A critical examination of specimens, with literature and a field survey have shown that Rubus pekinensis is conspecific with R. crataegifolius. Their morphological variations range can be defined as: leaves at the base may be ovate, suborbicular, narrowly ovate, entire, at the middle, ovate, narrowly ovate, oblong-lanceolate, palmately 3-lobed or 5-lobed and at the top, ovate, lanceolate, entire or 3-lobed; flowers solitary in the axillae or several flowers clustered at the terminal of branchlets or formed into short racemes. Therefore, we treat the former species as a synonym for the latter one.

Identity, new synonym, R. crataegifolius, Rosaceae, Rubus pekinensis

Rubus crataegifolius Bunge (1835: 98) was published, based on the collection from Pan-schan (Panshan), Hebei (now Tianjin), China A. Bunge s. n. (Syntypes LE [photo!], LE01015265, LE01015266, LE01015267, Fig. 1A–C). In the protologue, critical characteristics of the species were described as “Fruticosus erectus glabriusculus, ramis petiolis foliorum nervis pedicellisque aculeatis, foliis cordatis trifidis; lobis lateralibus acutis terminali acuminato acute inciso-dentatis, floribus axillaribus solitariis terminalibusque subracemosis; sepalis glabriusculis ovatis acuminatis erctis, petalis longe unguniculatis subspathulatis emarginatis, carpellis subexsuccis glabris”.

Figure 1. 

A–C syntypes of R. crataegifolius D syntype of R. ampelophyllus.

A. Gray (1858: 387) described a new species R. wrightii A. Gray on the basis of specimens collected from Hokkaido, Japan (Syntypes GH [photo!] GH00040766; K [photo!] K000737782, K000737783; NY [photo!] NY00391934; US [photo!] US00095501, Figs 2A–D, 3A). H. Léveillé and Vaniot (1905: 62) described R. ouensanensis H. Lév. & Vaniot in Bull. Soc. Agric. Sarthe, based on the collection from Ouen san, Corea U. J. Faurie 83 (Holotype E [photo!] E00010580; Isotypes A [photo!] A00040688 (Image of E00010580); G [photo!] G00437174; P [photo!] P00755199, P00755200, Figs 3B–D, 4A, B). H. Léveillé (1908: 279) described R. ampelophyllus H. Lév. in Repert. Spec. Nov. Regni Veg., based on the collection from Quelpaert, Corea U. J. Faurie 302 (Syntype BM [photo!] BM000622269, Fig. 1D). These three species were treated as synonyms of R. crataegifolius by Lu (1985: 117) and Lu & Boufford (2003: 236) in Flora of China.

Figure 2. 

A–D syntypes of R. wrightii.

Figure 3. 

A syntype of R. wrightii B holotype of R. ouensanensis C, D isotypes of R. ouensanensis.

Figure 4. 

A, B isotypes of R. ouensanensis C, D syntypes of R. itoensis.

H. Léveillé and Vaniot (1905: 62) published a new species R. itoensis H. Lév. & Vaniot, based on the specimens collected from Takeo, Kiushu, Japan U. J. Faurie 5365 (Syntypes BM [photo!] BM000622252; E [photo!] E00010657, Fig. 4C, D). According to its protologue, this species was described as similar to R. grossularia H.Lév. & Vaniot and R. incisus Thunb., but it differed by having peduncles, with large and numerous flowers. However, it was treated as a synonym of R. crataegifolius in Flora of Japan (Naruhashi 2001).

Focke (1917: 104) described a new species R. pekinensis Focke on the basis of the collection of O. Warburg 6549 from Miaofangshan (Miaofengshan), Beijing, China (Holotype B [photo!] B101154579, Fig. 5A). According to the holotype, features of the specimen can be described as “shrubs with slightly curved prickles; leaves simple, 3-lobed or undivided, margin irregularly incised-serrate; stipules linear, adnate; several flowers cluster in axillae”. In the protologue, the characters of this species can be defined as: “Praesto est ramus exsiccatus unicus florens non incolumis speciem vero memorabilem indicans. Ramus foliorum marginibus a petiolis decurrentibus subangulatus, cum petiolis glabriusculus et aculeis lanceolatis vel falcatis sparsis armatus. Folia longe petiolata, majuscula, circ. 16 cm. longa, 18 cm. inter angulorum lateralium apices lata, inaequaliter sat grosse serrata, utrinque parce pilosa; folia inferiora subquinqueloba, intermedia e fundo cordato-emarginata triloba, inaequalia, lobis oblongo-lanceolatis; suprema integra, lanceolata. Stipulae petiolorum basi insertae, lineares. – Flores in ramulis axillaribus complures, longe pedunculati, alii superiores terminales fasciculati; pedunculi 3–6 cm. longi, laxe pilosi, interdum aculeolo instructi; calyces parce pilosi, sepalis saepe mucronatis vel appendice subulata terminatis; petala, ut videtur, sepala vix superantia.”. However, the name R. pekinensis has never been used, except in its original publication, from the date of its publication. Thus, it is necessary to identify the species.

