Ecological life history of the facultative woodland biennial Arabis laevigata variety laevigata (Brassicaceae): Reproductive phenology and fecundity

Abstract

We investigated reproductive phenology and fecundity in a population of the facultative biennial Arabis laevigata var. laevigata over a 2-year period in its rocky deciduous woodland habitat in northcentral Kentucky, USA. In contrast to most facultative biennials, A. laevigata grows in a habitat that may remain stable for a long period of time. Bolting (flower stalk elongation) occurred in March, anthesis peaked in mid April, and seeds matured in June/July. Probability of bolting increased with rosette size, which was highly correlated with number of seeds produced. Only 150 of 233 (64.4%) bolted plants monitored in 1986 and 1987 survived and produced seeds. Adults in 1987 produced taller flower stalks, more siliques per plant, longer siliques, and more seeds per plant than did adults in 1986. Arabis laevigata is similar to other facultative biennials in that onset of reproduction is size-dependent, not age-dependent, and fecundity is positively correlated with rosette size at time of reproduction.