noun
knotweed; smartweed; jointweed
General term for plants of the Polygonaceae family, especially Persicaria and Polygonum species. Often used in compound plant names.
道端にタデの花が咲いていた。
Knotweed flowers were blooming by the roadside.
noun
Specifically Persicaria hydropiper, a species with peppery-tasting leaves. Also called ヤナギタデ.
See also: 柳蓼
タデの葉をかむと辛い。
Chewing water pepper leaves gives a spicy taste.
The origin of たで is uncertain. The kanji 蓼 is a Chinese character used for these plants.