Chromosome numbers of some North American Arctic and BorealSalix

摘要

Chromosome numbers are reported for 12 native North American species ofSalixand one natural hybrid. The arctic speciesSalix alaxensisvar.alaxensis, S. fuscescens, S. ovalifoliavar.ovalifolia, S. phlebophylla, andS. reticulataand the boreal speciesS. arbusculoidesare diploids, 2nensp;=ensp;38. Tetraploid counts, 2nensp;=ensp;76, are reported for the arcticS. planifoliassp.pulchra. Taxa with more than one chromosome number includeS. planifoliassp.planifoliaandS. pedicellaris, each of which has tetraploid and triploid levels;S. arcticas.l., which is tetraploid in the eastern American arctic and hexaploid in the Alaska and Eurasian arctic; andS. athabascensiswith triploid, tetraploid, and hexaploid levels. Intra-population variation in chromosome number is reported forS. glaucain which tetraploids, pentaploids, and hexaploids occur in a single Alaskan population.