The biology ofStellaria longipes(Caryophyllaceae)

Abstract

During the past 30 years of research on Stellaria longipes Goldie, much has been learned about the taxonomy, cytology, reproductive biology, genetic variation, and phenotypic plasticity of this highly successful, circumpolar species. The conclusion that a S. longipes complex exists where two diploid progenitors ( Stellaria longifolia Muhl. (2n = 26) and Stellaria porsildii Chinnappa (2n = 26)) hybridized to produce polyploid S. longipes (2n = 52, 2n = 78, 2n = 104) was determined following extensive cytological and morphological studies. Interspecific hybridization is also common with S. borealis (2n = 52). The genetic variation and phenotypic plasticity contributing to the population differentiation within the S. longipes complex was investigated using isozyme, RFLP, and RAPD analyses, and comparative morphological studies. In later years, the focus shifted to elucidating the physiological and molecular aspects regulating the stem elongation plasticity observed in response to different temperatures, photoperiods, and different red/far red ratios. The roles of the phytohormones, ethylene, gibberellins, and abscisic acid were investigated in alpine and prairie ecotypes of S. longipes, and the phytochrome multigene family members were cloned. The presence of multigene families and a complex phytohormone interaction are postulated to underlie the extensive phenotypic plasticity observed in S. longipes.