Neighborhood interference among velvet leaf, Abutilon theophrasti and pigweed, Amaranthus retroflexus.

Although survivorship was density-independent for both species, individual fecundities were affected by the local population density of velvet leaf and pigweed near each plant. For both species hyperbolic functions provided better fits than either linear or log-linear functions. Aspects of the functional forms of the relations between fecundity and local densities are explained in terms of morphological attributes of each species. -from Authors