PHENOTYPIC AND PHENOLOGICAL PLASTICITY OF AN AQUATIC MACROPHYTE MENYANTHES-TRIFOLIATA L

Phenotypic and phenological properties of Menyanthes trifoliata L. were investigated within and outside of a Phragmites australis (Cav.) Trin. ex. Steud. canopy in a floating peat mat in Mizorogaike Pond, Central Japan. Under the P. australis canopy, M. trifoliata adjusted its phenotypic properties to the conditions of decreased light by increasing leaf blade area, decreasing leaf blade thickness and elongating petioles. The earlier expansion of leaves of M. trifoliata within the P. australis community than outside the community was advantageous in terms of allowing the plant in the mixed community to produce as much dry matter as possible before the foliage of P. australis could overgrow it. Despite the harmful effect of P. australis on M. trifoliata's vegetative growth and reproduction, the latter species can persist in a P. australis community by changing its phenotypic and phenological properties.