Cytotaxonomic observations on North American Festuca (Poaceae)

Abstract

The presence of B chromosomes is reported in Festuca altaica Trin., where a plant with relatively wide and often flat leaves had a chromosome number of 2n = 4x = 28; an adjacent plant, with conspicuously narrow and tightly rolled leaves, had 2n = 4x = 28 + 2B chromosomes. A first chromosome count of 2n = 42 is reported for Festuca rubra L. ssp. densiuscula (Hackel) Piper, along with observations on the nomenclature and morphology of this west coast subspecies. A first chromosome count for a North American plant of Festuca brevissima Jurtzev is 2n = 14. Collections made in northern Yukon were compared with the type borrowed from Leningrad and with the distribution of this species relative to the other North American diploid Festuca, Festuca aggr. auriculata Drob. A collection of Festuca brachyphylla Schultes from northern Yukon had a chromosome number of 2n = 42, and unusual morphology and phenology were interpreted as the result of a snow patch habitat. A second record for Festuca dasyclada Hackel ex. Beal of a chromosome number of 2n = 28 and justifications for keeping this species in Festuca are presented. Key words: Poaceae, North American, Festuca, chromosomes, morphology, nomenclature.