Cynanchum thesioides (Freyn) K. Schum. in Engl. & Prantl, Nat. Pflanzenfam. 4 (2): 252 (1895).

Zhang, Cai-Fei, Zhang, Dong-Juan, Liao, Miao & Hu, Guang-Wan, 2023, A taxonomic revision of Cynanchum thesioides (Apocynaceae) with two new synonyms, PhytoKeys 219, pp. 11-25 : 11

Cynanchum thesioides (Freyn) K. Schum. in Engl. & Prantl, Nat. Pflanzenfam. 4 (2): 252 (1895).

Vincetoxicum thesioides ≡ Vincetoxicum thesioides Freyn, Oesterr. Bot. Z. 40: 124 (1890) ≡ Cynanchum sibiricum var. thesioides (Freyn) Kom., Trudy Imp. S.-Peterburgsk. Bot. Sada 25(1): 282 (1905) - Holotype: Russia, wüste Orte um Nerczynsk, July-Aug. 1888, K.F. Karo 127 (BRNM [15481/36], ex herb. J. Freyn) - Fig. 2A .

Asclepias sibirica = Asclepias sibirica L., Sp. Pl.: 217 (1753) ≡ Cynanchum sibiricum (L.) R. Br., Mem. Wern. Nat. Hist. Soc. 1: 48 (1811), nom. illeg., non Willd. (1799). ≡ Vincetoxicum sibiricum (L.) Decne. in DC, Prodr. 8: 525 (1844) ≡ Vincetoxicum sibiricum var. boreale Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg 23: 355 (Mar 1877), nom. illeg., as ' borealis ', ≡ Cynanchum sibiricum var. boreale (Maxim.) Kom., Trudy Imp. S.-Peterburg sk. Bot. Sada 25(1): 281 (1905), nom. illeg. ≡ Antitoxicum sibiricum (L.) Pobed., Fl. USSR 18: 707-708, pl. 38: 1 (1952) ≡ Alexitoxicon sibiricum (L.) Pobed., Taxon 11: 174 (1962) ≡ Rhodostegiella sibirica (L.) C.Y. Wu & D.Z. Li, Acta Phytotax. Sin. 28(6): 466 (1990) - Lectotype (designated by Grubov [2000: 138]): Russia, Siberia, Gmelin s.n., Herb. Linn. No. 310.35 (LINN; image available at https://linnean-online.org/2155/ and https://plants.jstor.org/stable/10.5555/al.ap.specimen.linn-hl310-35).

Vincetoxicum sibiricum australe = Vincetoxicum sibiricum var. australe Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg 23: 355 (Mar. 1877), " australem " ≡ Cynanchum sibiricum R. Br. var. australe (Maxim.) Kom., Trudy Imp. S.-Peterburgsk. Bot. Sada 25(1): 292 (1905). ≡ Cynanchum thesioides var. australe (Maxim.) Y. Tsiang & P.T. Li, Acta Phytotax. Sin. 12: 101 (1974) ≡ Rhodostegiella sibirica var. australis (Maxim.) C.Y. Wu & D.Z. Li, Acta Phytotax. Sin. 28: 466 (1990) - Lectotype (designated here): China. Nei Mongol, "Mongolia occidentalis, Terra Ordos, valle fl. Hoang-ho", 24 Jul - 5 Aug 1871 (fl.), N.M. Przewalsky 298 (LE [LE01036690]); isolectotypes: K [000872724], LE [LE01036688, LE01036689], P [P03872677] - Fig. 2B .

Vincetoxicum sibiricum linearifolium = Vincetoxicum sibiricum f. linearifolium Debeaux, Actes Soc. Linn. Bordeaux 31(4): 235 (1877), " linearifolia ", syn. nov. - Lectotype (designated here): China, Shandong Prov., Yantai City, “Tchéfou dunes", [1860], O. Debeaux 79 (P [P03872669], ex herb. O. Debeaux) - Fig. 2C .

