Phytoliths of sago palms (Metroxylon sagu Rottb.) in three soil profiles (94 cm depth) that were collected in Pangasugan (coastal area, western part of Leyte), Julita (slightly interior lowland area, eastern part of Leyte), and Dulag (coastal area, eastern part of Leyte) in the Philippines in 2019 were used as indicators for reconstructing plant communities and evaluating sago palm cultivation. All three soils were classified as Eutropepts, which are dominant in colored minerals such as augite, hypersthene, hornblende, and iron compounds. Arecaceae phytoliths were categorized into five groups; spheroid echinate (including M. sagu phytoliths), globular echinate, hat-shaped to conical, ellipsoid echinate, and others. Spheroid echinate phytoliths in soils at the three sites accounted for 6-76 % of the whole, and their content was especially high at depths of 0-16.5 cm in the Pangasugan profile (57 %), 16.5-32 cm in the Julita profile (58 %), and 32-63 cm in the Dulag profile (76%). In the Dulag soil profile, the frequency percentage of spheroid echinate phytoliths was high throughout the layers, except at depths of 63-78.5 cm and 78.5-94 cm. The dominant sizes of spheroid echinate phytoliths were 5-10 μm (47.0%) for Pangasugan, 5-10 μm (24.7%) and 10-15 μm (30.9%) for Julita, and <15 μm (25.4-27.0%) for Dulag. Based on the gathering of the small spheroid echinate phytoliths in the surface layer in the Pangasugan soil profile and that of the large spheroid echinate phytoliths in the subsurface layers in the Julita and Dulag soil profiles, it was concluded that sago palm cultivation started in recent years in western Leyte, whereas it has continued for a long period in eastern Leyte.

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 The disulcate pollen grains of Metroxylon sagu extracted from different soil layers up to 1 m were investigated to elucidate their growth and distribution history in the three sago growing sites of Pangasugan (western part of Leyte, facing the Camotes Sea) and Julita and Dulag (eastern part of Leyte, facing the Pacific Ocean), Leyte, Philippines. The M. sagu pollen grains were found to be medium-sized, elliptical, and disulcate under a transmitting-light microscope at a magnification x400. In Pangasugan, M. sagu pollen grains had a frequency percentage of seven only in the surface layer; they were not found in the subsurface layers. Meanwhile, the pollen grains of M. sagu at Julita and Dulag were present in the surface and subsurface soil layers with high frequency percentages. These results suggested that the long cultivation of M. sagu had been developed in wide alluvial lowlands of the eastern part of Leyte Island especially. It is concluded that the people who migrated to Leyte, Philippines, kept M. sagu and utilized the biomass of M. sagu, including starch.

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 We investigated differences in the growth characteristics and starch productivity of tall sugar palms with high sap productivity according to plant age (estimated: 3–25 years) and growth stage (early trunk elongation to dying stage) in Sandabilik (SB) Village, Tana Toraja, South Sulawesi, and in Taratara (Ta) Village, Tomohon, North Sulawesi, Indonesia. The number of years until the emergence of the first female inflorescence after the seedling stage was approximately 10–12 years in SB Village and 8–10 years in Ta Village, and that until the end of sap collection was approximately 20 and 15 years, respectively. In both villages, trunk elongation and leafing occurred until the emergence stage of the first female inflorescence, and the highest trunk weight was estimated to be 1500–2000 kg during the period from the emergence stage of female inflorescences to the early emergence stage of male inflorescences; the pith starch percentage also reached the highest values, 30–40%, and the starch content was estimated to be 100–250 kg during this period. After that, the pith starch percentage and content tended to decrease in the dying stage. However, it was suggested that the starch content might increase with the passage of time after the end of sap collection in plants that have maintained large leaf areas and high leaf chlorophyll content even in the dying stage.

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