Taraxacum erythrospermum Andrz.

Dudáš, Matej, Kolarčik, Vladislav, Šuvada, Róbert & Vašut, Radim J., 2024, Taraxacum sect. Erythrosperma (Asteraceae, Cichorioideae) in Slovakia IV. Distribution of T. erythrospermum and synonymisation of T. slovacum, Phytotaxa 646 (3), pp. 265-281 : 267-273

Taraxacum erythrospermum Andrz. in Besser (1822: 75).

Type:— UKRAINE. “In Volhynia et Podolia frequens” (lectotype LE, designated by Shiyan et al. (2012)) .

= Taraxacum corniculatum f. pusillum Dvořák (1928: 27) .

Type:—Not designated.

= Taraxacum slovacum Klášterský (1938: 8) , syn. nov.

Type:— SLOVAKIA. “ Slovenia austro-orientalis, Slovenský Kras, silvis apertis Zadielský Kámen dictis in declivibus meridionalibus supra cotam 271 prope Zádiel”, 06.1933, I. Klášterský & M. Deyl (lectotype PRC! #487724, left plant in the middle of the specimen, designated here) ( Fig. 1 ).

= Taraxacum austriacum Soest (1966: 434) .

Type :— AUSTRIA. „Nieder-Oesterreich:Wegraine südlich Petronell“, 11.05.1944, K. H. Rechinger (lectotype W #1998-01081, designated by Kirschner & Štěpánek (2014); isolectotype W #1998-01080) .

= Taraxacum austriacum f. achyrocarpum Soest (1966: 436) .

Type:— AUSTRIA. „Wienerwald, Bierhauselberg bei Rodaun“, 12.05.1911, Korb (holotype W).

= Taraxacum punctatum Richards (1970: 111) ≡ Taraxacum austriacum var. punctatum (A.J.Richards) Doll (1973: 22) .

Type:— SLOVAKIA. Kováčovské kopce, 05.1965, D. M. Valentine (holotype OXF #54689).

Taraxacum erythrospermum is a small plant usually only up to 10 cm tall, with a tunic of withered leaves at the base of a rich leaf rosette, mostly with deeply dissected and laciniate leaves. Leaves are greenish or greyish-green, glabrous, 3–10 (–15) cm long and (0.5–)0.7–1.5(–2.0) cm wide with 3–5 very variable lateral lobes, usually narrow, often linear, obtuse at the apex and denticulate; the terminal lobe is regular and triangular (outer leaves) to trilobate and linear (inner leaves). Petiole narrow, greenish to violet, sometimes lanate at the base. Scapes many (up to 30), usually equalling leaves, base gradually narrowed (V-like shaped); outer bracts tightly to not tightly adpressed, rarely suberect, usually (7–) 9–11, narrowly lanceolate to ovate, greyish-green, occasionally reddish, with a hyaline margin, up to 0.5 mm wide, corniculate at the apex; capitulum concave (styles exserted), pale yellow, small, 10–15 mm in diameter; outer ligules striped pale greyish-yellow to reddish brown; styles usually yellow or greenish-yellow; pollen present, pollen grains ca 27 μm in diameter, not varying in size (but sporadically of different size). Achenes are usually red, rarely greyish ( Fig. 3 ), small, 1.8–4.3 mm long, achene body densely spinulose above, cone 0.2–1.5 mm long.

As T. erythrospermum is a sexually reproducing species, it has a large morphological variation, unlike in apomictic microspecies ( Vašut 2003, Šuvada et al. 2010, Majeský et al. 2015). Some distinct morphologic variants were described as forms, such as the form with greyish achenes ( Soest 1966; Fig. 3 ), or dwarf forms collected on the serpentinites ( Dvořák 1928). Although they might appear distinct, they do not represent taxonomically important variants. The morphotype with grey-coloured achenes—known as f. achyrocarpum Soest (1966: 436 ; e.g. adopted by Vašut 2003; Mártonfiová et al. 2010; Dudáš et al. 2013)—is scattered throughout the distribution area of the species ( Figs. 4 and 5 ). The growth-size of plants strongly depends on the environmental condition and vary considerably, therefore describing tiny plants as a distinct form does not make any taxonomic importance. An image of the plant described by R. Dvořák as T. corniculatum f. pusillum looks like typical T. erythrospermum ( Dvořák 1928, pl. I, fig. 4).

