Systematic Study of the Genus Orchidantha (Lowiaceae) in Malaysia

Nur Syauqina Syasya, Mohd Yusoff (2019) Systematic Study of the Genus Orchidantha (Lowiaceae) in Malaysia. Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

Lowiaceae is the poorest known family in Zingiberales Order due to its small number of species and always neglected by botanists. This family contains the only sole genus of Orchidantha with a total of twenty-five updated species. In Malaysia, there are sixteen species recorded including four new species discovered during this study. This study compares morphological, anatomical and palynological characteristic of Orchidantha species in Malaysia. Fresh samples and herbarium specimens were mostly used to examine the morphological characteristic. While, only fresh samples were used for anatomical and palynology study. The location of every species collected was mapped and recorded. Orchidantha was observed grows near the stream in a damp place. They are hyper endemic, lowland plants that dominate forest floor. Flower plays an important role in distinguishes the species since the plant itself showed no different in morphological characteristic among the species. Critical flower parts that used for species identification are labellum, stigma and petal. Identification key to Orchidantha species in Malaysia normally based on detail morphological examined. Cross section of petiole and midrib were used to distinguish between the species. It was found that there were different shapes of petiole adaxial outline in every species. Meanwhile, from the midrib cross section, the leaves show different degree of attachment among the species. Orchidantha possess a vascular system that arranges in a shape of an arc. There are up to five types of vascular systems found in petiole while either two or three vascular systems found in midrib. Air chamber was observed to lie alternating the vascular systems in both petiole and midrib. Micromorphology study of epidermal cell shows differences in the anticlinal wall and cell shape of upper and lower epidermal layer of the same species and between the species. Stomata were abundantly found on the lower epidermis. Most of the stomata are sunken with various types of stomata; anomocytic, tetracytic, branchytetracytic and paratetracytic. Pollen of Orchidantha species is all psilate with sphaeroidal shape. The differences can be showed only by the size of pollen; magna, gigantha and premagna. Therefore, the pollen could not be used in identifying species. This study had covered the morphological, anatomical and palynological character of Orchidantha in Malaysia. Nevertheless, further research should be done since there are lack of knowledge and information especially on molecular, ecological and embryology of Orchidantha. Keywords: Hyper endemic, Lowiaceae, Malaysia, Orchidantha, Zingiberales Order.

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