4.2 Weed Biology – Reproduction via Seeds

Let’s start off this chapter with a quick review of some biological principles, as they apply to field crop systems. There are two types of weeds which reproduce ONLY by seed: 1) annual weeds and 2) simple perennials. They do not have the ability to vegetatively propagate.

In terms of seed production from the weed’s perspective, their goal is to spread their population over both space and time. What we mean by “space” is geographic space, whether that is simply a few feet away from where the mother plant is or in another field or county, depending on their dispersal mechanism. By “time”, what we mean is some of the population’s seeds will remain dormant, to germinate in later years.

In contrast, this is quite different from the seed production goals we have for our crops. We do not want the seed spreading to a neighbor’s field and when we plant the crop in the spring, we want 100% germination rates. Our crop plants have been developed by plant breeders to have these different types of seed traits.