The Arnold Arboretum of Harvard University

The Arboretum for Educators

Resources for Teachers, Students, and Families
 
June 2026
June is the last month featuring one native tree species per month, highlighting recognizable features and sharing interesting facts. This will be followed by Outdoor Journaling suggestions and related Science Labs. Embark on a yearlong tree investigation and outdoor journaling program: can you “collect” all 10 trees by June?  Be sure to read the previous newsletters.
If you have used any of the journal or science activities from previous issues, please take a few minutes to share some feedback using this form.

Tulip Tree: Carbon Thief

Traditionally, trees are grouped as having hardwood or softwood. In general, hardwood comes from broad-leaved, deciduous, flowering trees, like oak or maple. The wood is generally high density, durable and better suited for furniture and flooring, because these trees grow slowly. Softwood comes from cone-bearing, needle-leaved trees, like pine or cedar. This wood is excellent for construction and framing as it is lighter, less dense and easier to cut; softwood trees grow more rapidly. The wood of the tulip tree (Liriodendron tuipifera) breaks this mold! It is fast-growing (up to 36 inches per year when young and under optimum conditions) and has strong wood. It wasn’t until 2024 that scientists were able to explain this combination and coined the new term “mid-wood” expressly for the tulip tree wood. What they discovered was that the wood structure of the tulip tree is unique, and by tracing its evolutionary history, they hypothesized that tulip tree mid-wood adapted to sequester carbon more efficiently than other plants. This finding makes the tulip tree another important native tree to plant when fighting global change due to a warming climate.
Upward view from the base of a tall tree with rough, textured bark, its long branches spreading out into a dense canopy of green leaves against a bright sky.
Tulip Tree (Liriodendron tulipifera) is a member of the Magnolia family and only North American species of this genus; the other being Liriodendron chinense, the species native to Asia.

It is the tallest flowering tree in North America, and can grow to more than 160ft, though it more commonly reaches heights between 80 and 120 feet tall. It is an outstanding shade tree and has large and showy tulip shaped flowers that excel at producing nectar.
Close-up of a pale yellow and orange flower, showing a central cone surrounded by many slender, radiating petals and stamens, with green leaves softly blurred in the background.
In terms of nectar production, a single flower can secrete 1/3 tsp of nectar, a 20-year-old tree is estimated to generate enough nectar to produce 4 lbs. of honey, and larger, more mature trees can generate up to 9 lbs! Because of the high volume, nectar can pool and drip from the flowers. It is easy to spot shiny, sticky, sweet nectar pooling on the petals and dripping onto leaves.

The nectar’s sugar content of an individual flower increases over time, from 17% sugar when the blossom opens to over 35% sugar content within a few days. It is produced in a yellow-orange ring inside the cup-like petals and is exuded through modified, sunken stomata known as nectarostomata.

Pollinators include native and honey bees, butterflies and hummingbirds.
Fallen pale yellow petal with an orange base lying among green leaves.
Outdoor Journal Activities
  1. Come to the Arboretum to meet our tulip trees! Find a branch and notice all the different leaf sizes. Can you visually sequence them from the smallest leaf to the largest one on the same branch? Why do you think the leaves are all different sizes? How is that different from other trees?
  2. Find some leaves from the tulip tree on the ground and use them to make leaf rubbings. Notice the vein patterns and leaf shape. Try to make a bark rubbing directly from the trunk!
  3. Look carefully at a flower and all its parts. Look for the shiny nectar drips on the petals. Touch it and smell it! Make a detailed drawing of what you observe.
  4. Read aloud The Great Pollinator Count by Susan E. Richmond, print out the teacher resources and take students outside to observe and count pollinators in their schoolyard.
Science Labs
  1. Project Learning Tree has a comprehensive unit called Counting Carbon. Once students learn how to calculate carbon sequestration, they can then engage in evidence-based discussions around sustainability, reforestation, and the potential role of tulip trees as efficient carbon sinks.
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