Achillea asplenifolia Vent. is one of three central European diploid species (together with A. setacea Waldst. et Kit. and A. roseoalba Ehrend.) of the A. millefolium group. Its taxonomic and phytogeographic account from the central European perspective is given mainly on the basis of herbarium and field studies. The synonymy of A. asplenifolia includes A. millefolium var. crustata Rochel and A. scabra Host; both names are typified here. No variation deserving taxonomic recognition was observed. From the taxonomic point of view, A. asplenifolia is a clearly delimited species. It grows in the Czech Republic, Slovakia, Austria, Hungary, Croatia, Serbia, and Romania. From the phytogeographic point of view, it can be classified as a Pannonian geoelement with overlaps to Transylvania and to the marginal parts of the eastern Mediterranean. Within the Czech Republic, its distribution range includes only the warmest and driest part of southern Moravia, with the northernmost site situated near the town of Vyškov. In southern Moravia, A. asplenifolia was confined to extrazonal habitats, mainly to islands of halophilous vegetation such as moist saline meadows (formerly used as pastures) and lowland fens rich in mineral nutrients, but most of the sites were destroyed. Out of six or seven localities preserved up to present, only two host vital populations.
Chromosome numbers are given for 16 taxa (and one interspecific hybrid) of Hieracium subgen. Pilosella originating from Central Europe: H. apatelium Nägeli et Peter (2n = 45), H. aurantiacum L. (2n = 36), H. bauhini Besser (2n = 36, 45, 54), H. brachiatum Bertol. ex DC. (2n = 45, 48, 63, 72), H. densiflorum Tausch (2n = 36), H. echioides Lumn. (2n = 18, 27, 36), H. floribundum Wimm. et Grab. (2n = 36, 45), H. glomeratum Froel. (2n = 36, 45), H. guthnickianum Hegetschw. (2n = 54), H. lactucella Wallr. (2n = 18), H. onegense (Norrl.) Norrl. (2n = 18), H. pilosella L. (2n = 36, 45, 54), H. piloselliflorum Nägeli et Peter (2n = 36, 45), H. piloselloides Vill. (2n = 36), H. rothianum Wallr. (2n = 36), H. schultesii F. W. Schultz (2n = 45), and the hybrid H. floribundum × H. aurantiacum (2n = 36). New chromosome numbers are reported for H. brachiatum and H. floribundum. The octoploid cytotype (2n = 72), recorded in H. brachiatum, is the highest ploidy level ever found in plants from the subgen. Pilosella originating from the field. Aneuploidy, rare in this subgenus in Europe, occurs in this hybridogenous species as well: it was recorded in one plant (2n = 48) collected in a hybrid swarm H. pilosella × H. bauhini. The breeding system in H. bauhini, H. brachiatum, H. densiflorum, H. echioides, H. pilosella, H. piloselloides, and H. rothianum was studied. The sexual reproduction of pentaploid H. pilosella is a new observation: it means an increase of diversity in possible reproduction modes of those cytotypes having odd chromosome numbers.
Chromosome numbers (ploidy levels) were recorded in the following 25 taxa of Hieracium subgen. Pilosella: H. arvicola Nägeli et Peter (2n = 45), H. aurantiacum L. (2n = 36, 45), H. bauhini Besser (2n = 36, 45), H. bifurcum M. Bieb. (2n = 45), H. brachiatum Bertol. ex DC. (2n = 36, 45), H. caespitosum Dumort. (2n = 36), H. cymosum L. (2n ~ 4x), H. densiflorum Tausch (2n = 36, ~ 4x), H. echioides Lumn. (2n = 18, 45), H. fallacinum F. W. Schultz (2n = 36, 45), H. floribundum Wimm. et Grab. (2n = 36, ~ 4x, 45,), H. glomeratum Froel. in DC. (2n = 45), H. iseranum Uechtr. (2n = 36), H. kalksburgense Wiesb. (2n ~ 5x), H. lactucella Wallr. (2n = 18), H. macranthum (Ten.) Ten. (2n = 18), H. onegense (Norrl.) Norrl. (2n = 18), H. pilosella L. (2n = 36, 45, 54), H. piloselliflorum Nägeli et Peter (2n = 45), H. pilosellinum F. W. Schultz (2n = 36, 45), H. piloselloides Vill. (2n = 27, 36, ~ 4x, 45, ~ 5x), H. pistoriense Nägeli et Peter (2n = 27), H. rothianum Wallr. (2n ~ 3x), H. schultesii F. W. Schultz (2n = 36, 45, ~ 5x), H. zizianum Tausch (2n = 27, 36, 54), and one hybrid, H. onegense × H. pilosella (2n = 36). Besides chromosome counts in root-tip meristems, flow cytometry was used to determine the DNA ploidy level in 83 samples of 9 species. The