Picea includes about 35 species of trees, three quarters of which are Eurasian and one quarter North American. We seek to clarify Picea phylogeny with sequences from three chloroplast DNA regions: trnK region (including the intron and matK gene), trnT-trnL intergenic spacer, and trnL intron plus trnL-trnF intergenic spacer. Our sample contains 27 Picea species - 13 from eastern Asia, three from central Asia, three from western Eurasia, and eight from North America - and outgroups Cathaya argyrophylla and Pinus thunbergii. Our data show only 0-1.4% sequence divergence within Picea,and parsimony analyses of separate regions do not yield well resolved phylogenetic trees. Trees from combined analyses, however, are more resolved and result in a monophyletic Picea. Western North American P. breweriana and P. sitchensis are the first branches within the genus, and the rest of the genus is divided into six clades. A clade of 11 mostly eastern Asian species is referred to as the P. abies clade because this species is sister to the remaining species of the group. Picea glauca plus two other North American species, P. engelmannii and P. mexicana, form a clade, and eastern European P. omorika is strongly linked to North American P. mariana and P. rubens. Central Asian P. schrenkiana and P. smithiana are sister taxa, and P. alcoquiana (P. bicolor) is isolated on our trees. A sixth clade has only 68% BS, is named for the Chinese P. purpurea, and is biogeographically quite heterogeneous with species from Japan ( P. maximowiczii and P. torano ), western Asia ( P. orientalis), and Mexico ( P. chihuahuana ). In their cpDNA restriction site study, Sigurgeirsson and Szmidt (1993, Nord. J. Bot. 13:233) found the same P. glauca and P. omorika clades but somewhat different species compositions for the P. abies and P. purpurea clades.

Key words: biogeography, chloroplast DNA, phylogeny, Picea