Variation in condensed tannin concentration of a temperate grass (Holcus lanatus) in relation to season and reproductive development.

Holcus lanatus, a temperate grass, was found to contain low but measurable concentrations of condensed tannins (CT), according to the vanillin-HCl and the butanol-HCl methods. The variation in CT concentrations between different types of tissue including leaf age and reproductive versus nonreproductive tissue was examined. There was no evidence that floral tissue contained more CT than nonreproductive tissue. A sequential extraction and analysis procedure showed a decreasing proportion of free-unbound CT and greater preponderance of protein-bound and fiber-bound CT with increasing leaf age and in dead matter. Samples collected from an agricultural pasture on two sampling dates, January 24 and March 5, 1993, showed short-term temporal variation in free-unbound CT.