Vegetation living in agricultural channels (drainage ditches or irrigation channels) supports ecosystem functions such as water flow regulation; retention of sediments, agricultural pollutants and plant propagules; and bank strengthening. The review focuses on plant community functional parameters (aggregations of plant functional traits) and community properties that need to be considered to study the dynamics of these ecosystem functions, to support further modeling work on the functioning of these semiaquatic ecosystems. It also provides an up-to-date overview of the effects of channel management practices on vegetation, because these practices are a potential lever with which to drive plant community functional parameters and properties and, in turn, ecosystem functions. The review points out that the mean height, density, and flexibility of the plant cover, sometimes integrated in the “blockage factor”, mainly influence the average components of the water flow associated with the functions of water regulation, and retention of sediments and non-floating propagules. The density of plants, or area of the plant cover at the water surface, are generally used to explain floating propagule retention. The biomasses of living and dead vegetation are the properties used to assess the retention of agricultural pollutants. Root density and root length density, as well as tensile strength of the root system, are parameters generally associated with bank strengthening. Regarding the effects of channel management practices, this work highlights that research generally has focused on the resulting plant richness and diversity, but has not provided much information on associated plant community functional parameters and properties.