Cynanchum sibiricum gracilentum = Cynanchum sibiricum var. gracilentum Nakai & Kitag., Rep. First Sci. Exped. Manch. sect. 4, 1: 43 (1934). ≡ Vincetoxicm sibiricum var. gracilentum (Nakai & Kitag.) Kitag., Rep. Inst. Sci. Res. Manchoukuo 4(7): 85 (1940) - Holotype: China, Hebei Prov., Chengde, 19 Aug 1933 (fl.), T. Nakai, M. Honda & M. Kitagawa s.n. (TI [TI00204077]) - Suppl. material 2.

Cynanchum sibiricum gracilentum hypopsilum = Cynanchum sibiricum var. gracilentum Nakai & Kitag. f. hypopsilum Nakai & Kitag., Rep. First Sci. Exped. Manch., sect. 4, 1: 43 (1934) ≡ Vincetoxicm sibiricum f. hypopsilum (Nakai & Kitag.) Kitag., Rep. Inst. Sci. Res. Manchoukuo 4(7): 85 (1940) - Holotype: China, Hebei Prov., Chengde, 19 Aug 1933 (fl. & fr.), T. Nakai, M. Honda & M. Kitagawa s.n. (TI [TI00204078]) - Suppl. material 3.

Cynanchum sibiricum latifolium = Cynanchum sibiricum var. latifolium Kitag., Rep. First Sci. Exped. Manch. sect. 4, 4: 90, (1936) ≡ Cynanchum sibiricum var. australe f. latifolium (Kitag.) Kitag., Lineam. Fl. Mansh. 363 (1939) ≡ Vincetoxicm sibiricum f. latifolium (Kitag.) Kitag., Rep. Inst. Sci. Res. Manchoukuo 4(7): 85 (1940) - Holotype: China, Liaoning Prov., Dalian, Lingshui, Lingshui Temple, 15 Aug 1930 (fl.), M. Kitagawa s.n. (TI [TI00204080]) - Suppl. material 4.

Cynanchum gobicum = Cynanchum gobicum Grubov, Novosti Sist. Vyssh. Rast. 32: 135 (2000), non C. lanceolatum Poir. (1811), syn. nov. ≡ Antitoxicum lanceolatum Grubov, Bot. Mater. Gerb. Bot. Inst. Komarova Akad. Nauk S.S.S.R. (Leningrad) 17: 21 (1955) ≡ Vincetoxicum lanceolatum (Grubov) Grubov, Novosti Sist. Vyssh. Rast. 21: 208 (1984) - Holotype: Mongolia, Dzun-Saikhan mountains, commencement of northern trail along the road from Dalan-Dzadagad to pass through Gurban-Saikhan, 22 Jul 1943 (fl.), A. Yunatov 12902 (LE [LE01036905]) - Fig. 2D .

Description.

Perennial suffrutescent sometimes lianescent herbs, usually densely shortly pubescent throughout, with white latex, arising from monopodial slightly woody creeping slender brown rhizome up to 3 m × 3 mm, with wiry horizontal offshoots. Stem and branches straight or twining above, green to dark purple; when straight 10-40 cm long, erect or ascending, simple or much divaricately branched from base, with internodes 2-30 mm long; when twining up to 2 m long, little branched, with internodes 4-8 cm long. Leaves opposite or sometimes subopposite, rarely 3- or 4-whorled, with petioles 0.5-10 (-12) mm long or subsessile; blade green, thin, linear, narrowly lanceolate, oblong-lanceolate or occasionally broadly lanceolate, 2-10.5 × 0.1-2 (-2.3) cm, apex shortly acute, obtuse or acuminate, rarely rounded, base slightly oblique, attenuate, cuneate, truncate or rounded, with colleters at middle of leaf base, margins entire, ciliolate, often revolute; mid-vein elevated abaxially, lateral veins obscure; both surfaces densely pubescent, sometimes glabrate, except the mid-veins on lower surface. Inflorescences alongside the leaf axils to terminal, with 1-10 fragrant flowers, shortly umbel- to raceme-like; peduncles 1-10 (-50) × 0.5-1.5 mm, puberulent; pedicels 1.2-10 × 0.2-0.6 mm, puberulent. Sepals ± half length of corolla, oblong, triangular or lanceolate, 1-2.8 × 0.3-0.8 mm, puberulent, ciliate, apex obtuse, acute or acuminate. Corolla white or greenish-white to yellow, 3-5 × 3-8 mm, usually glabrous, sometimes sparsely puberulent on dorsal surface and inside tube, rarely densely puberulent on both surfaces; tube 0.5-1.5 mm long; lobes 4.3-5.2 × 0.8-1.5 mm, narrowly triangular, lanceolate, oblong or oblong-ovate, apically twisted clockwise, apex ± acute or obtuse, sometimes retuse. Corona of 5 slightly fleshy lobes partly fused at bases, cupular, 0.8-1.8 mm long, shorter or longer than gynostegium; tube shorter than anthers, 0.3-0.7 mm long; lobes oval, triangular-lanceolate to linear, apices erect or incurved, acute, acuminate, obtuse or rounded, 0.5-1.4 mm long, sinuses between theses each with or without a minute triangular tooth. Follicles paired or single, ovoid-fusiform, ventricose, 4-10 × 0.8-2.5 cm, apex obtuse or attenuated, smooth or colliculate, puberulent; seeds reddish-brown, 5-10 × 3-5 mm, with white coma 1-2.4 cm long attached to micropylar end - Figs 3 - 5 .

