Morpho-anatomical characterization of Rhododendron subsessile Rendle, an endangered species of the Cordillera Central Range, Philippines

Abstract

Conservation of endangered plant species requires a prerequisite basic knowledge of their taxonomy and ecology. Unfortunately in the Cordillera Central Range, several species have not been studied, even though this area harbors a unique type of vegetation not found in other parts of the Philippines. This study documents the morpho-anatomical characteristics of Rhododendron subsessile Rendle, one of the unique and endangered flora in the area. The species exhibits a morphology typical of plants in high elevations, being a hardy shrub with small tough leaves, and showy pink flowers that rival those of commercial rhododendron species. New findings on the species morphology include a variable number of corolla lobes, stamens and a description of its fruits and seeds. The anatomical features of the species are reported here for the first time. The plant exhibits a typical dicot anatomy with dorsiventral leaves, woody stem and root system with the usual arrangement of periderm followed by secondary phloem, vascular cambium, secondary xylem with vessel elements and pith (in the case of the stem). A unique characteristic was identified as the biseriate upper epidermis of the leaf. Documenting the morphological and anatomical features of the species should prove valuable as input baseline information in formulating measures for its conservation.

Keywords

Taxonomy / Biodiversity conservation / Biseriate epidermis / Variable stamens

References

[1] Ayomipo AT, Johnson AA. Petiole anatomy of the genus Basella in South Western Nigeria. J Plant Sci, 2015, 10(1): 35-41.

[2] Bell AD. Plant form. An illustrated guide to flowering plant morphology, 1991, New York: Oxford University Press.

[3] Bell AD. Plant form: an illustrated guide to flowering plant morphology, 2008 2 New York: Oxford University Press.

[4] Buot IE Jr, Okitsu S. Leaf size zonation pattern of woody species along an altitudinal gradient on Mt. Pulog, Philippines. Plant Ecol, 1999, 145: 197-208.

[5] Chamberlain DF, Rae SJ. A revision of Rhododendron IV subgenus Tsutsusi. Edinb J Bot, 1990 47 2 127

[6] Fahn A. Plant anatomy, 1982 3 Oxford: Pergamon Press Ltd. 544

[7] Fernando ES, Co LL, Lagunzad DA, Gruezo WS, Barcelona JP, Madulid DA, Lapis AB, Texon GI, Manila AC, Zamora PM. Threatened plants of the Philippines: a preliminary assessment. Asia Life Sci, 2008, 3: 1-52.

[8] Gibbs D, Chamberlain D, Argent G. The red list of rhododendrons, 2011, Richmond: Botanic Gardens Conservation International.

[9] Haupt AW. Plant morphology, 1953, New York: McGraw Hill Book Company Inc 445

[10] Kores P. Notes on the genus Rhododendron (Ericaceae) in Papua New Guinea. Blumea, 1984, 30: 45-49.

[11] Leach DG. Rhododendrons of the world and how to grow them, 1961, New York: Charles Scribners Sons 544

[12] Merev N, Yavuz H. Ecological wood anatomy of Turkish Rhododendron L. (Ericaceae). Intraspecific variation. Turk J Bot, 2000, 24: 227-237.

[13] Metcalf CR, Chalk L (1950) Anatomy of dicotyledons. https://archive.org/details/anatomyofthedico033552mbp. Accessed 17 May 19

[14] Murphy GEP, Romanuk TN. Data gaps in anthropogenically driven local-scale species richness change studies across the Earth’s terrestrial biomes. Ecol Evol, 2016, 6(9): 2938-2947.

[15] Napaldet JT. Morpho-anatomical characterization of Benguet lily (Lilium philippinense Baker). Thail Nat Hist Mus J, 2017, 11(2): 47-56.

[16] Pancho JV, Gruezo WS. Vascular flora of mount makiling and vicinity (Luzon: Philippines), part 1. Kalikasan. The Philippine Journal of Biology Suppl 1, 1983, Manila: Kalikasan Press.

[17] Pancho JV, Gruezo WS (2006) Vascular flora of Mount Makiling and vicinity (Luzon: Philippines) Part 2. National Academy of Science and Technology (NAST) Philippines, Department of Science and Technology, Bicutan, Taguig City and Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Banos, Laguna, Philippines

[18] Pancho JV, Gruezo WS. Vascular flora of Mount Makiling and vicinity (Luzon: philippines) Part 3. Philipp Agric Sci, 2009, 92(suppl 1): S1-S496.

[19] Pancho JV, Gruezo WS (2012) Vascular flora of Mount Makiling and vicinity (Luzon: Philippines) Part 4. National Academy of Science and Technology (NAST) Philippines, Department of Science and Technology, Bicutan, Taguig City and Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Banos, College, Laguna, Philippines

[20] Pelser PB, Barcelona JF, Nickrent DL (eds.) (2011) onwards. Co’s Digital Flora of the Philippines. www.philippineplants.org. Accessed 06 Aug. 2019

[21] Prateeksha L (n.d.) Arrangements of tissues in leaves/plants. http://www.biologydiscussion.com/leaf/arrangements-of-tissues-in-leaves-plants/69249. Accessed 05 Sept. 2019

[22] Rendle AB. New philippine plants. J Bot, 1896, 34: 355-362.

[23] Rivett MA. The anatomy of Rhododendron ponticum L. and of Ilex aquifolium L. in reference to specific conductivity. Ann Bot, 1920, 34(4): 525-550.

[24] Shipunov A (2018) Introduction to botany. http://ashipunov.info/shipunov/school/biol_154/. Accessed 25 Aug. 2019

[25] Singh G. Plant systematics, 1999, EnFeild, New Hampshire: Science Publishers Inc.

[26] Volis S. Species-targeted plant conservation: time for conceptual integration. Isr J Plant Sci, 2015

[27] Wang XW, Mao ZJ, Choi K, Park K. Significance of the leaf epidermis fingerprint for taxonomy of genus Rhododendron. J For Res, 2006, 17(3): 171-176.

[28] Zhang C. Dujuanhua (rhododendra), 2003, Beijing: China Building Industry Press.