The genus Rhaponticum in East Asia

The genus Rhaponticum in East Asia has always been a taxon for discussion. Rhaponticum carthamoides from East Siberia comprises three subspecies: carthamoides, chamarensis and orientale. Even though they differ in morphology, they do not have isolated areas. Rhaponticum satzyperovii was recently described and its author pointed out its affinity with Rh. uniflorum. Plant height, stem indumentum, and radical and stem leaf dissection were signaled as the diagnostic characters. Our present study on living and herbarium specimens of Rh. satzyperovii shows that the diagnostic characters are not consistent. The species area was also claimed to be an argument for considering Rh. satzyperovii a distinct species. This area covers the south of the Primorye Province in the Far East of Russia with some locations in the adjacent Jewish Autonomous Region and in China. In our study, the area of Rh. satzyperovii is found to be within the area of Rh. uniflorum and thereafter they turned out to have no disjunction. In East Asia, Rh. uniflorum is characterized by a wide range of morphological variability. We suggest that Rh. satzyperovii should be included within Rh. uniflorum without any taxonomic rank.


INTRODUCTION
Up to the present, the names Rhaponticum Vaill., Stemmacantha Cass.and Leuzea DC. have been used in floristic reports and in literature covering the studies on chemical composition of the plant species of Rhaponticum.The authorship of the name Rhaponticum was usually ascribed to Adanson (1763) and more recently to Vaillant (1718) according to Susanna and Garcia-Jacas (2007).However, this name was used as early as Bock, Prosperus, Bauhin and other authors (Dittrich, 1973;Holub, 1973Holub, , 1974)).
Many taxonomists developed the system of the genus Rhaponticum.In 1718 Vaillant used this name for a group of plants including species of the genera Leuzea and Acroptilon Cass., according to the contemporary conceptions.In 1742, Haller used the name Rhaponticum (Holub, 1973) for the association of four species of the Asteraceae.Ludwig (1747) published the genus name Rhaponticum and included 9 species into the genus.Linnaeus (1753) developed the classification of Rhaponticum, but he placed many species of Centaurea L. into this genus.Lamarck (1779) excluded C. rhapontica L. from Centaurea and transferred to the genus Rhaponticum as Rh.scariosum Lam.Later on, a number of authors clarified and changed the boundaries of the genus Rhaponticum (Jussieu, 1789;De Candolle, 1838;Ledebour, 1845;Bentham, 1876;Hoffmann, 1890).They even placed species of the genera Cnicus L., Serratula L., Cirsium Mill.and Centaurea into this genus.The genus name Rhapontica was suggested by Hill (1762) and the IAPT (International Association of Plant Taxonomy) resolved to consider this name to be homonym of Rhaponticum (Dittrich, 1984), which led to the generalized use of the genus name Stemmacantha Cass., described by Cassini (1818) with Serratula cynaroides DC. as the type species.Cassini (1818) considered the special structure of calyx bracts to be the distinguishing character of the genus.The classification of Stemmacantha proposed by Dittrich (1984) was adopted by Czerepanov (1995) and it included 20 species, 10 subspecies and 2 varieties.Finally, Greuter (2003) recovered Vaillant's names and assigned, hopefully this time definitely, the name Rhaponticum to the genus. 1n the literature on flora of Siberia, the Russian Far East (RFE), Mongolia, Korea and China and in publications on taxonomy of the Asteraceae, there is no agreement regarding the species composition of the genus Rhaponticum.In the check-list of Czerepanov (1995) there are three species of Rhaponticum (as Stemmacantha), namely St. carthamoides (Willd.)Dittrich, St. uniflora (L.) Dittrich and St. satzyperovii (Sosk.)Czer.reported for East Asia.
Rhaponticum carthamoides (Willd.)Iljin is distributed on subalpine meadows of Central and East Siberia, and outside Russia it grows only in two locations in the Mongolian Altai (Grubov, 1982;Zhirova, 1997;Doronkin, 2003) and is represented by three subspecies: Rhaponticum carthamoides subsp.carthamoides, Rh. carthamoides subsp.orientale (Serg.)Doronkin, and Rh.carthamoides subsp.chamarensis (Peschkova) Doronkin, that differ in morphological characters (shape of appendages of outer involucral leaflets), but do not have isolated areas.There are no other species related to Rh. carthamoides described from Siberia.In the south-eastern part of Siberia the area of Rh. carthamoides reaches the area of the southern lakeside of Baikal (Zhirova, 1997).
Rhaponticum carthamoides is used in Russia as a medicinal plant and as a source for ecdysteroid production.Mass harvesting of these species today accounts for working out measures on its conservation.The cited literature and synonyms are provided below.
Rhaponticum uniflorum (L.) DC. was reported in «Key-book of plants of Primorye and Primurye» by Vorobyev et al. (1966), who listed Rh.satzyperovii as a synonym.To the contrary, Voroschilov (1966) reported two species of Rhaponticum for the RFE, Rh. uniflorum and Rh.satzyperovii, and noted that in the territory of Primorye Province there are plants both similar to typical Rh. uniflorum and others with characters transitional between Rh. satzyperovii and Rh.uniflorum.Later on, Voroschilov (1982Voroschilov ( , 1985) ) combined Rh. satzyperovii as Rh.uniflorum subsp.satzyperovii (Soskov) Vorosch.
In the survey «Vascular plants of the Soviet Far East», Barkalov (1992) recognized two independent species: Rh. uniflorum and Rh.satzyperovii.
We carried out a study in order to ascertain whether Rh. satzyperovii is a different species from Rh. uniflorum.

