Phenotypic Variability in Life History Traits and Phenology of Field Populations of Cardamine flexuosa and C. fallax (Cruciferae) in Honshu, Japan

Abstract

Abstract Variability in life history traits and phenology of field populations of Cardamine flexuosa and C. fallax was investigated. C. flexuosa is an annual that typically grows all year around and occurs as a weed in cultivated fields such as paddy fields, crop gardens and orchards. C. fallax is a typical winter‐green annual that mainly grows along the roadside on foothills. Differences in growth form of both species corresponded to variations in habitat conditions. Plants of paddy field populations of C. flexuosa normally possess many basal branches, while those of orchard populations of C. flexuosa typically have an erect growth form with few basal branches. C. fallax also possesses a typical erect growth form. Other life history traits (e.g., individual plant biomass and reproductive traits) of both species were highly variable both within and between populations. In C. flexuosa, seasonal differences were also found in flowering and fruiting performance. Synchronous flowering of all plants was observed in spring populations, while partial flowering occurred in summer‐autumn populations. Differences in the size class structure of plants in the autumn appeared to be caused by different cultivation schedules for crop plants in the fields. C. fallax, in contrast, possesses a rather fixed seasonal growth cycle as a typical winter‐green annual with a synchronized flowering in spring.