Multivariate and cladistic analyses of the purple-flowered species ofErysimum (Cruciferae) from the Iberian Peninsula

Abstract

A taxonomically difficult purple-flowered group within the genusErysimum, restricted to the Iberian Peninsula, is analyzed by multivariate and cladistic analyses. 51 specimens have been scored for 14 characters. Both principal components and discriminant analyses provide support to the recognition of the five species considered by the author, namelyE. linifolium, E. lagascae, E. baeticum, E. popovii, andE. cazorlense. Cladistic analysis, using 7 characters resulted in a single most parsimonious cladogram containing no homoplasies. The pattern of morphologic divergence follows a clear NW.-SE. trend, which is congruent with the topology of the cladogram. This trend significantly affects growth-form as well as fruit characters, both providing the main grounds for species recognition. The different behavior and significance of several characters in both kinds of analysis is discussed. The co-occurrence of morphologically similar individuals differing in the flower color is discussed, too. Possible explanations for this phenomenon involve hybridization in a wide sense or, alternatively, rejecting the assumption of monophyly for the group.