What are parasites in the context of plant biology?

In the context of plant biology, parasites are defined as organisms that live on or in another organism (the host) and obtain their nutrients at the host's expense. This relationship is characterized by the fact that the parasite derives sustenance from the host, often leading to some harm or detriment to the host organism. For instance, certain parasitic plants, like dodder or broomrape, attach themselves to other plants and extract water and nutrients, severely affecting their host's health and growth.

The other options do not accurately describe parasites: the first option refers to flowering plants, which highlights reproductive characteristics rather than feeding behavior. The second option describes autotrophic organisms, such as green plants, that create their own food through photosynthesis, which does not align with the definition of parasitism. The fourth option pertains to plants that may exhibit a lack of roots, but again, this does not relate to the concept of feeding off another organism.