BIOTA Philippines Conference System, 52nd BIOTA Annual National Convention and Scientific Sessions

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Leaf Anatomy of Selected Philippine Hoya R. Br. Species
Annalee Soligam Hadsall, Antonio L Rayos

Last modified: 2017-03-11


The genus Hoya R. Br. of Family Apocynaceae, Subfamily Asclepiadoideae includes over 300 species of woody angiosperms often growing as epiphytes. Co’s Digital Flora of the Philippines lists 121 species, most of which are  endemic to the archipelago. Leaf anatomy of four species, namely, H. halconensis Schltr. ex Kloppenburg,  H. lacunosa Blume,  H. madulidii Kloppenburg, and H. meliflua (Blanco) Merr. revealed variations in terms of epiphytic adaptations. Upper epidermis has two layers in H. lacunosa and three in H. meliflua. Having multiple epidermis enables  these species to retain water in their leaves. As epiphytes, they need mechanisms for water conservation since they are faced with the problem of  water deficiency.  The size and abundance of air spaces in the spongy mesophyll were also found to be varying among the four species. InH. halconensis and  H. madulidii, air spaces are relatively large and profuse. In H. meliflua, air spaces are relatively small but abundant. However, in H. lacunosa, air spaces are relatively small and scarce.  This initial study in Hoya leaf anatomy will contribute towards understanding evolution of epiphytes.

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