(First upload on December 20 2004. Last on July 20 2018) [ 日本語 | English ]

Polygonum weyrichii Fr. Schmidt ex Maxim.

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

Polygonum L. (タデ)
Urajiro-tade (ウラジロタデ, 裏白蓼), Chinese knotweed or Weyrich's knotweed
Lifeform: perennial forb growing up to 1.5 m
Distribution: Sakhalin - north to central Japan
Habitats: alpine slopes and gravelly places near the sea
Flowering period: July-August on Mount Koma
Flower: hermaphrodite pollinated by insects
Chromosome number: 2n = 20
Aconogonum weyrichii (Fr. Schmidt.) Nakai
Persicaria weyrichii (Fr. Schmidt ex Maxim.) Ronse Decr.
Pleuropteropyrum weyrichii (Fr. Schmidt) H. Gross
Pleuropteropyrum weyrichii (Fr. Schmidt) H. Gross var. alpicola Koidz.
var. alpinum Maxim. (オンタデ), leaf = less hair, green underside (well-developed)
Aco. weyrichii (F. Schmidt) H. Hara var. alpinum (Maxim.) H. Hara
Aco. weyrichii (F. Schmidt) H. Hara ssp. savatieri (Nakai) Tzvelev
Ple. alpinum (Maxim.) Koidz.
Ple. alpinum (Maxim.) Koidz. var. chokaense Koidz.
Ple. weyrichii (F. Schmidt) H. Gross var. alpinum (Maxim.) H. Gross
Pol. savatieri Nakai
Aco. savatieri (Nakai) Tzvelev

⇒ compare to P. sachalinense (オオイタドリ)


Polygonum weyrichii on volcanoes in Hokkaido

[1/2] on the south slope of Mount Koma (flora), southern Hokkaido. [1] on July 9 2018. [2] on July 9 2009. The establishment pattern is regulated by microsites (Titus & Tsuyuzaki 2003). [3-5] near the summit of Mount Yotei (羊蹄山), central Hokkaido, on June 28 2014. [6] var. alpinum, close to the summit of Mount Tokachi, central Hokkaido, on August 6 2001.

Flowers and seeds

PW1 seed2
[1] inflorescences on the south slope of Mount Koma on July 20 2011. [2] on December 19 2004, two days after imbibition. Seeds were collected from Mount Koma on September 8 2004 by Pecapyu Miyoshi (Tsuyuzaki & Miyoshi 2009).