collections of Thalictrum from Bhutan and Nepal have been correctly identified as T. leuconotum ( Fig. 11 View FIGURE 11 ). Hara (1979), Grierson (1984) and Press et al. (2000) all recorded T. leuconotum to occur in the eastern Himalayan region. Yonekura (2008), however, pointed out that a collection, J.D.A. Stainton, W.R. Sykes & L.H.J. Williams 1174 ( Fig. 11C View FIGURE 11 ), from Mustang in Nepal and identified as T. leuconotum on the determination slip, differed from this species from southwestern China by its conspicuous veinlets of leaflets on the lower surface, larger stipules, and longer pedicels (1– 2 cm long), and might represent an undescribed species. In the Chinese T. leuconotum , in fact, the veinlets are indeed conspicuous on the abaxial surface ( Fig. 3B, D View FIGURE 3 ), the stipules are the same as those in the Mustang population from Nepal in size ( Figs. 3C View FIGURE 3 , 5D View FIGURE 5 , 8D View FIGURE 8 , 11C View FIGURE 11 ), and the pedicels are 1‒2 cm long at fruiting stage ( Figs. 6I View FIGURE 6 , 7B View FIGURE 7 ). We therefore consider that the Mustang population from Nepal in question should be referred to T. leuconotum .

Thalictrum leuconotum was recorded to occur in southern Qinghai (Nangqen, Yushu), China ( Anonymous 1972, 2000, Wang & Wang 1979, Wang 1980, 1982, 1993a, 2000a, b, 2018, Zhou 1997, Fu & Zhu 2001, Wu 2008, Xie et al. 2016). We have traced six Qinghai sheets which were identified as T. leuconotum (four sheets shown in Figure 12 View FIGURE 12 ). We determined that all these specimens should belong to T. rutifolium Hooker & Thomson (1855: 14) , a species widely distributed in Bhutan, China (Gansu, Qinghai, Sichuan, Xinjiang, Xizang, Yunnan), India, Nepal, and Pakistan. All the specimens are at the early stage of blooming, with roots robust and less numerous (3‒5 per individual), leaflets rather small (3‒5 mm long and 2‒3 mm broad), sepals ca. 1.5 mm long, ca. 1 mm broad, and stamens less than 4 mm long. Morphologically, T. rutifolium is indeed somewhat similar to T. leuconotum in habit and achene number and morphology, but differs by its roots less than 10 in number, robust or even tuberose (vs. numerous and fibrous), leaflets smaller (3‒10 mm long, 2‒7 mm broad vs. 7‒18 mm long, 4.5‒15 mm broad), sepals smaller (1.5‒3 mm long, 1‒1.5 mm broad vs. 3‒5 mm long, 2.5‒3.5 mm broad), stamens shorter (2‒4.5 vs. 6‒7 mm long), and achenes smaller (4‒6 mm long, 1.8‒2 mm broad vs. 8‒9 mm long, ca. 2.5 mm broad) ( Wang & Wang 1979, Wang 2018). These morphological differences have also been confirmed by our observations on living plants in the wild of these two species ( Figs. 5 View FIGURE 5 , 6 View FIGURE 6 , 8 View FIGURE 8 , 13 View FIGURE 13 ). Thalictrum leuconotum should therefore be excluded from the flora of Qinghai.

Thalictrum sinomacrostigma Wang (1993b: 213) View in CoL was once treated, under the name of T. macrostigma Finet & Gagnepain (1906: 125) View in CoL , as a synonym of T. leuconotum View in CoL by Wang (1980). Fu & Zhu (2001) accepted this treatment but Wang (1993b) reinstated its status as an independent species, a treatment accepted by Wang (2018) and Zeng et al. (2020). Thalictrum mairei Léveillé (1909: 339) View in CoL had previously long been placed in synonymy with T. leuconotum View in CoL ( Wang & Wang 1979, Wang 1980, 2000a, 2018, Wu 1984, Anonymous 2000, Fu & Zhu 2001). Recently Zeng et al. (2020) clarified its identity and treated it as a synonym of T. foliolosum Candolle (1818: 175) View in CoL .