Carex × vratislaviensis Figert, Allg. Bot. Z. Syst.

Koopman, Jacob, Dajdok, Zygmunt, Więcław, Helena, Martinetto, Edoardo, Grulich, Vít, Řepka, Radomír & Jiménez-Mejías, Pedro, 2018, Global distribution of Carex buekii (Cyperaceae) reappraised, Phytotaxa 358 (2), pp. 139-161 : 148-150

Carex × vratislaviensis Figert, Allg. Bot. Z. Syst. 6: 39 (1900)

[ C. acuta × C. buekii ]

≡ C. buekii Wimmer var. melanostachya R. Uechtr., Jahresber. Schles. Ges. Vaterl. Cult. 43: 236 (1865 publ. 1866)

Although C. × vratislaviensis has been relatively widely reported, the studied material revealed that such statements derive from the apparent intermediate morphology of the basal sheaths. Carex buekii displays rigid scale-like, more or less elongated, entire basal sheaths, conspicuously dark reddish and reticulate-splitting. On the other hand, C. acuta rarely displays conspicuous basal sheaths, and when it does, they are shortly scale-like, brownish, never reticulate-splitting, papyraceous and deciduous (cf. Chater 1980; Egorova 1999; Jiménez-Mejías et al. 2014a). Besides, C. acuta tends to keep the remains of old leaves at the base of the flowering stems. However, these characters of the basal sheaths are highly dependent on soil conditions and season. Pure populations of C. buekii , observed in Piedmont ( Italy), can bear old leaf remains from the year before at the base of the flowering stems, superficially resembling C. acuta . We consider that the identification of the hybrid also has to rely on the intermediate character of the utricles: yellowish, swollen, covered by low papillae, and conspicuously nerved in C. acuta , while biconvex, from greenish-grey to tinged or dark brown, narrowly biconvex, with inconspicuous papillae, and faintly nerved or nerveless in C. buekii .

Uechtritz (1865) described C. buekii var. melanostachya , before any C. buekii hybrid was detected. Figert (1898) supposed this variety to be identical to C. acuta × C. buekii , which he named in 1900 as C. × vratislaviensis . Later, Kneucker (1911) put C. buekii var. melanostachya into synonymy of C. × vratislaviensis .

This hybrid is said to occur in Poland, Germany, Czech Republic, Slovakia, Austria, Hungary ( Soó 1973: 258), and Italy ( Koopman 2015). It is also mentioned from Switzerland ( Koopman 2011), but that must be considered at best doubtful, as the occurrence of C. buekii in this country seems to be very rare. Řepka (1985) mentioned this hybrid from two localities in the Czech Republic, N of Brno and one in N Moravia. In a second paper Řepka & Lustyk (1998) reported C. × vratislaviensis from another five sites in S Bohemia (Šumava Mts), in the vicinity of the villages of Pěkná and Želnava, in the River Vltava basin.After a thorough study of herbarium specimens of the entire section Phacocystis from the Czech Republic, a total of 287 localities for this hybrid were confirmed. This number also includes fully fertile plants originated by introgression of a parent species, most frequently C. acuta . This collection consists of approximately 35% intermediate types, 5–10% types closer to C. buekii and the remaining 55% is closer to C. acuta in morphological characters. All these specimens are, however, distinguished by the combination of the following characters: the spikes, especially the lower ones, are typical, having a width not exceeding 5 mm and their length-width ratio, thus being relatively long to long and thin, sometimes nodding and conspicuously pedunculate; quite often the lower part of the female spike is interrupted; the bract of the lowest spike has a variable length, resembling either C. buekii or C. acuta ; the utricles are smaller than in C. acuta ; the glumes dark, small, not markedly exceeding the length of the utricles. The leaf sheaths of C. × vratislaviensis vary with the gene flow of the parent species: from reddish-brown, robust, shiny, reticulate sheaths, to intermediate types that has smaller and slender sheaths than C. buekii , dark reddish brown, in spring with distinctive reticulate sheaths and in summer without. However, most of the material studied resembles C. acuta , with dark brown sheaths, the hybrid origin of these plants is shown primarily by the generative organs., It differs from the relatively similar C. randalpina by much narrower leaves, which never exceed the width of C. buekii , and which are mostly grey-green, and by the more graceful appearance of the inflorescences: the spikes are never as long and wide as those of C. randalpina .

A small proportion of the specimens were found to be sterile; most of the plants were fully fertile. The distribution of this hybrid in the Czech Republic is very interesting (Grulich & Řepka in prep.).Although most localities correspond with the distribution of C. buekii , i.e. C. × vratislaviensis grows on river banks and in floodplains, but particularly in the south of Bohemia and southwest Moravia, this hybrid expands further into the landscape, especially to places in lake basins, where it grows on banks of lakes and in adjacent marshes. These localities are mainly 8–10km (but up to 19km) from the river course. These plants are very probably introgressants of C. acuta , which behave in the wild as independent units thanks to their almost complete fertility. Their diaspores are transferred by waterfowl and, as with C. acuta , have a higher affinity to eutrophic marshes and the shores of reservoirs than C. buekii . Because C. acuta and C. buekii are closely related they have a tendancy to hybridise ( Fig. 1 ). Vollrath & Mergenthaler (1966) and Kiffe (2004) mentioned C. × vratislaviensis for Germany; the former recorded it from nineteen sites in the river valleys of Naab, Pfreimd and Schwarzach, all in Bavaria. In the several populations observed in Italy we have noticed a very broad variation, but we were not able to detect any evidence of the presence of C. × vratislaviensis . The occurrence of this hybrid in Italy is therefore at best doubtful.

Figures

FIGURE 1. Phylogenetic position of C. buekii Wimm. (red arrow) within the core clade of section Phacocystis, based on a ITS, ETS and matK phylogeny. Modified from Global Carex Group (2016).