Environmental conditions can influence epigenetic variability of clonal organisms. These environmentally induced changes have potential to persist in following generations. In theory, this transgenerational memory could allow clonal (and especially apomictic) plants to partly compensate reduced genetic variability and could enhance adaptative ability of apomictic populations. According to Muller's ratchet model, asexual organisms amass deleterious mutations, which could lead to their extinction. Possible transgenerational memory could partly compensate for this. It could also account for longtime survivorship of asexual organisms in environment. This thesis deals with transgenerational memory of triploid apomictic populations of Hieracium alpinum, with completely missing sexuality and thus genetically uniform offspring. Transgenerational effect in Hieracium alpinum was studied on clonal lineages originated from 5 populations (Norway, Austria, Bosnia and Herzegovina and Slovakia). Seeds were planted in cultivation experiment I in 3 treatments (control, added nutrients, added salicylic acid) and vegetative and generative traits were measured. Plants responded to nutrient addition but not to salicylic acid. Treatment with nutrient addition increased biomass, number of leaves and SLA (specific leaf...