Abstract
H. florentinum All. was grown at N levels from 210-7.5 mg/liter. High N (210 mg/liter) stimulated root bud initiation and outgrowth. Buds were initiated next to lateral roots, which facilitated the counting of bud primordia in cleared roots. Bud outgrowth damaged cortical and epidermal cells. Fluorescence microscopy and histochemical tests for phenolics showed that root cells adjacent to emerging buds contained phenolic substances. In some roots a wound periderm formed in these regions. Phenolic substances probably prevent soil microorganisms from entering the root.