presence of a long marker chromosome was confirmed in tetraploid H. caespitosum and H. iseranum, in pentaploid H. glomeratum, and in both tetraploid and pentaploid H. floribundum. The documented mode of reproduction is sexual (H. densiflorum, H. echioides, H. piloselloides) and apomictic (H. brachiatum, H. floribundum, H. pilosellinum, H. piloselloides, H. rothianum, H. zizianum). Hieracium bifurcum and H. pistoriense are sterile. The chromosome number and/or mode of reproduction of H. bifurcum (almost sterile pentaploid), H. pilosellinum (apomictic pentaploid), H. piloselloides (apomictic triploid), H. pistoriense (sterile triploid), H. rothianum (apomictic triploid) and H. zizianum (apomictic triploid) are presented here for the first time. The sexual reproduction recorded in the pentaploid H. echioides is the second recorded case of this mode of reproduction in a pentaploid cytotype of Hieracium subgenus Pilosella. A previously unknown occurrence of H. pistoriense (H. macranthum – H. bauhini) in Slovakia is reported.
A taxonomic revision of Taraxacum sect. Leucantha Soest is presented. Species in this section are mainly characterized by the pale bordered and appressed outer involucral bracts, achenes covered with subsparse coarse spinules, thick cylindrical cone and a relatively short, thicker rostrum, and often white or pale yellowish flowers. They occur in subsaline wet meadows and steppe depressions over a large area including Mongolia, South Siberia, NE, N and W China, Tibet, the Western Himalayas, Tadzhikistan, Kyrgyzstan and E and NE Kazakhstan. Eighteen species are recognized, seven of them described as new: Taraxacum niveum from the Altai and Dzhungaria, T. candidatum centred in Ladakh, Tadzhikistan and Kyrgyzstan, T. album from Kyrgyzstan, T. flavidum from Mongolia and Transbaikalia, T. occultum from East Mongolia, T. virgineum from Ladakh, India, and T. inimitabile from Gobi-Altai, Mongolia. An analysis of syntypes of the names T. dealbatum Hand.-Mazz. and T. sinense Dahlstedt is given. For the safe interpretation of the name T. luridum, epitype was designated. All the species are agamospermous but sexuality and diploidy is documented for a few Transbaikalian plants of the section Leucantha.
The few attempts to produce artificial hybrids in the genus Hieracium s. str. have usually failed due to the use of polyploid parental taxa reproducing via agamospermy. Presented here for the first time are data on artificial hybridization in Hieracium s. str. which may help in understanding the microevolutionary processes resulting in the great morphological and genetic diversity in this genus. Diploid, sexually reproducing species (H. alpinum, H. pojoritense, H. transsilvanicum and two stable morphological types of H. umbellatum – of a low altitude and a high mountain type) were used as parent plants in experimental crosses. In most cases true hybrids, with intermediate morphology, were obtained. All the hybrids tested were diploid and produced a high amount of stainable pollen (65–92%). Hybrid progeny resulting from one cross exhibited a large range of morphological variation due to the combination of alleles from unrelated parental species. The percentage of welldeveloped achenes per capitulum, in capitula with at least one well-developed achene, in hybrids, ranged from 1.9 to 12.5% after free or controlled pollination, with an average of 4–5% per capitulum. Similar results (1.9–12.1%) were obtained from triple-cross hybrids. However, most of the capitula of hybrid progeny (either F1 or triple) were completely sterile after free or controlled pollination. Sterility is probably caused by genome incompatibility of unrelated parental taxa belonging to different sections. In two crosses, where strictly allogamous diploid plants of H. umbellatum (both morphotypes) were used as mother plants and F1 hybrids as pollen donors, some matroclinal progeny were obtained. This is a further example of the previously reported mentor effect. Diploid hybrids may be involved as pollen donors in gene flow as they produce uniformly sized and viable pollen. They are probably substantially less important as seed parents.