Vernacular names.

Chinese: 地梢瓜 ( dì shāo guā); Mongolian: Sibir temeen khukh; Korean: 양반풀 (Yang-ban-pul); Russian: Ластовень сибирский (Siberian Lastoven).

Distribution.

China, Kazakhstan, North Korea, South Korea, Mongolia, Russia - Fig. 1 .

Habitat.

Thickets and/or grasses on mountain-slopes, dry valleys, sand-dunes, grasslands, roadsides, flood plains, river banks, farm land; 0-3200 m alt. - Fig. 3 .

Phenology.

Flowering March-September; fruiting June-October.

Notes.

In some online databases, such as World Flora Online (WFO 2022), Plants of the World Online (POWO 2022), the ‘accepted’ name is Vincetoxicum sibiricum (L.) Decne. This is incorrect because phylogenetic studies confirmed this species is a member of Cynanchum and far from Vincetoxicum ( Khanum et al. 2016; Hu et al. 2020; Kang et al. 2021). In addition, many online databases ( Freiberg et al. 2020; Hassler 2022; POWO 2022; WFO 2022; WCVP 2022) give C. longifolium Decne. and/or C. sibiricum Willd. var. triangularilobatum Rassulova & B.A. Sharipova as synonyms of C. thesioides . They should be excluded because their types have cordate leaves and they, therefore, belong to Cynanchum acutum subsp. sibiricum (Willd.) K.H. Rech. ( Tsiang and Li 1977; Rasulova and Sharipova 1984).

Freyn (1890) based V. thesioides on Ferdinand K. Karo 127 with flowers and young fruits collected during July and August 1888 from desert places around Nerczynsk. Although Freyn did not give a direct indication of the herbarium, he had seen three sets of Karo’s specimens ( Freyn 1889: 356): the first set kept in his private herbarium which was purchased in 1905 by the Moravian Museum in Brno (BRNM, Sutorý 2012); the second set kept by Ladislav Josef Čelakovský in the National Museum in Prague (PR); the last set kept by Josef Emmanuel Kabát which is now also kept at PR ( Stafleu and Cowan 1979: 482). The only specimen bearing the number 127 is that in BRNM (Fig. 2A ) and is, thus, the holotype of V. thesioides . Another two specimens in PR (PR793598, PR793599) collected by Karo do not have the number 127 on them, but were also annotated by Freyn as Vincetoxicum thesioides . They may be isotypes, but equally, they may have been other gatherings made by Karo on different dates or in another place near Nerczynsk. Consequently, they are not considered here to be isotypes.

Maximowicz (1877) mentioned in the protologue of V. sibiricum var. australe a collection by N.M. Przewalsky from the Ordos land towards the Yellow River ( “Hoang-ho”) in Nei Mongol, China and a collection(s) from Beijing without any further information. We have selected Przewalsky’s specimen at LE as the lectotype following unpublished annotations by N. Imkhanitzkaya (Fig. 2B ).

