This study was carried out at Suez CanalUniversity to report the production of tetraploid plants of snapdragon (Antirrhinum majus L.) and larkspur (Delphinium ajacis l.), with the ultimate aim of improving the ornamental qualities of these important floriculture plants. Chromosome doubling was achieved by the application of colchicine to either pre-soaked seed or to the apical meristems of young seedlings. Treatment of the ungerminated seed was the more efficient method in terms of numbers of tetraploid seedlings (up to 56.08% in Antirrhinum majus and 30.16% in Delphinium ajacis, as determined by chromosome counting of the root-tip nuclei). When colchicine was applied directly to the apical growing tip of cotyledon-stage seedlings, leaf and stem growth was temporarily affected but the plants eventually recovered. We conducted a preliminary screen for putative tetraploids based on the observation in other plant species of a correlation of stomatal size and count with ploidy. Stomatal studies revealed decrease in number with a concomitant increase in size of stomata across the lower leaf epidermis. These techniques confirmed that the highest number of tetraploid plants in Antirrhinum majus was observed by soaking seeds in 1% colchicine for 24 hours operating time, while 0.50% for 48 hours gave the same results in Delphinium ajacis. In spite of the fact that polyploidizationis a major driving force for plant genome evolution, results led to the conclusion that epigenetics evolved new morphological differences of the tetraploids included a more compact growth habit and shorter heights and darker leaves. These plants having a double chromosome number and nearly double DNA content. In addition, chlorophylls (a) and (b) were increased in ploidy incidence.