Sadekusa (Persicaria maackiana) is a weed with no particular characteristics. It is one of the so-called "paddy field weeds" that used to be ubiquitous, but due to the recent development of irrigation canals and redevelopment of rice paddies, it is now listed as a semi-endangered species in Kyoto Prefecture's Red Data Book 2015.
The flowers are similar to those of mizosoba (Polygonum thunbergii), but the color is much paler, and the leaves are narrower than those of mizosoba, which are called "cow's forehead. The thorns that grow on the stems are more moderate than those of mamakonosirinugui (Persicaria senticosa) and ishimikawa (Persicaria perfoliata). The name, the flowers, the shape of the leaves, and the thorns give it a slightly elegant look.
これと言って特徴のない雑草です。昔はどこにでもあった、いわゆる水田雑草の一つですが、近年の用水路の整備、圃場整備で、京都府の『京都府レッドデータブック2015』では準絶滅危惧種になっています。
花の形はミゾソバなどに似ていますが、色はぐっと淡く、葉の形はミゾソバが「牛の額」と言われるのに対して、ほそみです。茎に生える棘はママコノシリヌグイなどと比べると、少しおとなしめ。名前、花の姿、葉の形、棘の形態からして、ちょっと上品な趣があります。
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