Carex flava agg. (section Ceratocystis, Cyperaceae) in Poland: taxonomy, morphological variation, and soil conditions

Abstract

Sedges of Carex flava agg., typical of moist or wet habitats, are difficult to classify because of a lack of clear-cut morphological differences between them and the existence of numerous hybrids. This monograph presents results of research conducted in 2007-2012 in various parts of Poland. The plant material consisted of 1852 living specimens of Carex flava agg., collected from 80 localities, and dried specimens from 26 herbaria and from 7 private collections. The analysis involved 45 morphological characters (34 quantitative and 11 qualitative) and 9 soil parameters. Univariate, bivariate, and multivariate statistical methods were used to process the data. The results confirm the taxonomic classification dividing the C. flava group into 4 species: C. flava s.s., C. lepidocarpa, C. demissa, and C. viridula. This classification is based on (i) a high observed level of morphological separation of these taxa, resulting mostly from differences in generative characters, i.e. length of the utricle and its beak, and percentage ratio of beak length to total utricle length; (ii) integrity of the taxa at the sites where they coexist, although some intermediate forms resulting from hybridization are also present; (iii) habitat preferences of the taxa, especially the preference of C. lepidocarpa for calcareous sites and of C. demissa for slightly acidic soils. Thus in Poland the analysed taxa are morphologically well-defined and show clear ecological preferences. Continuous variation of morphological characters was observed among specimens of C. viridula, so it is not justifiable to distinguish its subspecies (sometimes classified even as separate species), described previously in literature. Consequently, the 2 subgroups of C. viridula were treated as local variants (i.e. varieties: var. viridula and var. pulchella), considering their different habitat requirements. Additionally, 5 hybrids were distinguished within C. flava agg.: C. ×alsatica [= C. demissa × C. flava], C. ×ruedtii [= C. flava × C. lepidocarpa], C. ×schatzii [= C. lepidocarpa × C. viridula], C. ×subviridula [= C. flava × C. viridula], and C. demissa × C. viridula; as well as 2 hybrids with C. hostiana as one of the parents: C. ×fulva [= C. demissa × C. hostiana] and C. ×leutzii [= C. hostiana × C. lepidocarpa].

Genetic differentiation, phenotypic plasticity and adaptation in a hybridizing pair of a more common and a less common Carex species

“…The taxa belong to the C. flava L. species group (Cyperaceae). So far, most studies of the C. flava group were taxonomically motivated and based on field-collected fresh or herbarium material (Stoeva and Stepankova, 1990;Hedrén, 2002;Blackstock and Ashton, 2010;Więcław, 2014), while studies of species relationships and their responses in common gardens are very scarce and included material only from small regions (Davies, 1953a;Schmid, 1984aSchmid, , 1986. Therefore, we did a large 3-year transplant experiment across three regions: Estonia and Lowland and Highland Switzerland (Fig.…”

Despite admixing two closely related Carex species differ in their regional morphological differentiation

“…The morphology of the C. flava group species has therefore been addressed, e.g. in the British Isles (Davies 1953b;Blackstock and Ashton 2010), in Bulgaria and former Czechoslovakia (Stoeva and Stepankova 1990), in Finland (Pykälä and Toivonen 1994), in Fennoscandia (Hedrén 2002), in Spain (Jiménez-Mejías et al 2012, 2014, in Poland (Więcław 2014), in Switzerland (Schmid 1980(Schmid , 1983 and in North America Ball 1989b, 1989a). However, the amount of regional morphological variation between climatically different geographic regions, and whether it differs between taxa, is not clear.…”

“…Hybridization in sedges may have recently increased quite dramatically as a consequence of anthropogenic habitat disturbance (Cayouette and Catling 1992). Hybridization between members of the C. flava complex was reported across their distribution ranges (Schmid 1982(Schmid , 1983Crins and Ball 1989b;Hedrén 1990;Egorova 1999) and was demonstrated to result in morphologically intermediate individuals (Stoeva and Stepankova 1990;Blackstock and Ashton 2010;Więcław 2014). Studying the differentiation between hybrids from different regions would show whether the hybrids evolve differently in different regions and thus add to local biodiversity.…”

Carex flava agg. (section Ceratocystis, Cyperaceae) in Poland: distribution maps and locality lists

“…pulchella (Lönnroth) B. Schmid, and the following 7 hybrids: C. ×alsatica Zahn, C. ×ruedtii Kneuck., C. ×schatzii Kneuck., C. ×subviridula Fernald, C. demissa × C. viridula, C. ×fulva Gooden., and C. ×leutzii Kneuck. (Więcław 2014). Among them, C. hostiana and C. flava are morphologically best defined, usually easily identifiable.…”

“…Among them, C. hostiana and C. flava are morphologically best defined, usually easily identifiable. Delimitation of other taxa of the section Ceratocystis is difficult because of their variable morphology, overlap of ranges of many characters, and appearance of hybrids whose characters are intermediate between those of parental species (Więcław 2014).…”