Six populations of Hieracium echioides subsp. echioides var. tauscheri from the Danube Basin between Bratislava and Budapest (locations: Balinka, Čenkov, Devín, Dorog, Győr, Pilis) were analysed using allozyme and karyological analysis. Five allozyme systems (EST, LAP, 6PGDH, PGM, and SKDH) were used to analyse the genetic structure of the examined populations. Analyses revealed low genetic variation both within- and among populations. Four multilocus allozyme phenotypes were detected; three populations (Čenkov, Devín and Győr) possessed phenotype I exclusively, while phenotype II was found only in the Balinka and Dorog populations. Two different phenotypes were found in the population of Pilis (phenotypes III and IV). However, due to the complex banding patterns generated for EST, allelic interpretationwas not possible, and the Balinka and Dorog populations appeared to possess different phenotypes. All populations proved to be tetraploid (2n = 36) and agamospermous. The geographic distribution pattern of the analysed populations (one allozyme phenotype at several isolated localities) may reflect a more common occurrence of the taxon in the past. Landscape changes, caused by changes in human management of the country, may have resulted in a loss of suitable localities, mainly open sandy habitats. These changes may have caused the reduction and fragmentation of H. *tauscheri habitat.
Variation in genome size in a particular taxonomic group can reflect different evolutionary processes including polyploidy, hybridization and natural selection but also neutral evolution. Using flow cytometry, karyology, ITS sequencing and field surveys, the causes of variation in genome size in the ecologically and morphologically diverse high-Andean genus Lasiocephalus (Asteraceae, Senecioneae) were examined. There was a 1.64-fold variation in holoploid genome size (C-values) among 189 samples belonging to 20 taxa. The most distinct was a group of plants with large genomes corresponding to DNA triploids. Disregarding the DNA triploids, the remaining samples exhibited a pronounced (up to 1.32-fold) and rather continuous variation. Plants with the smallest genomes most likely represent intergeneric hybrids with the closely related and sympatric Culcitium nivale, which has a smaller genome than Lasiocephalus. The variation in genome size in samples of diploid Lasiocephalus was strongly correlated with several environmental and life history traits (altitude, habitat and growth form). However, all these factors, as well as genome size itself, were correlated with phylogeny (main split into the so-called ‘forest’ and ‘páramo’ clades), which most probably represents the true cause of the differentiation in intrageneric genome size. In contrast, relationships between genome size and phylogeny were not apparent at lower divergence levels. Instead, here we suggest that ecological conditions have played a role in driving shifts in genome size between closely related species inhabiting different environments. Collectively, this study demonstrates that various evolutionary forces and processes have shaped the variation in genome size and indicates that there is a need for multi-approach analyses when searching for the causes and consequences of changes in genome size.
Chromosome numbers for 239 plants from 84 localities in the Czech Republic, Slovakia, Hungary, Germany and Poland are given. Most of the populations were pentaploid (2n = 45), while hexaploid (2n = 54) and tetraploid (2n = 36) populations were rarer. A long marker chromosome was observed in plants from 8 pentaploid populations. Tetraploid plants occurred mainly in Slovakia and Hungary. In the Czech Republic and Germany, most populations were pentaploid. Hexaploid populations (2n = 54) were rare but scattered over the entire study area. The co-occurrence of two different cytotypes was documented at 7 sites. Most tetraploids were fully sexual and only a few tetraploid plants from Poland were apomictic; pentaploid and hexaploid plants were apomictic. Two morphotypes of H. bauhini were distinguished: tetraploid and hexaploid plants from Slovakia and Hungary, and some hexaploid plants from the Czech Republic were assigned to the H. magyaricum group, while tetraploids and hexaploids from the Czech Republic and Poland plus all pentaploids belong to the H. bauhini group.
A taxonomic concept for the Hieracium nigrescens agg. (H. alpinum ≥ H. murorum) in the Western Carpathians is proposed. Three taxa at the species level are recognized, i.e. Hieracium jarzabczynum, H. mlinicae and H. vapenicanum. One new combination, Hieracium mlinicae (Hruby et Zahn) Chrtek f. et Mráz (H. nigrescens subsp. mlinicae Hruby et Zahn) is published. All taxa should be considered as endemic to the Western Carpathians (both the Polish and Slovakian parts). Detailed descriptions, drawings, lists of localities, distribution maps and determination key are provided along with a comparison with the last comprehensive account of the group (by Zahn 1936). Several lectotypes were chosen for the taxa recognized by Zahn within H. nigrescens s.l.