Life history variation in blue flax (Linum perenne: Linaceae): seed germination phenology

Abstract

Linum perenne L. is a nonclonal perennial herb widely distributed across a range of habitats. Variation in seed germination patterns was examined for 21 Intermountain collections and for the commercial cultivar ‘Appar’. Collections from sites with long, snowy winters were largely dormant at harvest and responded positively to chilling. Collections from middle elevation sagebrush‐grassland sites were generally nondormant and contained a fraction induced into secondary dormancy by chilling. Collections from palouse prairie and pinyon‐juniper sites were generally nondormant and unaffected by chilling, as was ‘Appar’. When seeds of contrasting populations were planted in seed retrieval experiments at low, middle, and high elevation sites, their field germination phenology was predictable from laboratory experiments. In common garden experiments, there were significant among‐sibship differences in germination for each garden‐grown wild accession but not for ‘Appar’, suggesting that differences both among and within populations may be genetically based. Garden‐grown seeds were generally less dormant than wild‐collected seeds, possibly because of selection during propagation. Results demonstrated the existence of ecologically relevant among‐population and within‐population variation in germination phenology for blue flax. Seeds of high‐montane populations are spring‐emerging and have little provision for between‐year carryover. Populations from lower elevation habitats with less predictable weather have seeds with contrasting germination patterns, allowing for emergence in both fall and spring as well as for seed bank carryover. ‘Appar’ seeds lack these predictive and carryover mechanisms.