植物地理・分類学会 = The Society for the Study of Phytogeography and Taxonomy
Abstract
The tree Ilex dimorphophylla Koidz.（Aquifoliaceae）is a vulnerable species that is endemic to the summit of Mt. Yuwan on Amamioshima Island, Japan. This plant hows characteristic leaf dimorphism, which increases its horticultural value, and many individuals have been illegally removed from the natural habitat. We examined the umber of shoots, leaf morphology and plant size of the species in the natural habitat. Based on field observation for two years, we found 84 shoots, of which 32（38.1%）had entire mature leaves, whereas 52（61.9%）had only serrate juvenile leaves. Majority of the examined shoots surveyed fell into the smallest size classes : < 100 cm in eight（ca. 45%）and < 25 mm in diameter at the trunk base（ca. 60%）. Leaf dimorphism was clearly demarcated in trees at 130―210 cm in height and 15―27 mm in diameter at the trunk base.アマミヒイラギモチ（Ilex dimorphophylla Koidz.）は奄美大島の湯湾岳山頂付近に発達した風衝林内に生育するモチノキ科の樹木である。本種における樹木サイズと葉の二型性について自生地で調査した。84 シュートの生育を確認し，そのうちの32 シュートが全縁の成熟葉を，残りの52 シュートが鋭い鋸歯のある幼葉のみをもっていた。葉の二型性は樹木高で約130―210 cm，根元直径で15―27mm を境にして分かれていることが明らかになった
