Popular black cottonwood

Black cottonwood: Courtesy Oak Point Nursery
Black cottonwood: Courtesy Oak Point Nursery

Ever heard of Populus trichocarpa? It sure is shaking up what researchers understand about plant biology and evolution. That’s right, Populus trichocarpa is a tree, more specifically a black cottonwood.

The black cottonwood is the first tree to have its full DNA code sequenced. Reports state the poplar tree has far less DNA in its cells than humans or other mammals, but twice the number of genes. The poplar has 485 million basepairs! Basepairs are the letters orchestrating a genetic code (A=adenine, T=thymine, C=cytosine, G=guanine). Researchers have found more than 45,000 possible genes (units of hereditary information). To put this number in perspective, humans and other mammals have a little over 20-25,000 genes.

Why is this cool?

Besides figuring out specific questions about botany, having the full DNA sequence of the black cottonwood will also have industrial implications.

The research team discovered 93 genes of the poplar where involved in making cellulose. Cellulose is an organic material found in large quantities on Earth. Cellulose is the primary structural component of green plants. It can be broken down into sugar, fermented into alcohol and distilled to produce fuel-quality ethanol.

Dr. Gerald Tuskan, the lead author of the report in Science, stated, “Biofuels are not only attractive for their potential to cut reliance on oil imports but also their reduced environmental impact.”

Populus trichocarpa identification:

Leaf structure: Alternate, simple, deciduous, ovate-laneolate to deltoid, dark green and silvery white underneath, wavy margins.

Fruit: Releases cottony-tufted seeds
Bark: When young, it is smooth and yellowish tan to gray; later on it turns gray to gray-brown and has deep furrows and flattened ridges.

Form: Tallest broad-leaved tree in the West. Able to grow up to 200 feet tall and 6 feet in diameter.

Found: Flood plains and along river and stream banks. Prefers moist/wet sites.

Keep your eyes open for a black cottonwood tree near you!

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