Which category of plants lives on and takes nutrients from host plants?

Parasitic seed plants represent a unique category of plants that obtain some or all of their nutritional requirements from a host plant. This adaptation allows them to thrive in environments where resources may be limited. Unlike other types of plants that primarily rely on photosynthesis to produce their own food, parasitic seed plants connect to the vascular system of their host through specialized structures called haustoria. This connection provides them with water and essential nutrients, enabling their growth and survival.

Emergent plants, while they thrive in wetland conditions and can be partially submerged, do not depend on host plants for their nutrition. Instead, they primarily perform photosynthesis like most other plants. Vines are known for their climbing growth habit, often using other structures for support, but they also do not obtain nutrients from a host plant in the way parasitic plants do. Ferns, being non-flowering plants that reproduce via spores, also do not have a parasitic lifestyle; they are autotrophic, creating their sustenance through photosynthesis.

Thus, the correct identification of parasitic seed plants accurately reflects their distinct method of nutrient acquisition, contrasting with the other categories mentioned.