A plant genus of the family ASTERACEAE. Members contain pectolinarin (a flavonoid glycoside).
The only living genus of the order Equisetales, class Equisetopsida (Sphenopsida), division Equisetophyta (Sphenophyta); distantly related to ferns. It grows in moist places. The hollow, jointed, ridged stems contain SILICATES.
A group of 4-keto-FLAVONOIDS.