Leaf architectural analysis of taxonomically ambiguous Hoya lacunosa Blume and Hoya krohniana Kloppenb. & Siar




Abstract. Scott HC, Buot JR IE. 2022. Leaf architectural analysis of taxonomically ambiguous Hoya lacunosa Blume and Hoya krohniana Kloppenb. & Siar. Biodiversitas 23: 2055-2065. The horticulturally important Hoya R.Br. species Hoya lacunosa Blume and Hoya krohniana Kloppenb. & Siar are often mistaken for each other because of their generally similar inflorescence morphology. Based on the hypothesis that leaf venation patterns are genetically fixed, leaf architectural analysis was done to determine the difference between these two taxonomically confusing species. Thirty fully expanded leaves were obtained per species from mature plants of H. lacunosa, H. krohniana and an outgroup, H. pubicorolla. Laminar and venation characters were analyzed using standard leaf architecture protocols. Results show that the main distinction lies in their laminar characters, particularly the base angle and base shape. H. lacunosa samples showed acute to obtuse base angles with cuneate and convex leaf bases, while H. krohniana were found to have obtuse reflex base angles with convex, cordate and rounded leaf bases. Analysis of venation characters shows no considerable difference between the patterns seen in H. lacunosa and the patterns observed in H. krohniana. Further investigation of higher vein orders is recommended. Initial comparison of H. lacunosa pollinaria with the photos of H. krohniana pollinaria from its type description show strikingly similar morphology; for this reason, we also recommend floral morphology comparisons, particularly pollinaria morphology to further establish the similarity and delineation of H. lacunosa and H. krohniana.


