Zonation and regulation of old pasture populations of Hieracium floribundum

Abstract

Colonies of the perennial Hieracium floribundum Wimm. and Grab, had four zones, identified by the density of the rosettes. Belts of sod were analyzed to determine the characteristics of these zones in a pasture which had not been grazed for 5 years. The advancing outer zone consisted of widely spaced rosettes that were less than 2 years old. These rosettes had short rhizomes and large leaves, reproduced by stolons, and flowered abundantly, producing numerous heads per inflorescence. In the central zone, which had the highest density, the rosettes were more than 2 years old, had long rhizomes and small leaves, and did not flower. Seedling numbers were insignificant in all zones. In this species stolons are produced only on plants that have flowered. At high densities curtailment of population growth resulted from reduced flower production and the number of associated stolons initiated per flowering plant.