Erigeron annuus

Fine beam ( Erigeron annuus )

The fine-beam ( Erigeron annuus ) also called White fleabane or Yearling fleabane, belongs to the sunflower family ( Asteraceae). It is in this kind of a neophyte from North America, which has run wild as former ornamental plant since the 18th century.

Description

The fine beam grows as an annual or biennial herbaceous plant with erect stems, reaching heights of growth between 50 and 100 cm. With its up to 1 m deep ground penetrating root He is a pioneer plant. The leaves are simple, the leaf edges sawn until almost smooth.

The numerous basket- shaped part inflorescences are arranged in a corymb, the terminal flower heads is here dominated by the lateral. The bracts are green, almost the same length and slightly hairy. The ray floret ( = rays flower) is white to pale purple and 4-8 ( to 10) mm long and 0.6 to 1 mm wide. The yellow tubular flowers are 2 to 2.8 mm long. The pappus of tubular flowers is very short and uniseriate. Bloom time is from June to October.

Special feature: This species reproduces asexually largely, ie Seeds are formed without fertilization ( apomixis ).

Occurrence

The fine beam preferred riparian forests, wet meadows, ruderal. In Austria it is scattered to common in all states. In Germany penetration rates are rising roughly from the south to the north. In the Black Forest, he is often found in some northern German territories he rarely occurs. The fine beam is also common in Switzerland.

System

In Austria several subspecies exist, their dissemination is still insufficiently researched:

• Vielblättriger fine beam ( Erigeron annuus (L. ) Pers. Subsp. Annuus )
• Nordic fine-beam ( Erigeron annuus subsp. Septentrionalis ( Fernald & Wiegand ) Wagenitz )
• Branched fine jet or harrow Hairy fine beam ( Erigeron annuus subsp. Strigosus ( Willdenow ) Wagenitz )