Variation in the Vigna lanceolata complex for traits of taxonomic, adaptive or agronomic interest

Abstract

Variation was assessed in the endemic Australian herbaceous legume, V. lanceolata Benth., by using an extensive collection of accessions that sampled a wide range of geographically dispersed collection sites. Attributes were evaluated under natural conditions at the time of collection and in field-grown plants in coastal south-eastern Queensland. Qualitative and quantitative measures were taken of traits reflecting plant habit, floral, vegetative and reproductive morphology, phenology and stress reactions. On the basis of visual assessment, accessions were subjectively allocated into seven previously reported morphotypes. Analysis of the variation confirmed that there were large differences among the putative morphotypes relative to that among the accessions within morphotypes. Significant correlations between accession means for some traits provided further evidence that V. lanceolata is not a homogeneous species and has differentiated into forms with sharply defined aggregations of distinctive traits. In addition, correlations between some traits and the latitude or longitude of collection implied a geographic component to the differentiation among accessions and morphotypes. In some instances, these changes were associated with adaptive responses, but in others may reflect chance occurrence. Cluster analysis confirmed the authenticity of the morphotype groups and provided information on the levels of affinity between them. It is concluded that V. lanceolata is a 'complex' of related taxa and that taxonomic revision is warranted. The information documented through the study provides the basis for that revision and also identifies several attributes of adaptive and/or agronomic significance.