Geleznowia Turcz. (Rutaceae) is a monotypic but morphologically variable genus endemic to Western Australia. Small and large forms can be recognised in the field by flower size and abundance, and leaf size. Between these two forms are a series of populations exhibiting intermediate and/or mixed characters. Uni- and multivariate analyses were undertaken of 17 adult leaf and floral characters from 17 populations (20 sites) representing the two forms and the intermediate populations from across the species’ range. Univariate analyses between populations showed the small form exhibited significantly shorter leaves, bracts and sepals than the intermediate populations and the large form as well as more rounded leaves. Discriminant analysis of the 371 individuals correctly classified 90.84% of the plants, with leaf and bract characters and ratios between floral characters contributing most to separation of the small form from all other plants. Non-metric multidimensional scaling and cluster analyses also clearly separated the small form from the other forms. Consistent placement of the small form at Pleshkes with the intermediate populations and large form further supports allozyme evidence that gene flow and introgression is/has occurred within this population. The possibility of hybridisation within the genus does present some difficulties for systematic clarification.