Aurigue, F. B. 2013. A Collection of Philippine Hoyas and Their Culture. Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD). Department of Science and Technology (DOST).
Baltazar, A. M. P., & Buot, I. E. 2019. Controversies on Hoya R.Br. Taxonomy. The Thailand Natural History Museum Journal, 13(1), 59–68.
Buot, I.E.Jr. 2020. Leaf Architecture as a Promising Tool in Confirming Identity of Confusing Plant Taxa. Journal of Nature Studies. 19(1), 134-143.
Cabactulan, D. D., Aurigue, F., Pimentel, R., Leon, M. D. D., Sahagun, J., & Rodda, M. 2019. Hoya of the Philippines, Part II: Hoya pulchra (Apocynaceae), a New Species from Southern Philippines. Annales Botanici Fennici, 56(1–3), 49. https://doi.org/10.5735/085.056.0109
Ellis, B., Daly, D. C., Hickey, L. J., Mitchell, J. D., Johnson, K. R., Wilf, P., & Wing, S. L. 2009. Manual of Leaf Architecture (Illustrated ed.). Comstock Publishing Associates.
Forster, P. I., & Liddle, D. J. 1991. VARIATION IN HOYA AUSTRALIS R. BR. EX TRAILL (ASCLEPIADACEAE). Austrobaileya, 3(3), 503–521. http://www.jstor.org/stable/41738789
Govaerts, R., Nic Lughadha, E., Black, N., Turner, R. & Paton, A. 2021. The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity. https://doi.org/10.1038/s41597-021-00997-6 Scientific Data 8: 215.
Gower, J. C. 1971. A general coefficient of similarity and some of its properties, Biometrics 27, 857–874.
Hickey, L. J. 1973. Classification of the Architecture of Dicotyledonous Leaves. American Journal of Botany, 60(1), 17–33. https://doi.org/10.1002/j.1537-2197.1973.tb10192.x
Hoya krohniana | IPNI. (n.d.). International Plant Names Index. Retrieved January 11, 2022, from https://www.ipni.org/n/77105117-1
Juhonewe, N. S., & Rodda, M. 2017. Contribution to a revision of Hoya (Apocynaceae: Asclepiadoideae) of Papuasia. Part I: ten new species, one new subspecies and one new combination. Gardens’ Bulletin Singapore, 69(1), 97–147. https://doi.org/10.26492/gbs69(1).2017-07
Jumawan, J. H., & Buot, I. E. 2016. Numerical taxonomic analysis in leaf architectural traits of some Hoya R.Br. species (Apocynaceae) from Philippines. Bangladesh Journal of Plant Taxonomy, 23(2), 199–207. https://doi.org/10.3329/bjpt.v23i2.30851
Kidyoo, M. 2012, April. Hoya mirabilis Kidyoo, a New Species of Hoya (Asclepiadaceae) from Western Thailand. Tropical Natural History, 12(1), 21–28. https://www.researchgate.net/publication/328462721_Hoya_mirabilis_Kidyoo_a_New_Species_of_Hoya_Asclepiadaceae_from_Western_Thailand
Kidyue, M., Boonkerd, T., Thaithong, O., & Seelanan, T. 2005, October. Numerical Taxonomy of the Hoya parasitica (Asclepiadaceae) complex in Thailand. The Natural History Journal of Chulalongkorn University, 5(2), 47–59.
Kloppenburg, R. D. 2004, September. Malaysian Hoya Species III. Robert Dale Kloppenburg (self-published). http://dalekloppenburg.blogspot.com/2014/06/malaysian-hoya-6.html
Kloppenburg, R. D., & Siar, S. 2009. Hoya krohniana Kloppenburg & Siar 2009. Fraterna, 22(4). http://www.international-hoya.org/publications.asp
Laga, H., Kurtek, S., Srivastava, A., Golzarian, M., & Miklavcic, S. J. 2012. A Riemannian Elastic Metric for Shape-Based Plant Leaf Classification. 2012 International Conference on Digital Image Computing Techniques and Applications (DICTA). https://doi.org/10.1109/dicta.2012.6411702
Lamb, A., Rodda, M., & Natural History Publications (Borneo). 2016. A Guide to Hoyas of Borneo. Natural History Publications (Borneo).
Laraño, A. A. P., & Buot Jr, I. E. 2010. Leaf Architecture of Selected Species of Malvaceae sensu APF and its Taxonomic Significance. Philippine Journal of Systematic Biology, 4(0). https://doi.org/10.3860/pjsb.v4i0.1563
Leaf Architecture Working Group. 1999. Manual of Leaf Architecture. Leaf Architecture Working Group, Department of Paleobiology, Smithsonian Institution.
Masungsong, L. A., Belarmino, M. M., & Buot JR, I. E. 2019. Delineation of the selected Cucumis L. species and accessions using leaf architecture characters. Biodiversitas Journal of Biological Diversity, 20(3), 629–635. https://doi.org/10.13057/biodiv/d200303
Medina, M. N., Amoroso, V., & Kloppenburg, R. 2016. Changes of leaf morphology of Hoya amorosoae from varying light exposure: Its implications to species description and taxonomy. Journal of Biodiversity and Environmental Sciences. 6663. 2222-3045.
Mouine, S., Yahiaoui, I., & Verroust-Blondet, A. 2013. Combining Leaf Salient Points and Leaf Contour Descriptions for Plant Species Recognition. Lecture Notes in Computer Science, 205–214. https://doi.org/10.1007/978-3-642-39094-4_24
Paguntalan, D. P., & Buot, I. E. 2019. Short Communication: Investigation of leaf architectural patterns: Implications in delineating taxonomically controversial Hoya merrillii Schlechter and Hoya quinquenervia Warburg. Biodiversitas Journal of Biological Diversity, 20(3), 833–839. https://doi.org/10.13057/biodiv/d200329
Plants of the World Online (POWO) 2021. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:77105117-1 Retrieved 03 December 2021
Rahayu, S., & Rodda, M. 2019. Hoya of Sumatra, an updated checklist, three new species, and a new subspecies. European Journal of Taxonomy, 508. https://doi.org/10.5852/ejt.2019.508
Roth-Nebelsick, A. 2001. Evolution and Function of Leaf Venation Architecture: A Review. Annals of Botany, 87(5), 553–566. https://doi.org/10.1006/anbo.2001.1391
Torrefiel, J. & Buot, I. E. Jr. 2017. Hoya carandangiana, Hoya bicolensis, and Hoya camphorifolia (Apocynaceae) Species Delineation: Insights from Leaf Architecture. The Thailand Natural History Museum Journal. 11. 35-44.
Vasco, A., Thadeo, M., Conover, M., & Daly, D. C. 2014. Preparation of samples for leaf architecture studies, a method for mounting cleared leaves. Applications in Plant Sciences, 2(9), 1400038. https://doi.org/10.3732/apps.1400038
Villareal, A. M. M., & Buot Jr., I. E. 2015. Leaf Architecture of Hoya incrassata Warb. and Hoya crassicaulis Elmer x Kloppenb. (Apocynaceae): Taxonomic Identification and Conservation Concerns. IAMURE International Journal of Ecology and Conservation, 15(1). https://doi.org/10.7718/ijec.v15i1.1002
Wäldchen, J., & Mäder, P. 2017. Plant Species Identification Using Computer Vision Techniques: A Systematic Literature Review. Archives of Computational Methods in Engineering, 25(2), 507–543. https://doi.org/10.1007/s11831-016-9206-z
Widiarsih, S., Siar, S., Lalusin, A., Carandang, J., & Borromeo, T. 2012. Genetic Diversity Assessment in Vegetative and Reproductive Characters of Hoya mindorensis Schlechter. Philippine Journal of Crop Science (PJCS), 37(3), 23–29.
Wilcox, A. R. 1973. Indices of Qualitative Variation and Political Measurement. The Western Political Quarterly 26, no. 2: 325–343. doi:10.2307/446831.
World Flora Online, 2021. Hoya krohniana Kloppenb. & Siar. Published on the Internet; http://www.worldfloraonline.org/taxon/wfo-0000746580. Accessed on: 03 Dec 2021
Zhao, C., Chan, S. S., Cham, W. K., & Chu, L. 2015. Plant identification using leaf shapes—A pattern counting approach. Pattern Recognition, 48(10), 3203–3215. https://doi.org/10.1016/j.patcog.2015.04.004

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