Persicaria chinensis (L.) Nakai

Global description
 
Persicaria chinensis is an herbaceous plant with many branched stems, prostrate, and only the ends are erect. The stem is shiny smooth, often purple. The leaves are alternately arranged on the stem. They are oval, flat base and has an abruptly narrowed acute apex. At the base of each leaf, develops a membranous sheath tube around the stem. The leaf edge is smooth. The faces are smooth, glabrous, green with a dark spot in the center. The flowers are very small, white to pink in small globular groups, arranged into a loose and branched terminal inflorescence. The fruits are dry, ovoid, black in colour, remaining included in the flower.
 
First leaves
 
The first leaves are simple, alternate. The lamina of the first leaf is very small, almost linear, 3 to 5 mm long. The lamina of the following leaf is oval, wide angled, 10 to 16 mm long and 8 to 12 mm wide, held on a petiole of 2 to 3 mm long.
 
General habit
 
Sarmentous plant, with the main stem mostly prostrate, highly branched, and erect ends. It reaches 1.5 m long.
 
Underground system
 
The root is composed of a main taproot, accompanied by numerous fibrous roots that grow quickly at the stem nodes in contact with the ground.
 
Stem
 
The stem is cylindrical, full, becoming angular and woody at the base. It is generally glabrous and smooth, often purple in color and has small glandular hairs near the nodes.
 
Leaf
 
The leaves are simple, alternate, with petioles 0.5 to 2 cm, often winged on the upper side. At the base of the petiole, there are 2 rounded clasping auricles. . The ocrea is 1 to 2 cm long, obliquely truncated at the top, membranous, glabrous with some small glandular hairs. The lamina is oval to elliptical, 3.5 to 10 cm long and 2.5 to 6 cm wide, acuminate at the top, truncated or wde angled at the base. The margin is entire, sometimes wavy. Both sides are smooth, sometimes with loose hairs on the underside. The venation is marked, consisting of many parallel arched ribs. The leaf blade is green, often with a darker spot in the center.
 
Inflorescence
 
The inflorescence is a loose terminal panicle, bearing at the ends of the branches small glomerules of white or pink flowers, 3 to 8 mm in diameter. The stems, 2 to 3 cm long, are covered with short glandular yellowish hairs.
 
Flower
 
The flowers are held by a short pedicel at the base of which is a foliaceous, oval, sessile bract. The perianth, 3 mm long, is composed of 5 tepals, fused in tube at the base and terminating in lanceolate lobes. 8 stamens shorter than the tepals and an ovary topped by 3 styles.
 
Fruit
 
The fruit is a spherical ovoid achene, 3 to 4 mm long, black. It remains included in the fleshy perianth which becomes bluish black.
 

Origin

Persicaria chinensis is native to India and South East Asia.

Worldwide distribution

This species has been introduced in Hawaii, Jamaica, Pakistan, Reunion, Madagascar and the southern USA.

https://www.gbif.org/fr/species/7987721