Foliar venation characteristics of Vaccinium sect. Macropelma and sect. Myrtillus (Ericaceae): a comparative analysis

Abstract

A suite of eight foliar venation characteristics from two closely related sections of Vaccinium L., sect. Macropelma Klotzsch and sect. Myrtillus Dumortier, were analyzed to assess the level of similarity between these sister sections, address the questionable classification of Vaccinium cereum (L.f) Forster, and assess the diagnostic ability of venation characteristics. Our analysis revealed no significant differences in foliar venation characteristics between V. cereum and the Hawaiian species from sect. Macropelma. In addition, all the leaves of V. cereum examined contained the attenuated extended bundle sheath system as found in other representatives from sect. Macropelma. Taximetric analysis showed that these quantitative foliar venation characters were diagnostic at the sectional level but not at the species level. A cluster analysis of 108 operational taxonomic units did separate the two sections but did not discriminate among the 12 individual species. However, a similar taximetric analysis using the character means for each species (for the eight foliar characters), which "smoothed out" the variation due to environmental plasticity, produced a dendrogram which closely resembled the currently accepted Vaccinium classification. Although further investigations into the constancy and reliability of foliar venation characters in the remaining sections of Vaccinium are desirable, our results clearly show that these quantitative vegetative foliar characters do have diagnostic value and can be utilized in taximetric analyses. Key words: Vaccinium, venation, leaf, systematics.