Effects of plant density on chasmogamy and cleistogamy in Lespedeza cuneata (Fabaceae)

Abstract

Lespedeza cuneata (commonly "sericea") is an invasive, exotic, perennial legume. Sericea can produce two types of flowers on the same plant: self-pollinating cleistogamous (CL) and open-pollinating chasmogamous (CH). The purpose of this study was to determine if the ratio of CH to CL flowers is affected by plant density. Flowering in low-, medium-, and high• density stands of sericea in a Greenwood County, Kansas, pasture was monitored over the 10-week flowering period, August to October, 1999. Two-way analysis of variance of these data indicated no difference among density treatments in CL flowering (P = 0.168). Significant variation was found among density treatments in CH flowering (P = 0.041). Cleistogamous and CH flowering varied significantly among weeks (P < 0.001). Pastures in which sericea density is reduced by weed control treatments that fail to eliminate all sericea plants will likely produce a higher proportion of CH flowers in the remaining plants than found prior to the control treatment. Heterosis in these remaining plants could produce a more vigorous infestation than that prior to weed control treatment.