Notes on Taraxacum slovacum

The holotype specimen ( Fig. 1 ) represents a young plant lacking well-developed inner leaves, and it was therefore difficult to interpret the taxon. The plant on the holotype specimen has clearly compressed outer bracts (phyllaries), which are narrow and tiny, a thin stem below the capitulum, and apparent remnants of dried leaves at the base of the leaf rosette—these are unambiguous characters of the diploid species T. erythrospermum . Unfortunately, there was no flowering with pollen, which would have confirmed either sexual or apomictic reproduction.

There were doubts about the leaf shape, and the apomictic species T. pudicum Vašut & Majeský (2015: 244) superficially resembled the leaves of the left plant on the holotype specimen. Intensive field surveys confirmed the frequent occurrence of diploid T. erythrospermum at the locus classicus, often with the (unusual) triangular terminal lobe, as is the feature of the plant on the type specimen. The only apomictic species at the putative classical locality was T. prunicolor Schmid et al. (2004: 221) . However, combining the facts that the plant on the holotype falls within the morphological variation of T. erythrospermum , and that only diploids are the common taxon at the classical site, we consider T. slovacum a synonym of T. erythrospermum .

Distribution in Slovakia

Our results show that T. erythrospermum is the most frequent species of T. sect. Erythrosperma in Slovakia. In total, we recorded the species presence in 24 phytogeographical regions and sub-regions (out of 31). In the area of the Carpathian flora (Carpaticum) it occurs in 16 phytogeographical districts and subdistricts, while in the area of the Pannonian flora (Pannonicum) it occurs in all 8 districts, as shown on the distribution map ( Fig. 4 ). The northern limit of its occurrence is delimited by the line between cities of Ilava – Banská Bystrica – Revúca – Rožňava – Gelnica – Trebišov – Kráľovský Chlmec. Isolated but frequent occurrences are known on xerothermic travertine hills around the town of Spišské Podhradie. The morphotype with grey-coloured achenes was found in the Slovenský kras and the Východoslovenská nížina lowlands in the Pannonian region and in the Tribeč Mountains and the Stredné Pohornádie valley in the Carpathian region ( Fig. 5 ).

Ecology and cenology

Based on the classification of our own phytocenological records with the confirmed occurrence of T. erythrospermum ( Fig. 6 ), we can conclude that this species mostly prefers dry, perennial rocky grasslands on carbonate substrates, which we classify according to the Catalog of Habitats of Slovakia in category TRB08, and it includes communities of the alliance Bromo pannonici-Festucion pallentis.

The species is also often found in dealpine calciphile pale fescue grasslands, which are represented by the alliance Diantho lumnitzeri-Seslerion (habitat TRB09) and which are often situated in a mosaic with pioneer vegetation of the alliance Alysso alyssoidis-Sedion albi (PIP05). In dry steppe grasslands, it also finds suitable stands in the vegetation of the alliance Festucion valesiacae (TRB03) and in the more nutrient-rich thermophilic meadows of the alliances Cirsio-Brachypodion pinnati and Bromion erecti (TRB01). In more mesophilic habitats, the species grows less often in the hay meadows of the alliance Arrhenatherion elatioris (LKP01) and in the mesic permanent pastures of the alliance Cynosurion cristati (LKP03).

It is quite interesting that the species also rarely occurs in lowland to montane, dry to mesic mat-grass swards with a vegetation of the alliance Violion caninae (LKP10a). Especially in the Slovenský kras, this is the vegetation that occurs in areas that were intensively grazed in the past, which is located in a complex with the thermophilic vegetation mentioned above.

The species can also be found along tourist paths, on hills with roadside crosses, on castle hills, in stone-pits and on hilltops around transmitters, rarely on the edges of light oak and white agate forests. Its altitudinal range extends from 120 to 650 m above sea level, rarely at altitudes from 700 to 900 m; the maximum altitude was recorded in the top parts of the Mt. Ohnište (ca 1500 m) in the Nízke Tatry Mts (without an exact number and exact location).

