Leonurus sibiricus L.

Global description
 
Leonurus sibiricus is an annual or biennial herbaceous plant, erect, with straight stem, highly branched, reaching 1 m high. Stem and branches, square section, are covered, on their four sides by a longitudinal groove. The leaves, simple and opposite, are of 2 types: the lower and middle are long-stalked, palmate with lobes divided into narrow segments, the higher ones are short-stalked, linear. The flowers pink to purple in colour, are grouped in globular whorls layered along a terminal inflorescence. The fruit is an ovoid trigonal achene, light brown in colour.
 
Cotyledons
 
The cotyledons have a rounded lamina, with cordate base and emarginate apex.
 
First leaves
 
The first leaves are stalked. The lamina is round with strongly crenate margin. The following are strongly lobed leaves.
 
General habit
 
Annual or biennial herbaceous plant, erect, with straight stem, highly branched, measuring 60 cm to 1 m high.
 
Underground system
 
Tap root.
 
Stem
 
The stem, straight and erect, has lateral ascending branches. Stem and branches have quadrangular section, with obtuse angles. The sides are traversed by a longitudinal groove. They are covered with applied and sparse hairs.
 
Leaf
 
The leaves are simple and opposite, shortly pubescent on 2 sides, the lower and middle, of different shape than the upper. The lower and middle leaves have long petioles (petiole of 2 to 5 cm long), with generally oval blade,  5 to 8 cm long and 3 to 4.5 cm wide, palmate, wedged base, with lobes divided into narrow segments, ending in a point. The upper leaves are undivided, linear, short-stalked, with the lamina 4 to 5 cm long.
 
Inflorescence
 
The flowers, are sessile, grouped into 8 to 25, in compact globular whorls layered on a long inflorescence in the upper part of the plant. The bracts (4-10 mm long), end in a point, prickly, covered with short silky hairs.
 
Flower
 
The calyx consists of a tube (5-9 mm long) marked with 5 ribs, covered with sparse pubescence, extended by five sharp tines, 1.5 to 2 mm long. The corolla, pink to purple in colour, measure 12 to 18 mm long. The tube has an oblique ring of bristles located on the inside, near its base. The upper lip, erect, is oblong convex, pubescent on the outside. The lower lip is trifid, with wide and narrow central lobe and lateral narrow lobes. The 4 stamens are inserted under the upper lip, grouped in pairs of different sizes, the lower pair shorter than the top. The ovary is surmounted by an elongated style terminated by a bilobed stigma.
 
Fruit
 
The fruit is an ellipsoid trigonal achene, 2 to 2.5 mm long, light brown at maturity. Achenes generally 4 in number, remain grouped in the calyx which dries.

Origin

Leonurus sibiricus is native to western Siberia (Mongolia, northwest China).

Worldwide distribution

This species is present in Europe, North, Central and South America and the Caribbean, in the Indian Ocean in Mauritius and Reunion, in Indonesia and in some Pacific islands.

https://www.gbif.org/fr/species/5341392