J Syst Evol

• Research Articles •    

Breeding systems and phylogeny in Poa , with special attention to Northeast Asia: The problem of Poa shumushuensis and sect. Nivicolae (Poaceae)

Robert J. Soreng1*, Marina V. Olonova2, Nina S. Probatova3, and Lynn J. Gillespie4   

  1. 1Dept. Botany, Smithsonian Institution, Washington D.C. 20013-7012, USA

    2Tomsk State University, Biological Institute, Tomsk 634050, Russia

    3Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far East Branch of the Russian Academy of Sciences, Vladivostok, 690022, Russia

    4Research and Collections, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada

  • Received:2019-08-23 Accepted:2020-06-04 Online:2020-06-09

Abstract:

Poa sect. Poa subsect. Nivicolae (Prob.) Tzvelev was circumscribed to include four species of the Soviet Union: Poa shumushuensis, Poa caucasica, Poa irkutica , and Poa veresczaginii . Bayesian phylogenetic analyses of plastid and nuclear‐ribosomal DNA revealed that it is polyphyletic, none of these species are closely related. Poa shumushuensis , type of sect. Nivicolae , or its ancestor, likely displayed the nrDNA genotype characteristic of the higher polyploid P . sect. Malacanthae . Genotype codes are designated for each species: Hx , C c , Php , and Shp . Poa sect. Nivicolae s.s. is restricted to P. shumushuensis ; P . sect. Irkuticae is restricted to P. irkutica ; P. caucasica is moved to P . subg. & sect. Caucasicae nov.; and P . sect. Dschungaricae is resurrected for P. veresczaginii and two other species. Although diclinous breeding systems are known in many western hemisphere species of Poa , dicliny is infrequent and little studied in Asian Poa. Poa shumushuensis is judged to be either sequentially gynomonoecious or gynodioecious. A ratio of 2 perfect‐, to 2 mixed‐, to 1 pistillate‐flowered inflorescences from different plants in P. shumushuensis is suggestive of a recessive allele for stamen suppression, and this is associated with subtle sexual‐dimorphism. Poa irkutica is diclinous with a breeding system between simple gynomonoecy and sequential gynomonoecy; P. caucasica is perfectly flowered; and P. veresczaginii has infrequent abortive anthers, indicative of limited dicliny, or sterility for other reasons possibly related to its reticulate origin. In total, 23 Asian species are here reported to be diclinous and their breeding systems are characterized. A lectotype is designated for P. fauriei .