Genome size

The genome size (2C value) measured per individual T. erythrospermum plant ranged from 1.529 pg (Spišský hrad population) to 1.604 pg (Zádielské Dvorníky), with a mean value of 1.554 pg (± 0.024 SD). This variation represents a 4.93% difference in genome size. Low between day variation allows to test for interindividual genome size variation, which was found statistically significant (ANOVA, genomes size ~ individual plant, F 8,26 = 23.72, p <0.001). Further based on Tukey`s post hoc test, we have revealed three statistically homogeneous groups, i) a group with mean genome size of 2C = 1.54 pg (± 0.007 SD, six individuals in range of 1.529 –1.548 pg), ii) a group of two samples (from different localities) with identical genome size of 2C = 1.573 pg, and iii) single sample with 2C = 1.604 pg.

Discussion

Taraxacum erythrospermum is very variable species in many morphological characters in leaves and flower parts. Two distinct morphotypes described as forms from Central Europe ( T. austriacum f. achyrocarpum Soest and T. corniculatum f. pusillum R. Dvořák ) are considered synonymous with the species, as they never occur alone, but only rarely add to the morphological variation of the whole population. Another species, T. punctatum , was described before T. erythrospermum was accepted as a sexually reproducing species with a wide morphological variation. Its holotype specimen collected by D. M. Valentine in 1965 in the Kováčovské kopce Mts. was marked with a diploid number of chromosomes by the author himself. In the description of the taxon, Richards (1970) gave two ploidy levels, which cannot be accepted with respect to the present taxonomic concept of the section. The name T. punctatum is, in accordance with the diploid chromosome number of the holotype, and having pollen grains of regular size, included among the synonyms of T. erythrospermum .

Den Nijs et al. (1990) mentioned the distribution of diploid Taraxacum species with its centre in southern Slovakia. Branches of the diploid area follow the river valleys (e.g. Váh, Nitra, Hron) and reach some of the intra-Carpathian valleys (e.g. Hornádska kotlina basin). Within this area, diploids are found in a variety of habitats, from dry to mesophilous. Outside this region, a rapid decline of diploids can be observed, and diploid plants are restricted to dry, sunny, often stressed habitats along roads and in villages and towns.

The first distribution map of T. erythrospermum in Slovakia was published by Šuvada (2008: 26, map 5.1), but this map was based on the author’s own recent distribution data, mainly from the Slovenský kras Mts., without using voucher specimens in public herbaria. Later, Šuvada (2010: 53, Fig. 1 ) published a distribution map of T. erythrospermum in the Pannonian Plain using recent distribution data and data from several public herbaria. The distribution map of neighbouring Moravia (in Czechia) was published by Vašut (2003: 317, fig. 3), while the distribution of this species in Hungary is still unknown.

The genome size estimate differs from the values recorded in the Czech Republic, with records ranging from 1.41 pg ( Šmarda et al. 2019) to 1.75 pg (Macháčková et al. 2019). These differences are due to different standardisation of the measurements and because of a bias due to different internal standards (and thus recalculation).

Figures

FIGURE 1. Holotype specimen of Taraxacum slovacum (PRC! #487724).

FIGURE 3. Variation of the achene colour of Taraxacum erythrospermum. Left: typical form; right: greyish form. Bar scale = 1 mm.

FIGURE 4. Distribution of Taraxacum erythrospermum in Slovakia (full dots); empty circles: T. cf. erythrospermum.

FIGURE 5. Distribution of Taraxacum erythrospermum with grey-coloured achenes in Slovakia.

FIGURE 6. Detrended correspondence analysis of 105 phytosociological relevés with confirmed occurrence of the diploid species Taraxacum erythrospermum classified to habitat type with the Ellenberg-type indicator values displayed as a passive vectors. Blue square—TRB01 (Cirsio-Brachypodion pinnati and Bromion erecti), blue circle—TRB03 (Festucion valesiacae), blue diamond—TRB08 (Bromo pannonici-Festucion pallentis), blue star—TRB09 (Diantho lumnitzeri-Seslerion), green square—PIP05 (Alysso alyssoidis- Sedion albi), red square—LKP01 (Arrhenatherion elatioris), red circle—LKP03 (Cynosurion cristati), red diamond—LKP10a (Violion caninae). Ordination scores of the displayed species (species weight range) are more than 0.35, Taraery—Taraxacum erythrospermum, Carehum—Carex humilis, Festval—Festuca valesiaca, Koelmac—Koeleria macrantha, Poteare—Potentilla arenaria, Teuccha—Teucrium chamaedrys, Tithcyp—Tithymalus cyparissias. Axis eigenvalues: 0.529 and 0.239; DCA1 (abscissa) axis length: 4.034; DCA2 (ordinate) axis length: 2.390.