Are there symbiotic relationships involving plants?
Written by
Benjamin Miller
Reviewed by
Prof. Charles Hartman, Ph.D.Plants engage in astonishing symbiotic associations with a host of partners, including bacteria, fungi, and other plants. These relationships reflect a broad spectrum, from mutualisms based on nutrient sharing to commensalisms that are harmless. Orchids live on trees to access more sunlight, but they do not compete with other plants for resources. Legumes contain nitrogen-fixing bacteria, which naturally fertilize the soil.
Mycorrhizal Fungi Networks
- Over 80% of land plants form underground fungal partnerships
- Fungi extend root systems absorbing water and phosphorus
- Plants provide sugars produced through photosynthesis
- This mutualism creates nutrient exchange networks
Nitrogen-Fixing Bacteria
- Legumes like beans and peas host rhizobia bacteria in root nodules
- Bacteria convert atmospheric nitrogen into plant-usable ammonia
- Plants provide carbohydrates and protected growth environment
- This natural fertilization improves soil quality
Epiphytic Commensalism
- Orchids and bromeliads grow on tree branches without harming hosts
- Plants access better sunlight and rainwater collection positions
- Host trees experience no resource loss or structural damage
- This relationship demonstrates one-sided benefit
Mycorrhizal networks represent elaborate underground mutualism. Fungi create vast webs that connect several plants and transfer nutrients between species. Trees share resources with seedlings through the fungal passages. This underground communication system enables the entire forest to cope with environmental stress conditions, such as drought.
The symbiosis of legumes and the rhizobia has revolutionized agriculture through natural soil fertilization. Farmers rotate their crops with legumes to increase the nitrogen content in the soil without the need for added fertilizers. I have measured yields that are 50% higher in bean fields with living, active bacterial nitrogen nodules, resulting in a greater reduction in fertilizer runoff for sustainable agricultural practices and cleaner waterways.
Epiphytic plants have specialized adaptations for living in a commensal growth form. Orchids grow aerial roots that can absorb moisture from the humid air. Bromeliads create tanks for collecting water in the leaf bases. This adaptation gives them the chance to grow without direct contact with the soil, but they receive their mechanical support from above in the trees.
Parasitic species, such as mistletoe, are harmful parasites that burrow their way into the vascular system of their host, robbing it of water and nutrients. When these parasites infest the host severely, they weaken it and leave it prone to disease. A key aspect of forest management is controlling these parasites, thereby maintaining the ecosystem's health.
Read the full article: 10 Symbiotic Relationships Examples in Nature
