Épiphytes, parasites et carnivores

Unlike most animals, plants cannot move from one place to another in search of food. To survive, plants must gather light and nutrients by growing and moving in place. Plants obtain food through two different means: autotrophy and heterotrophy.

Autotrophic plants synthesize their own food through photosynthesis. Light energy—captured by chloroplasts—drives the creation of sugars that nourish the plant.

Heterotrophs, however, rely on another organism for nourishment. Heterotrophic plants, such as dodder vine, often lack chloroplasts and cannot make their own food.

Dodder vine is a leafless, climbing, plant parasite. It absorbs nutrients from its plant host, causing the host harm or sometimes death. 

Modified root projections called haustoria invade the host plant’s vascular tissues to divert water and nutrients for the parasite’s growth. Dodder can also spread to neighboring plant hosts, creating a nutritional supply system for itself.

The staghorn fern has chloroplasts and is, hence, an autotroph. Staghorn fern illustrates a different kind of nutritional adaptation—it is an epiphyte or “air plant,” that grows on other plants, such as trees, for physical support. 

Epiphytes benefit from this relationship because the host plant often secures them a higher position in the forest canopy that provides more light for photosynthesis, while the host plant does not suffer damage.

Epiphytes have specialized roots that may anchor them to the host. They also take up water and nutrients from the air or organic debris that accumulates near their anchoring point. Additionally, the leaves of epiphytes absorb moisture and nutrients from the air and rain. 

Pitcher plants are mixotrophic—both autotrophic and heterotrophic—carnivores that live in sunny, acidic, nutrient-poor bogs. Since bog soil is nitrogen-deficient, pitcher plants rely on carnivory to supplement their nutrition. The pitcher plant’s specialized leaves form funnels, which trap and drown prey, such as insects and other small animals, in its digestive fluid.

Despite being stationary, plants evolved remarkable adaptations to reduce the effects of environmental stressors, such as low light or poor nutrient availability. Plants like the staghorn fern, pitcher plant, and dodder vine access valuable resources by utilizing other organisms in their environment.