Different plants form symbiotic relationships with specific microorganisms that act as biofertilizers, enhancing nutrient uptake, most notably nitrogen fixation. Legumes like soybean associate with Rhizobium. The aquatic fern Azolla hosts the cyanobacterium Anabaena azollae. Many trees, including pine, form mutualistic associations with fungi known as Mycorrhizae. Cereals like maize can associate with bacteria like Azospirillum in their root zone.