Common Meadow-rue

Thalictrum flavum has fibrous roots, and wedge-shaped, dark green leaves, with a paler green underneath; they are divided into multiple sections. It blooms between June and August. The flowers are composed of short sepals and longer, erect stamens. The sepals are actually white, but the multiple erect, yellow stamens, give the flower a yellow appearance. Later, three fruits are formed from each flower head.

Phytochemistry. The plant contains an enzyme called pavine N-methyltransferase, which modifies a variety of benzylisoquinoline alkaloids including the eponymous alkaloid pavine. Benzylisoquinoline alkaloids like pavine often have a variety of pharmacological actions, and as a result some have medical uses such as analgesic or anticancer effects while others have significant toxicity. T. flavum also contains another benzylisoquinoline alkaloid, thalidezine, which is also present in other Thalictrum species.

It is very widespread, and is native to temperate regions of Asia, Northern Africa and Europe.

Range. It is found in Northern Africa within Algeria. In Europe, it is found in (Eastern Europe) Belarus, Estonia, Latvia, Lithuania, Ukraine, (Middle Europe), Austria; Czech Republic, Germany, Hungary, Poland, Slovakia, Switzerland, (northern Europe) Denmark, Finland, Ireland, Norway, Sweden, United Kingdom, (southeastern Europe) Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Italy, Montenegro, North Macedonia, Romania, Serbia, (southwestern Europe) France and Spain. In Asia, it is found in the Caucasus, (within Azerbaijan and Georgia) Russian Federation, (within Amur and Primorye), China, (Xinjiang,) Kazakhstan, Siberia and Turkey.

It has naturalised in the UK, and found in southern and western England, as well as in Scotland and Ireland.

Habitat. It is found generally in grasslands, marshy fields, fens and riverbanks.

It is pollinated mainly by flies and bees, with wind dispersal of the seeds. The larva of the Perizoma sagittata (Marsh Carpet moth) are found on the plant, eating the seeds and the flowers.

It has been used in folk medicine in the UK, the foliage has been used a purgative.