New species of Taraxacum native to central Europe

Further taxonomic exploration of the genus Taraxacum in central Europe was carried out to update the new identification key to the Czech flora. Within three relatively well explored groups new species were revealed; they are described as Taraxacum aspectabile (T. sect. Erythrosperma), T. clandestinum (T. sect. Palustria) and T. sparsum (T. sect. Celtica s. lat.). Taraxacum aspectabile is known to occur in Austria, Bavaria, Czech Republic and Slovakia, usually in grassland growing on alluvial sands but also in other sandy habitats. It is distinct in having deep castaneous-brown to greyish dark brown achenes with a short cone, and numerous triangular lateral leaf segments. Taraxacum clandestinum is confined to a few sites in the Příbram district, south-central Bohemia and is endemic to Bohemia. This rare species is characterized by a robust involucre with numerous but non-imbricate, ovate to broadly ovate outer phyllaries, the absence of pollen, yellow stigmas, and slender, long achenes with a thin, long cylindrical cone. Taraxacum sparsum is known from numerous localities, all in the lowland eastern part of the Bohemian Chalk Plateau. Its distinctive features include leaves with scattered conspicuous brown-purple spots above, the midvein finely striate purplish adaxially, outer phyllaries patent to patent-arcuate, abaxially dark olivaceous brownish green with a narrow white border, and a relatively thick, ± densely and shortly spinulose achene body, subabrutly narrowing into a short, conical cone. Taraxacum sparsum is a marginal member of T. sect. Celtica, with some resemblance to members of the section Naevosa. All of these species are polyploid agamosperms.