Hybridization between plant species occurs frequently but hybrids are often restricted to ecotones or disturbed habitats. In this study we show that introgressive hybrids between the tetraploid Viola riviniana and the diploid V. reichenbachiana invaded pine forests of the Dübener Heide (central Germany), an area affected by calcareous pollutants. The spread of these violet populations was correlated with the impact of pollution on habitat conditions. We compared morphology, cytology and random amplified polymorphic DNA (RAPD) bands among six Viola populations from the Dübener Heide and three populations of each pure species. RAPD analysis using 12 primers revealed 141 scorable bands. We considered bands as species specific if they occurred in at least 75% of the plants in one pure violet species but in none of the other. Seven bands were specific to V. riviniana and 11 bands were specific to V. reichenbachiana. Two plants of a V. reichenbachiana population were identified as hybrids. Of the Viola populations from the Dübener Heide, one was diploid and could be classified as V. reichenbachiana by morphology and RAPD markers. However, the majority of the Dübener Heide populations were tetraploid, and of a more variable morphology than V. riviniana and V. reichenbachiana, showing different combinations of intermediate characters, characters of the pure species and extreme characters. Despite their overall genetic similarity to V. riviniana, these plants could be identified as introgressive hybrids between V. riviniana and V. reichenbachiana by species‐specific RAPD bands. Therefore, we propose that recurrent hybridization and backcrossing resulted in novel genotypes adapted to the changed environment of polluted pine forests.

No abstract

Puccinellia fontana wird aufgrund ihrer Merkmalskombination und ihres sympatrischen Vorkommens mit P. distans als eigenständige Art bewertet und neu kombiniert. Erstmals werden Vorkommen in Deutschland nachgewiesen (Hessen, Rheinland-Pfalz, ehemals auch Saarland). P. fontana wird nicht als Neophyt, sondern als indigene und in Deutschland gefährdete Art gesehen. Die Merkmale zur Abgrenzung gegen P. distans werden dargestellt.

The patterns of morphological variation and distribution of the rare Central European endemic Spergularia echinosperma were investigated. Morphometric analyses revealed the existence of two distinct morphotypes differing each other mainly in seed color, which is either brown or black. Other differences are in density of the seed surface papillae, height and shape of the papillae, seed width, pedicel/capsule and internode/leaf ratios, and leaf length. A geographic separation of the morphotypes also exists. The black-seeded morphotype occurred nearly exclusively in drained fishponds in the south-western part of the Czech Republic, the brown-seeded morphotype was found in drained fishponds in the eastern part of the Czech Republic and in alluvial pools and river deposits of the Elbe River (Germany). We hypothesize that the black-seeded morphotype may have been indigenous in former natural lakes which were widespread in the SW-Czech Republic and they were frequently transformed into fishponds. The brown-seeded morphotype may have its origin in river alluvia of the Elbe (Germany) and possibly also of other rivers in the Czech Republic. Since the two morphotypes are morphologically and geographically well separated, we propose to describe the brown-seeded morphotype as a new subspecies for science, S. echinosperma subsp. albensis subsp. nov.

Panicum riparium wurde 2002 als neoindigene Art aus Deutschland neu beschrieben. Die Merkmale der Art werden kritisch untersucht und mit denen von P. capillare verglichen. Eine Karte zeigt erstmals die bislang bekannte Verbreitung von P. riparium in Europa. Es wurden historische Herbarbelege gefunden, die bis in das 18. Jahrhundert zurückreichen. Ein Merkmalsvergleich bestätigt die weitgehende Übereinstimmung mit amerikanischen Pflanzen. Eine taxonomische Klärung der amerikanischen Sippen des P.-capillare-Aggregats lässt keine Zweifel: die Merkmale des P. riparium sind weitgehend identisch mit denen des P. barbipulvinatum Nash. P. riparium ist somit in die Synonymie dieser Art zu stellen.