Lectotypification of two names of Carex buekii hybrids (Cyperaceae) and notes on their morphology, ecology and distribution Author Wieclaw, Helena https://orcid.org/0000-0002-8165-6532 Institute of Marine and Environmental Sciences, University of Szczecin, Adama Mickiewicza 18, 70 - 383, Szczecin, Poland helena.wieclaw@usz.edu.pl Author Řepka, Radomir https://orcid.org/0000-0002-9993-0042 Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University, Zemedelska 3, CZ- 613 00 Brno, Czech Republic Author Koopman, Jacob https://orcid.org/0000-0002-8235-1108 ul. Kochanowskiego 27, 73 - 200 Choszczno, Poland text PhytoKeys 2023 2023-12-21 236 179 186 http://dx.doi.org/10.3897/phytokeys.236.113435 journal article http://dx.doi.org/10.3897/phytokeys.236.113435 1314-2003-236-179 AA73F6F1A34658A0A58EB81E9CEE79AC Carex x ligniciensis Figert, Allg. Bot. Z. Syst. 6: 38 (1900) [C. buekii x C. nigra]. Lectotype (designated here). Poland. Flora von Schlesien. Liegnitz: Parchwitz, auf einer Wiese an der Katzbach unter den Stammarten. 10/6/99. Leg. Figert (WRSL barcode WR GS 066846; isolectotype WRSL barcode WR GS 058738) (Fig. 1 ). Figure 1. The lectotype of Carex x ligniciensis Figert (WRSL barcode WR GS 066846). Photo: Herbarium, Museum of Natural History University of Wroclaw , Poland. Morphology. The hybrid is mostly intermediate between the parental species and characterised by the following traits: +/- tussocks 25-40 cm high, with numerous, shorter or longer creeping rhizomes; stems slender, with reddish brown to purple scale-like, non-reticulate basal sheaths, rough on the edges in the lower half; leaf blades 3-4 mm wide, with very long acuminate, bristle-like tip, very rough on the margin, dark green to grey-green; male spikes 1-2, oblong-cylindrical, glumes brown-black to black, obtuse, with a light central stripe, female spikes 3(-4), narrow, short cylindrical, proximate, lowermost slightly distant, lax at base, ca 4 cm long, pedunculate; female glumes ovate, shorter than utricles, dark brown; utricles empty, small, non-deciduous, green, without veins; lower bract shorter than inflorescence ( Grulich et al. 2023 ). Wallnoefer (2006) stated that this hybrid has amphistomatic leaves (stomata on both sides of the leaves). This trait makes this hybrid impossible to confuse with the other C. buekii hybrids, which have only stomata on the lower surface of the leaves (hypostomatic). The first of the parental species, C. buekii , is hypostomatic while in the second one, C. nigra , the stomata are found on the upper (adaxial) side of the leaves (epistomatic). Ecology. This hybrid was found in floodplains of large rivers where both parental species could meet. However, C. nigra avoids warm areas with the exception of isolated lowland fen sediments in previously flooded meadows, which corresponds to all known finds of this hybrid so far. Distribution. Carex x ligniciensis is relatively rare and has been found so far in Poland, the Czech Republic and Italy ( Koopman 2022 ). The specimens in BRNL, BRNM, CB, PR, and PRA were collected in the Czech Republic between 1921 and 1995, and they lack field verification. Therefore, we could consider it missing or even extinct at this locality. On the other hand, C. x ligniciensis is a very inconspicuous and apparently overlooked plant. In the Czech Republic, only one recent locality is known from the floodplain of the River Morava near the town of Kromeriz . As far as we know there are no recent findings of this hybrid in Poland, while its occurrence in Italy is at least questionable, as C. buekii is extremely rare in this country ( Koopman et al. 2018 ). The sterility of C. x ligniciensis limits it dispersal, however, the persisting of hybrid populations probably depends on vegetative reproduction, like with other sterile hybrids in Carex ( Pedersen et al. 2016 ). The spontaneous recurrence and survival of hybrids under natural conditions are a driving force of plant speciation (e.g. Mallet 2007 , Soltis 2013 ).