The last Friday in April each year is Arbor Day, and it’s time to mark the 148th anniversary of the first one, started by J. Sterling Morton in 1872 in Nebraska. (“Arbor” is Latin for tree.) Attention to trees will extend into May in Minnesota — it’s Arbor Month.

In celebrating Arbor Day it’s worth revisiting the diversity of these large, amazing plants. By definition a tree is a woody plant that reaches a height of at least 10 feet and has one main trunk with numerous branches and a crown of leaves.

Trees are remarkable natural resources. Much of the world would be bleak without trees. They provide innate beauty and are especially admired in their natural forest settings. Trees can reduce the heat of summer and block the cold of winter. They absorb sound, decrease noise pollution and serve as screens for privacy.

Trees provide us 21st-century people with paper, cardboard and building materials. Leaves of palms and other trees become roofs and clothing. Trees produce edible fruits and nuts. They also produce medicines, such as quinine.

Foremost might be trees’ role in purifying the atmosphere by absorbing carbon dioxide and releasing oxygen. Of course, they also play a vital role in creating habitats for wild animals, providing food, water and shelter.

Jim Gilbert was a naturalist for 50 years.