Everything You Want to Know About Thuja

Part of gardening is getting to know the background to your plants, finding out more than just their vital statistics. So rather than talk about what a great hedging plant Thuja Green Giant is, or how fast it grows, in this blog I am going to fill in some background to this tree, by telling the interesting story of Thuja as a group, and some things about the two parents of this tree.

Arborvitae or Cedar?

One thing that often confuses gardeners is the difference between the scientific names and the common names of plants. In the group scientists call ‘Thuja’, there are some trees that are commonly called ‘Cedar’, and others called ‘Arborvitae’. For example, Western Redcedar is, to a botanist or horticulturist, Thuja plicata. Its close relative, growing in eastern North America, instead of the west, is Thuja occidentalis. ‘Occidentalis’ by the way, means ‘western’, which seems odd, since this plant grows in eastern North America. However, the whole continent was west of Europe, where the first explorers came from, so to them it was certainly in the west.

Now where did this strange name Arborvitae come from? The story is an interesting one, and goes back to the arrival in North America of the French. In 1534, Jacques Cartier made his first voyage to North America, sailing round what is today Newfoundland and into the Gulf of the St. Lawrence river. He returned in 1536, but this time his crew was struck by a deadly disease – scurvy. This was a curse of long ocean voyages at that time, and the fact that it could be cured by eating citrus fruit was known to the Spanish as early as 1497, but they kept the secret, not wanting to help their enemies. Cartier had a crew of 110 men. 25 died from scurvy, and Cartier himself began to show symptoms.

In the winter of 1536, his boat was trapped in the hard-frozen ice of the St. Lawrence river, and he was on cautious but not hostile terms with the local Iroquois Indians. When he told them of the sickness he and his crew were suffering, they showed him how to make a drink called ‘aneda’ from a local plant. Cartier and his sailors used the bark from an entire tree in one week, consuming the drink in large quantities. Within a few days their symptoms disappeared, and they were well again. The cure was nothing short of miraculous, and allowed the remaining 85 men to survive the winter and return to France. Considering the life that had been restored to them, Cartier called this tree ‘Arbor Vitae’, which is Latin for Tree of Life. While the plant was later described as Thuja occidentalis, the arborvitae name stuck among ordinary folks, and has been attached to other Thuja trees ever since.

The origin of the name ‘cedar’ for these trees is not quite as exciting, but still interesting. It is a name that dates back at least to the 13th century, and was originally given to the famous Cedar of Lebanon, and other related species. These trees, known to botanists as Cedrus, have needles like spruce, and upright cones. Several closely-related species grow wild from Morocco, around the Mediterranean, and through Turkey as fast east as the Himalayas. They don’t really look like arborvitae trees at all, but with a limited vocabulary of tree names, Thuja was called ‘cedar’, perhaps because they both have aromatic wood. That fact would have been more important to most people than the shape of the leaves.

Smart gardeners use ‘arborvitae’, or ‘thuja’ for the Thuja trees, and ‘cedar’ for the Cedrus trees. That way there can be no confusion.

Western Redcedar

This majestic tree is one of the parents of Thuja Green Giant. It grows through Western North America, in Oregon, Idaho, Washington state and British Columbia. It is a giant of a tree, reaching over 200 feet tall in the wild, and living for almost 1,500 years. Native Americans built their totem poles and war canoes from it, which is why it is sometimes called ