Two new triploid hybrids in Equisetum subgenus Hippochaete for Central Europe and notes on the taxonomic value of Equisetum trachyodon forma Fuchsii (Equisetaceae, Pteridophyta)
Lubienski, Marcus; Bennert, H. Wilfried; Körner, Simone
Only recently, three genomically different triploid taxa were discovered in Equisetum subgen. Hippochaete. For one of these an older name exists (E. ×alsaticum). The two others are described as E. ×ascendens and E. ×geissertii. E. ×ascendens is morphologically close to E. hyemale and probably possesses two genomes of E. hyemale and a third one of E. ramosissimum, while E. ×geissertii contains one chromosome set of each of the three Hippochaete species indigenous to Central Europe. The morphology of these triploids, in particular their stem micromorphology, is discussed and compared with the parents and the three diploid hybrids (E. ×meridionale, E. ×moorei, and E. ×trachyodon). A detailed list of characters including non-morphological traits is presented as a tool to facilitate determination. The distribution of E. ×ascendens and E. ×geissertii is illustrated by distribution maps and is discussed making reference to the diploid hybrid E. ×meridionale. Revision of specimens from the type locality of “Equisetum trachyodon forma Fuchsii” revealed them to be conspecific with E. ×meridionale.