Zone 9 is one of the most diverse regions in the world. It includes some of the driest areas, most temperate zones, and even a few tropical islands. The area is characterized by its high elevation (over 13,000 feet) and cold winters. It’s also home to many species of plants that are not native to other parts of North America or Europe.
Evergreens are the most common type of tree found in zones 8 through 10. They grow from 4 to over 20 feet tall and have wide spreading branches. Most evergreen trees need little care, but they do require regular pruning to keep them healthy and looking their best.
Evergreens generally prefer moist soil, so make sure your garden is well drained before planting any evergreen trees!
Evergreens are often used for shade during hot summer days. They’re also great for creating a focal point in a landscape. They make excellent houseplants because they don’t require much water and will tolerate almost any climate.
Evergreens are very drought tolerant, which makes them ideal for gardens where there may occasionally be periods of dry weather.
The most common types of evergreens are the arborvitae, hemlock, juniper, cypress, pine, and spruce trees. The Arborvitae is a popular evergreen in the northeastern US. Arborvitae grow quickly and tolerate shade, so they make great groundcovers in areas that receive full sun.
They generally only grow to about 4 feet tall at maturity. The Arborvitae makes a great choice for people who want an evergreen hedge, but don’t have enough space for a larger tree.
The Hemlock is also a fast growing evergreen that grows up to 50 feet at maturity. The hemlock is well known as the tree that killed Socrates. Poison hemlock gets its name from the fact that it closely resembles wild mushrooms, both in appearance and in the symptoms it causes if ingested.
The hemlock tree was used to make poison gas during World War II. The poison gas, known as lewisite, causes a painful death by destroying a person’s lungs.
One of the most popular evergreens is the juniper. It grows small blue berries that are edible. Some varieties, like the Juniper Procumbens Nana stay under 2 feet in height.
Other varieties, like the Juniperus Virginiana stay between 3 and 5 feet tall at maturity. That makes the juniper a great choice for people who live in small homes or flats.
The Cypress tree gets its name from the fact that ancient Greeks and Romans used to burn its resin to ward off insects. That’s what gives it an evergreen smell, like the one you smell at Christmas when you open a new toy that has been stored in a plastic bag. In many parts of the US, people use it as a Christmas tree.
The Pines are some of the most common evergreens in North America. They get their name from their pine-like foliage. There are several varieties of pine, including the Virginia Pine, Loblolly Pine, Longleaf Pine, and Shortleaf Pine.
The loblolly is one of the tallest pines in North America and can grow to over 100 feet at maturity. It prefers wet soil and can tolerate partial shade. The longleaf grows in the southeast and can grow to almost 60 feet at maturity. It is well adapted to fires and without fires it will begin to grow too densely, which makes it more susceptible to disease.
The Spruce is not actually a pine, but gets its name from the spiky look of its needles. It grows well in the shade and can grow up to 90 feet at maturity. The Colorado Blue Spruce is one of the most popular varieties of Spruce.
The yew is a small, evergreen tree that is actually poisonous. It has reddish bark and grows up to 40 feet at maturity. The Latin name for the Yew is taxus, which gives us the word toxic.
The yew is also a popular wood for making bows.
This concludes this edition of BTB Education. Tune in next time, when we discuss more fascinating topics in tree science!
Sources & references used in this article:
Evergreen trees do not maximize instantaneous photosynthesis by CR Warren, MA Adams – Trends in plant science, 2004 – Elsevier
Different photosynthesis-nitrogen relations in deciduous hardwood and evergreen coniferous tree species by PB Reich, MB Walters, BD Kloeppel, DS Ellsworth – Oecologia, 1995 – Springer
Why do evergreen trees dominate the Australian seasonal tropics? by D Bowman, LD Prior – Australian Journal of Botany, 2005 – CSIRO