<p dir="ltr">Data from a common garden experiment with invasive <i>Erythranthe guttata</i> populations in Canterbury, New Zealand. The experiment compared upland and lowland origin <i>E. guttata</i> populations grown in two gardens (a lowland garden at the University of Canterbury and an upland garden at the Cass Field Station) and at two nutrient levels (given as Osmocote fertiliser applied to meet nitrogen levels of 10g/m<sup>2</sup>/year and 30g/m<sup>2</sup>/year).<br><br>Data includes measures of dry weight, flower number, flowering start and end date, bloom period, flower width, length, height, and herkogamy, leaf and stem anthocyanin level, leaf length and width, height, photosynthetic rate, seed mass per pod, seed number, and average seed mass.<br><br>The second data set covers earlier observations of flower visitors to <i>E. guttata</i> populations in the field. Multiple patches of 50-70 flowers were observed in 15 minutes blocks throughout the day, and the number and basic taxonomic group of insects entering the corolla tube recorded. The Lewis Pass area data is likely to be an outlier, and only one site in the area could be visited.</p>