Hoary cress reproduction in a sagebrush ecosystem

Field studies were undertaken to evaluate hoary cress (Cardaria draba (L.) Desv.) reproduction and spread in a sagebrush ecosystem. Hoary cress germin ation, emergence, and survival were restricted to moist environments. These conditions occurred 2 out of 8 years. Hoary cress germination under field conditions was greatest on toe slope positions and areas of soil disturbanc e. Number of sheets varied annually for established hoary cress populations . Shoot propagation was reduced when early spring growth was followed by fr ost or drought. Shoot numbers were increased when spring growth was delayed and warm, moist growing conditions occurred in May. Seed reproduction did not increase plant density in monitored populations. Established population s relied upon vegetative reproduction to sequester resources and increase p lant density.