Polyploid induction in vitro using colchicine and oryzalin on Hebe ‘Oratia Beauty’: Production and characterization of the vegetative traits

•Tetraploids of Hebe were induced in vitro with colchicine and oryzalin.•Oryzalin was more efficient than colchicine and both chemicals produced mixoploids.•Stomatal density was lower and stomatal length was higher in tetraploids.•Tetraploids had thicker stems, were shorter and had fewer nodes than diploids.