Study of Lyginia barbata across its distribution range in south-western Australia identified five distinctive morphotypes, viz. a tall-culmed, densely tufted fire-sensitive obligate seeder (S morphotype), a tall densely tufted fire-resistant resprouter (R1), a short flexuose-culmed, tufted resprouter (R2), a weakly clonal, semi-tufted resprouter (R3) and a short-culmed, widely spreading clonal form (R4). There was little variation within a morphotype between habitat locations and no evidence of intergrading of cohabiting morphotypes. Morphotype-specific differences were observed in culm height, rhizome morphology, culm density and spikelet morphology. Differences in reproductive biology related to the time of first reproduction in juvenile recruits, spikelet number per male and female culm, ovule number per female culm and seed : ovule ratio. Differences of a physiological nature were observed in seedling growth rates and proportional biomass (dry matter) allocations to culms, rhizomes, spikelets and seeds. Comparative quantitative scorings of the above features according to concepts of r- and K-selection rated the S form strongly r-selected, the R4 form equally strongly K-selected and the other forms (R1, R2 and R3) intermediate and with the R1 form possibly more r-selected than the others. It is suggested that the data provide a basis on which future taxonomic decisions regarding the taxon might be made.