Screw (Bostryx) is a certain form of inflorescence . Below the terminal flower of the main axis there is only a minor axis closed off by a flower, which continues to drive a minor axis with a flower either to the right or to the left.
One variant is the double screw . This has the first branch on both sides of the main axis and others like a simple screw.
St. John's wort ( Hypericum perforatum )
- Strasburger, E. et al .: Textbook of botany for universities . 15th edition, Jena Verlag by Gustav Fischer 1921, pp. 114, 488
- Strasburger, E. et al .: Textbook of botany for universities . 35th edition, Spektrum Akademischer Verlag 2002, p. 168