Bird knotweed

Bird's knotweed, also known as Polygonum aviculare, is a plant species within the knotweed family (Polygonaceae). On rubble areas, fields and paths, especially in Central Europe, the hardy shoots typically grow horizontally creeping up to a length of 50 cm with narrow elliptical leaves and white to pink flowers. Flowering time: May to November. The small, dark brown nut fruits, up to three mm in size, each contain one seed.

The dried aerial parts of the plant are used phytotherapeutically: leaves, stems and flowers (bird's knotweed - Polygoni avicularis herba).

The bird knotweed is an annual plant whose roots can reach a depth of up to 80 cm; the stems growing upright have a length of up to 60 cm. The elliptically shaped leaves are grass to blue-green in colour. Polygonum aviculare flowers from May to October.
During this time the flowers sit singly or in small groups of up to six flowers together. The flowers are greenish in colour with a white, pink or reddish edge. The smooth nut fruits are 2 to 3 mm in size.

Polygonum aviculare is the parent plant of Polygoni avicularis herba, the herb of the plant, which is collected and dried with the roots during the flowering period.

1. https://arzneipflanzenlexikon.info/vogelknoeterich.php

2. Blaschek W (2015) Wichtl tea drugs and phytopharmaceuticals. A handbook for practitioners. Wissenschaftliche Verlagsgesellschaft Munich. S 515-516