Calluna vulgaris(L.) Hull possesses a root system with fine rootlets, usually called «hair roots». Longitudinal median sections of growing hair roots show the presence of an apical meristem consisting of separate initials (specific initials for central cylinder and cortex, a common initial for epidermal and cap cells organized as a dermatocalyptrogen) and a simple differentiated zone. The general histological organization is characteristic of Dicotyledons, even though the reduced number of initials and the total size of the hair root lead to a «miniaturized» root. The differentiated zone lacks root hairs and the cortical cells quickly collapse before vascularization takes place. Some ultrastructural features of cellular differentation are noteworthy: nuclear changes, versatility of dictyosomes, production of mucilage, and deposition of tannins in the epidermal and cortical cells.