Alder

trees · nature · nitrogen-fixing

A special partnership. Alder trees partner with tiny bacteria that live in their roots and help turn air into a nutrient called nitrogen that the tree can use, which is why alders grow so well in poor soil where other plants struggle.

Found in cool places. About 35 different alder species live in forests, wetlands, and mountains across the Northern Hemisphere, from North America to Europe to Asia, with a few species even growing in Central America and the Andes mountains.

Both male and female. Alder trees are monoecious, meaning each tree produces both male and female flowers on the same plant, so they don't need another tree to help them make seeds.

Love wet ground. Many alder species thrive in swamps, along riverbanks, and in soggy areas where other trees can't survive, making them important for holding soil in place near water.

Made into useful stuff. People use alder wood for furniture, tools, and even smoking food, while the bark has been used to make dyes and medicines for hundreds of years.