MATERIALS AND METHODS
The paper is based on the study of living plants of Rh. uniflorum and Rh.satzyperovii collected during expeditions to nature populations in the Irkutskaya, Chitinskaya, Amurskaya and Jewish Autonomous Regions, Khabarovsky and Primorsky Provinces, and the study herbarium material in LE, MHA, MW, VLA, the Pacific Institute of Bioorganic Chemistry (Vladivostok), the Far-Eastern Branch of the Russian Academy of Sciences (FEB RAS), the Botanic Garden-Institute FEB RAS (Vladivostok), the Institute of aquatic and ecological problems FEB RAS (Khabarovsk), the Institute of Complex Analysis of Regional Problems FEB RAS (Birobidzhan), the Zabaikalsky State Pedagogical University of N.G.Chernyshevsky (Chita), the Blagoveschensk State Pedagogical University of M. I. Kalinin (Blagoveschensk), and literature data.

RESULTS AND DISCUSSION
Our study of living plants of Rh. satzyperovii, as well as observation of herbarium materials, has shown that the diagnostic characters indicated by Soskov (1959Soskov ( , 1963) ) are not consistent.The species description (Soskov, 1959(Soskov, , 1963) details that Rh. satzyperovii is close to Rh. uniflorum, but «… it has isolated area and is well distinguished by its robust stem up to 1 m high, lyrate radical leaves and large superficially partite, often pinnatilobate, stem leaves and a number of other characters…».Having observed more than 300 plants of Rh. satzyperovii in "locus classicus" we were able to collect some specimens that corresponded to Rh. uniflorum in their morphological characters.
We registered high variability in plants of both species.The most variable are the shape and dissection of radical and lower stem leaves, i.e. the characters that were considered to be distinguishing in the description of Rh. satzyperovii.Within a single population of Rh. satzyperovii there are plants with lyrate radical leaves with a large terminal lobe and slightly partite lobed stem leaves, as well as individuals with pinnatipartite or pinnatifid leaf blades without a large terminal lobe.Often in the same leaf rosette there are leaves of two forms with all transitions between them.Such pattern is typical to both Rh.satzyperovii from "locus classicus" and the plants in the northernmost location of the area (by Soskov YU.D.) of Rh. satzyperovii in the Jewish Autonomous Region in the vicinities of Bidzhan Settlement.Such pattern in leaf variability is observed in plants of Rh. uniflorum.The species characters that describe Rh. satzyperovii easily fit into character variability of Rh. uniflorum.We have not found any differences between Rh. uniflorum and Rh.satzyperovii in morphological characters.
Within the species one can find plants with xeromorphic pattern: dwarfish, with small dissected (often as deep as to the central costa) leaf blades with up to 12 pairs of narrow-lanceolate lobes.Usually those are plants which grow in open southern steppe or stony hill slopes.Xeromesophytic plants are tall (up to 1 m high), with large, pinnatilobate or slightly partite into 3-8 pairs of wide ovate-oblong lobes, lyrate leaves -they often occur on elevated sites river valleys, sea shores, sometimes under forest canopy.Plants with xeromorphous pattern grow in the north-western part of the area in the regions with continental, arid climate (the Tuva and Buryatiya Republics, the Irkutskaya, Chitinskaya and the north of Amurskaya Regions, Mongolia, North and Central China).Plants with xeromesophytic pattern are restricted to the regions with humid, warm, monsoon climate (the southern areas of the Amurskaya Region, the Jewish Autonomous Region, Primorsky Province, North-East China and Korea Peninsula).
The area of Rh. satzyperovii (Soskov, 1959) covers the territory of south Primorsky Province of the RFE, the Jewish Autonomous Region (Stolbovoye Village and Bidzhan Settlement) and North-East China (near Sochintsy, Matsyaokhe Station).In the area of Rh. uniflorum, Soskov (1963) reports a significant disjunction from the northern part of Zeya-Bureya floristic region (in the Amurskaya Reion) and «…as a carried plant on the Muraviov-Amursky Peninsula, Putyatin Island and in the vicinities of Ussuriysk city …».
While specifying the growth locations of Rh. uniflorum in Russia, Mongolia, China and Korea we ascertained that this plant does not occur in the Russian Far East and Siberia as a carried plant and the area of the species turned out to be continuous (with no disjunction).The area continuity of Rh. uniflorum is provided by this species growing in North-Eastern China (Manchuria).Rh. uniflorum, which is characterized by a wide range of morphological variability, grows in East Siberia, Mongolia, Central, North and North-East China, Primorsky and south Amursky Provinces, and the Korean Peninsula.The area of Rh. satzyperovii is then within the area of Rh. uniflorum.