Monocarpic Mass Flowering of Sasa kurilensis var. jotanii (Bambusoideae) in Mikura-jima, Izu

Abstract

During March through April 1997, Sasa kurilensis (Ruprecht) Makino & Shibata var. jotanii Inoue & Tanimoto (Poaceae: Bambusoideae) exhibited monocarpic mass flowering, beginning partially in the spring of 1996. Several clumps of the plant have been implanted from two distributing areas of Izu Islands; Mt. Oyama, Mikura-jima and Mt. Miharayama, Hachijo-jima into campuses of the Forestry and Forest Products Research Institute, Tsukuba and Utsunomiya University, Utsunomiya, Kanto District, Japan for 13 years. Another clump from Mt. Oyama has been implanted into Tsubota, Miyake-jima, 18 km North of Mikura-jima for more than 20 years. All these implanted clumps flowered at the same spring of 1997. While clumps from Mt. Miharayama did not exhibit flowering both in the native stand and two implanted sites. These facts showed that the mass flowering of S. kurilensis var. jotanii caused by endogenous or genetic factor(s), and not by any environmental factors; the populations in Mt. Oyama and Mt. Miharayama have a different history of establishment. The period of flowering cycle was estimated as 60 years, because an 80-years old villager remembered that last mass flowering had occured on the year at his 20-year-old.