(First upload on June 14 2003. Last on June 6 2016) [ 日本語 | English ]

Rumex obtusifolius L.

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

Rumex L. (スイバ)
Ezo-nogishigishi (エゾノギシギシ, 蝦夷ノ羊蹄), bitter-dock (broad-leaved-dock)
Hirohagishigishi (ヒロハギシギシ, 広葉羊蹄)
Lifeform: deciduous forb
Distribution: native to Europe, now widespread exotic weed (雑草) in Japan
Habitat: disturbed sites, including pastures
R. obtusifolius from the former topsoil on Mount Usu
Gully1 SB2

[1-4] These plants were originated from
seedbank in the former topsoil.

Seeds extracted from the former topsoil

Seed germination method

2 Seedlings emerged from the former topsoil collected in September. The photo was taken on December 24 2008. The experiment was conducted in the greenhosue of Center of Advanced Science and Technology (CAST), HU.

Seed flotation method

3/4 R. obtusifolius seeds, extracted by a centrifuged floation method, in the fall of 2008, 30 years after the 1977-78 eruptions. (Tsuyuzaki & Goto 2001, Tsuyuzaki 2010)


Rumex obtusifolius in Hokkaido


[1] a plant. [2] close-up of inflorescences. [1/2] at Toya Lake Experimental Station, Hokkaido University, on September 8 2009. [3] fruits. at Muroran Marine Experimental Station, HU, on August 23 2010. [4] a rosette in front of GSES, HU, on April 19 2014. [6] along a paved road on a small hill near Sub-Ranger House, Toyotomi Town, norhtern Hokkaido, soon after snow-melt on April 23 2016.