Panarctic Flora


3426 Poa L.


Notes: Relationships among the different parts of this large genus are now becoming more clear due to recent phylogenetic studies based on cpDNA and ITS sequences (Gillespie and Soreng 2005; Gillespie et al. 2008). Poa has been much discussed among the PAF collaborators, mainly Aiken, Elven, Yurtsev, and Tzvelev, in some aspects also Gillespie and Soreng. The three main points have been: (1) Treatment as series of species or as races in the large and mainly agamospermous (and partly viviparous) complexes of P. arctica s. lat. and P. pratensis s. lat. and their relatives. (2) The relevance of several Russian species in groups where non-Russian authors recognize only one or a few polymorphic species, that is, in the relationships of the at least partly agamospermous P. glauca, P. nemoralis, and P. palustris. (3) Acceptance or non-acceptance of assumed hybrid origins of some plants. We have the opportunity, for plants present in North America, to compare the opinions of Tzvelev (several treatments) with those of Soreng et al. (2003) and Soreng (2007). The evaluation has been hampered by lack of cross-comparison of Russian and non-Russian material and by some important publications (especially Probatova's) only being available in Russian. The recent phylogenetic works only rarely throw any light on these questions mainly connected to assumed recently evolved differences and taxa not reflected in more conservative DNA sequences.

Higher Taxa