Figure 5. 

A holotype of R. pekinensis B–D specimens of R. pekinensis collected from Miaofengshan.

Herbarium specimens, including all kinds of type specimens deposited in A, B, BM, E, G, GH, K, LE, NY, P and US were critically examined and a field survey in the type localities was conducted. Six populations from Miaofangshan and Pan-schan were surveyed and collected in 2021. High resolution pictures of leaves and fruits were taken by a SONY α 7II.

Firstly, the examination of herbarium specimens, identified as R. ampelophyllus, R. crataegifolius, R. itoensis, R. ouensanensis and R. wrightii, indicated that they represented the same species. According to Art. 11.4 of the “International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code)” (Turland et al. 2018), R. crataegifolius is the correct name of this species. A comparison of type materials of R. crataegifolius and R. pekinensis showed that there are only a few differences in leaf morphology and inflorescence. So they also probably represented the same species.

Secondly, during the field survey to the type localities, three populations of the species R. pekinensis and R. crataegifolius were found from each location. All of the populations were at the fruiting stage and several observations regarding species identity were carried out in this Rubus group. The results can be described as: a) the morphological diversity of leaves is rich in different populations (Figs 1–6), even on the same plant (Fig. 8A–E). As Fig. 7 shows, leaves at the base may be ovate, suborbicular, narrowly ovate, entire, at the middle, ovate, narrowly ovate, oblong-lanceolate, palmately 3-lobed or 5-lobed and at the top, ovate, lanceolate, entire or 3-lobed. b) the diversity of inflorescence can be seen in R. crataegifolius and its synonyms, including R. pekinensis, such as the axillary flowers, solitary or several flowers clustered at the terminal of branchlets or formed into short racemes (Figs 1–6). c) the field survey in type localities of R. pekinensis and R. crataegifolius shows that they share characters of “branchlets angular, thinly pubescent when young, gradually glabrescent, with lanceolate or falciform prickles; leaves simple, middle-lower palmately 3–5-lobed, oblong-lanceolate, top entire lanceolate; stipules adnate to base of petiole, linear; flowers in branchlets axillary, others, terminal, short racemes or flowers several in a cluster; pedicel pubescent, sometimes equipped with aculeolus; calyx abaxially thinly pubescent, sepals narrowly ovate to ovate-oblong, apex acute to shortly acuminate, aggregate fruit red, glabrous” (Figs 5B–D, 6A–D, 7A–D). This is consistent with the protologue of Focke (1917: 104) and Bunge (1835: 98).

Figure 6. 

Specimens of R. pekinensis collected from Miaofengshan.

Figure 7. 

Specimens of R. crataegifolius collected from Panshan.

Figure 8. 

Morphological diversity of leaves A, B leaves of R. crataegifolius, collected from Panshan C–E leaves of R. pekinensis, collected from Miaofengshan.

Based on the analysis above and the characters defined from the type specimen, we can confirm that R. pekinensis, together with R. ampelophyllus, R. itoensis, R. ouensanensis and R. wrightii, are conspecific with R. crataegifolius. As R. pekinensis was published later than R. crataegifolius, R. pekinensis should be a synonym of R. crataegifolius, according to nomenclatural priority.

In the Flora of China, Lu and Boufford (2003: 284) indicated that R. pekinensis had been described from Peking (Beijing), China, but they have seen no specimens, and are therefore unable to treat it. Meanwhile, they stated that further revision of this species is necessary. In this paper, we carried out a field survey in the type locality from where morphological variations of R. pekinensis and R. crataegifolius in different populations were studied. There are many variations in the shapes of leaves both in R. pekinensis and R. crataegifolius, even in the same plant, where leaves simple, ovate, narrowly ovate, lanceolate or oblong-lanceolate, entire or palmately 3-lobed or 5-lobed, can be seen. Flowers solitary, clustered and short racemes sometimes co-existed in the same plant. This is consistent with the description of R. crataegifolius (Focke 1910, 1911, 1914). In further studies of Rubus, understanding the diversity of the species between different populations needs critical examination of specimens and field surveys, especially when a new species is being published.

We would like to express gratitude to Robert Vogt, curator of the Berlin herbarium (B), for providing Focke’s type material of R. pekinensis, and other curators of the herbaria: A, BM, E, G, GH, K, LE, NY, P and US. We are grateful to an anonymous reviewer for valuable comments and to postgraduate Sun Mengtao and Zhang Junxin’s help for specimen collection. This research was financed by the Beijing Municipal Education Commission under Grant KM201910020016.