Cytisus borysthenicus Gruner in Bull. Soc. Imp. Naturalistes Moscou 41(4): 446 (1869)

Sennikov, Alexander N. & Tikhomirov, Valery N., 2024, Atlas Florae Europaeae notes, 33. Taxonomic synopsis of East European species of the Cytisus ratisbonensis group (Fabaceae), PhytoKeys 238, pp. 157-197 : 157

3. Cytisus borysthenicus Gruner in Bull. Soc. Imp. Naturalistes Moscou 41(4): 446 (1869)

- Cytisus biflorus subsp. borysthenicus (Gruner) Pacz. in Trudy Bot. Sada Imp. Yur’evsk. Univ. 15(2-3): 95 (1914) - Chamaecytisus borysthenicus (Gruner) Klásk. in Preslia 30: 214 (1958) - Chamaecytisus biflorus subsp. borysthenicus (Gruner) Elenevsky & Radygina in Elenevsky et al., Rast. Saratov. Pravober.: 41 (2000).

Type.

Ukraine. Zaporozhie Region : "In demissis ad Borysthenem infra urbem Alexandrowsk [Zaporozhie]," [26.07].1865, L. Gruner (lectotype MW0475698, designated here). Fig. 4 .

Description.

Upright shrubs with erect stems up to 120(200) cm tall and long branches. Leaves with lanceolate leaflets, densely and evenly hairy above, with dense appressed hairs 0.1-0.2(0.3) mm long below, petioles densely covered with appressed hairs. Flowers strictly lateral, 1-4 in axils, on pedicels 2-5 mm long, yellow; calyx 10-12 mm long, with appressed hairs 0.4-0.6 mm long; standard suborbicular, hairy above.

Distribution.

Europe: Ukraine, Crimea ( Yena and Khlevnaya 2015a, 2015b; Fedoronchuk 2022), Russia (southern part: Kreczetowicz 1940; Borisova 1964). Asia: Russia (north-western Caucasus: Kreczetowicz 1940; Grossheim 1952; Ivanov 2019; south-western Siberia: Kreczetowicz 1940; Kurbatsky 1994), Kazakhstan (north-western part: Tulaganova 1981). New to Bashkiria, Bryansk and Kursk Regions of Russia. The presence in Belarus and European Kazakhstan is expected, but not confirmed.

Ecology.

Alluvial sands in larger river valleys, sandy steppes, open sands, sparse pine forests on sands, mostly along rivers.

Chromosome counts.

2n = 100 ( Semerenko 1984, as Chamaecytisus sp.); material collected from native populations in Ukraine; vouchers at KW.

Notes on nomenclature.

Leopold Gruner ( Lipschitz 1950; Leonov et al. 2014) explored the flora of steppic, sandy and calcareous areas near the confluence of the Konka River with the Dnepr River (now Zaporozhie Region, Ukraine).

Gruner (1869a, 1872) found Cytisus borysthenicus in a single place between the Konka River and Alexandrowsk Town (now Zaporozhie), rather frequent on small hills of partly open sands. While describing the new species, Gruner (1869a: 137) left it unnamed; in the second part of his synopsis ( Gruner 1869b: 446), he mentioned in a note under Cuscuta monogyna that the latter species was collected on Cytisus borysthenicus . Since both papers were part of the same work and it was the only species of Cytisus recognised in the territory, the name of that species has been commonly accepted as validly published with a cryptic reference to the description via the title of the work (Art. 38.12 and 38.14, see also Ex. 19 under Art. 38.11).

Gruner (1869a, 1869b) visited the locality of C. borysthenicus twice, on 20 June and 26 July 1865. He collected sterile twigs and only one flowering branch with three flowers during his first visit and observed abundant plants of Cuscuta monogyna on these shrubs during the second visit.

Herbarium collections of Leopold Gruner are known at LE and MW ( Lipschitz 1950). A minor part of his collections is placed at KW (formerly at CW: Leonov et al. (2014)). Some specimens are deposited at OXF ( Clokie 1964), acquired as part of the collections of William Wilson Saunders ( Druce 1897).

Kreczetowicz (1941) stated that the type of this species name is kept in Moscow, but it was not found anywhere including MW ( Gubanov 2002). Lipsky (1899) recorded 237 specimens collected by Gruner in Ukraine and accessioned to the collections of the Imperial Botanical Garden in Saint-Petersburg (now part of the Komarov Botanical Institute, LE). This figure is much smaller than the number of taxa recorded by Gruner in his work, meaning that his collection acquired by LE was highly incomplete. We were also not able to trace any specimen collected by Gruner and labelled as C. borysthenicus in any Herbarium.

As a matter of surprise, one specimen representing Gruner’s collection of Cuscuta monogyna , with Cytisus borysthenicus as a host plant, has recently resurfaced at MW. This specimen was clearly associated by Gruner with the protologue of C. borysthenicus and is, therefore, part of the original material of the latter name. Although the fragment of C. borysthenicus on this specimen is a sterile branch densely covered by a parasite, it is perfectly adequate to identify the species and may serve as lectotype.

The original description of C. borysthenicus is ambiguous. The ecology (sandy hills) and the hairy standard indicate this species as currently understood, whereas the obovate-lanceolate leaves, glabrous above, clearly refer to C. ruthenicus . This discrepancy was neglected by Paczoski (1914) and Kreczetowicz (1940), who resurrected the name C. borysthenicus and applied it to the psammophilous species with narrowly lanceolate leaves, hairy above. Cytisus borysthenicus , C. ruthenicus and their hybrid co-occur in the locus classicus of the first species ( Sennikov and Tikhomirov 2024a), and the original description of C. borysthenicus was apparently based on specimens of both species.

So far, the original material of C. borysthenicus , which is taxonomically referable to C. ruthenicus , has not been found. Gruner’s specimen of Cuscuta monogyna on Cytisus borysthenicus apparently belongs to the species as established by Paczoski (1914), Kreczetowicz (1940), Tzvelev (1987) etc. To fix this species name in its established interpretation, we designate the only available element of the original material as lectotype.

Notes on taxonomy and distribution.

This species is largely confined to the systems of southern East European rivers and was probably dispersed with sand deposits. Its distribution extends much further north-east and north-west than was indicated by Tzvelev (1987).

Figures

Figure 4. Lectotype of Cytisus borysthenicus Gruner.