Fibres and Fibre-sclereids in Wild-typeArabidopsis thaliana

Examination of the fibre system in roots and shoots of Arabidopsis thaliana (L.) Heynh. revealed three types of fibres, distinguished according to their site of differentiation: (1) short fibre-sclereids in the secondary phloem of roots and shoots at the rosette level; (2) long fibres in the secondary xylem of the main root; and (3) very long fibres in the xylem of the inflorescence stems. These three types are in addition to the small number of primary phloem fibres that are formed even in small A. thaliana individuals. These findings provide a basis for the use of Arabidopsis thaliana as a model system to study the processes leading to fibre differentiation in dicotyledons.