樹木起源の珪酸体について(20周年記念号)

抄録

Morphological analyses of opal phytoliths in soils derived from grasses and trees were very useful for the reconstruction of vegetative history. The deposition site, degree of silicification and the morphological features of phytoliths in various tree leaves were examined under the polarization microscope and scanning electron microscope, and the source of phytoliths in soils were assumed from observation of morphological features of phytoliths in tree leaves. The results were summarized as follows: 1) The deposition site of silicification in tree leaves were most prevalent in vascular elements, epidermal cells, epidermal hairs and hair bases. The trees which contained phytoliths apparently were Magnoliaceae, Moraceae, Ulmuaceae, Faguaceae and Palmae. The degree of silicification in broad-leaved trees belonging to the same family varied with genus, species and sampling time, but phytoliths in evergreen trees were generally clearer in shapes than those of deciduous trees. 2) The amounts of silicic acid and phytoliths in tree leaves were lower than those of Gramineae. Among trees, Magnoliaceae, Moraceae, Ulmuaceae, Faguaceae, and Palmae were comparatively higher in its amounts. 3) The phytoliths were markedly different in shapes among broad-leaved trees, conifers and palms. Conifers generally contained simple cubic and irregularly shaped polyhedron phytoliths, while broad-leaved trees contained jisaw-puzzle shaped, hexagnoid or pentagnoid plate shaped, twisted and branched elongate, spindle shaped, blade shaped, irregular sphere or oval shaped and hollow-sockted hair cell phytoliths. 4) Some of phytoliths isolated from present and buried volcanic ash soils in Kyushu, red yellow podzolic soils in Okinawa Honto and red soils in Bonin Island (Chichigima) were derived from trees. Most of phytoliths of tree origins, found first in volcanic ash soils from Tanegashima and Yakushima, were found to be quite similar to those of vascular cells in Distylium racemosum Sieb. et Zucc. leaves.