Abstract

St. Augustinegrass [S. secundatum (Walt.) Kuntze] varies genetically in many morphological and agronomic traits.  The objective of this study was to classify a sample of St. Augustinegrass genotypes.  By distinguishing natural groups, a classification would be useful in summarizing the genetic variation.  A collection of Stenotaphrum genotypes was classified on morphological and performance traits from field plots and pots.  Clustering was based on a standardized data set of 26 characters measured on 94 genotypes.  Five groups of St. Augustinegrass were recognized from the cluster diagram.  In order of distinctiveness and internal similarity, the groups included:  Gulf Coast, Bitterblue, Dwarf, Roselawn-Floratam, and Miscellaneous.  The mean coefficient of determination for 26 characters was 51%.  Over 85% of the classified genotypes could be identified to a specific group by suing a key.  The taxonomic groups appeared to be natural and corresponded to several distinctive patterns, including geography, chromosome number, and adaptation.  Economic characters such as rate of coverage, gray leafspot resistance, blueness of leaves, and overall size differed for various groups, and the classification can serve as a framework of orientation for a breeding program.