Hoya carandangiana, Hoya bicolensis, and Hoya camphorifolia (Apocynaceae) Species Delineation: Insights from Leaf Architecture

Jay T. Torrefiel; Inocencio E. Buot Jr.

Authors

Jay T. Torrefiel Institute of Biological Sciences, University of The Philippines, Los Bańos, College, Laguna, Philippines
Inocencio E. Buot Jr. Institute of Biological Sciences, University of The Philippines, Los Bańos, College, Laguna, Philippines

Keywords:

Hoya carandangiana, Hoya bicolensis, Hoya camphorifolia, leaf architecture, and taxonomy

Abstract

Three species of Hoya; H. carandangiana, H. bicolensis, and H. camphorifolia under the family Apocynaceae, have been studied and re-evaluated using leaf architecture to compare taxonomic markers. The three species seem superficially similar and consequently, controversial. This paper has carefully studied the three species and the results delineate them, proving they are three distinct species. In past decades there have been numerous studies, such as systematic studies and fossil (paleobotanical) studies, which utilized leaf architecture with the aim of resolving certain taxonomic issues. In this present study, leaf architectural characteristics have been utilized to examine the similarities and differences between the three Hoya species. Unifying leaf architectural characters were found, exhibited by the three Hoya species however; characters such as blade shape, blade class, base shape, apex shape, secondary vein category, tertiary vein category and course were found to delineate them. Cluster analysis was also carried out to illustrate relationships between the three Hoya species by using unweighted pair-group average (UPGMA) and single linkage (nearest neighbor). The results showed that Hoya carandangiana, Hoya bicolensis and Hoya camphorifolia are three distinct species, demonstrating that leaf architectural characters have the capacity to serve as good taxonomic markers.

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