Data

Gonçalves, Ana Carla, Ouhammoud, Ahmed, Amirouche, Rachid, Santos, Conceição, Figueiredo, Estrela & Silveira, Paulo, 2023, A taxonomic revision of Calendula (Asteraceae) in Morocco, including some taxa from Algeria and Tunisia, Phytotaxa 605 (1), pp. 1-83 : 7

Data analysis

Morphological data were subjected to one-way analysis of variance to determine if there were significant differences between taxa for each character measured. For normally distributed and homoscedastic variables, t- test (between two groups) or One-way ANOVA (between more than two groups) were performed. When normality and homoscedasticity were not achieved, Mann-Whitney test (between two groups) and Kruskal-Wallis One-way ANOVA on ranks (between more than two groups) were used instead. Some taxa were excluded from the analysis of variance because of the scarcity of samples on some variables (e.g. leaf thickness or head diameter). Boxplots containing medians and percentiles of each character within species and subspecies were prepared. The most discriminant characters were used to perform the multivariate analysis and to build the identification keys. Principal component analysis (PCA) was used to evaluate the morphological variations among taxa. All statistical analyses were performed using the R programme (R Development Core Team 2010), except for PCA, which was performed with StatistiXL (Broadway – Nedlands, AUS).