In the protologue of Vincetoxicum sibiricum f. linearifolium Debeaux, specimens collected by Debeaux from "sables maritimes de la presqu’ile de Yan-tai" and "dunes de Fou-chan-yen" with flowers on 14 July and fruits on 23 August [1860] were cited. We have found five sheets of Debeaux’s specimens at P. Of these, one sheet with flowering plants (barcode P03872669) and fruiting plants (barcode P00877371) was annotated by Debeaux as " Vincetoxicum sibiribicum Dec. forma foliis augustioribus ". We designate the flowering plants from this sheet as the lectotype (Fig. 2C ).

Selected specimens examined.

China: Beijing, C.F. Zhang 5588 (HIB) ; Shandong, C.Y. Chiao 2878 (E, IBK, IBSC, NAS, PE) ; Shaanxi, Y.W. Tsui 10389 (CDBI, KUN, PE) ; Sichuan, Guangyuan Exped. 6001 (SM) ; Xinjiang, G.L. Zhu et al. 6689 (NAS, PE, WUK). Kazakhstan: Lake Zaysan , Anonymous s.n. (E, P) . North Korea: Pyongyang, Pyongyang Bot. Garden s.n. (PE [01572927]); Nampo, U. Faurie 736 (P). Mongolia : Arkhangai, I.A.Gubanov 341 (MW) ; Dornod, I.A. Gubanov 5729 (MW) ; Dornogovi, I.A. Gubanov 5196 (MW); Govisümber, G.N. Ogureeva s.n. (MW) ; Khentii, I.A. Gubanov 10122 (MW). Russia: Far East . Amur, E. Boyko & V. Starchenko s.n. (RSA [RSA0286750]); Zabaykalsky, F.K. Karo 359 (E, P, WIS). Siberia . Altai Republic, T.S. Elias et al. 4394 (NY, PE, RSA) ; Irkutsk, H.H. Iltis et al. 252 (NY, WIS) ; Tuva, V.V. Nikitin et al. 1268(2) (PE) [For a full specimens examined see Suppl. material 1] .

Figures

Figure 1. Distribution map of Cynanchum thesioides in north-eastern Asia. The base map was downloaded from the Microsoft Bing Satellite Map via QGIS 3.26 (https: // qgis. org /). Map data 2022 (C) Microsoft.

Figure 2. Type specimens A holotype of Cynanchum thesioides (BRNM [15481 / 36 ]]) B lectotype of Vincetoxicum sibiricum var. australe (LE [LE 01036690]) C lectotype of Vincetoxicum sibiricum. Vincetoxicum sibiricum f. linearifolium (flowering plants, P [P 03872669]), with fruiting plants (syntype, P [P 00877371]) mounted on the same sheet: D holotype of Antitoxicum lanceolatum (LE [LE 01036905]).

Figure 3. Cynanchum thesioides A erect plant growing in desert B scandent plant climbing a stony wall C erect plant growing on mountain slope D prostrate plant on roadside wasteland A by Xin-Xin Zhu in Xilinhot, Nei Mongol B, D by Lei Xie in Beijing C from C. F. Zhang 5588 (HIB) and photographed by Cai-Fei Zhang in Beijing.

Figure 5. Cynanchum thesioides A corona and gynostegium with long style-head (front view) B corona and gynostegium with short style-head (front view) C corona and gynostegium with short style-head (vertical view) D corona and gynostegium with long style-head (vertical view) E pair of fruits F stamen (front view) G stamen (back view) H stamen (front view) I stamen (back view) J pollinarium K seeds the concave surface (left) and convex surface (right) A, D, F, G and J from Meng Wei in C. F. Zhang 6791 (HIB); B, C, H, I from Zhongxiang Pubic Health Bureau s. n. (HIB [0101695]). All photos by Cai-Fei Zhang, except J by Miao Liao, E by Bing Liu in Beijing and K by Qin-Wen Lin in Beijing.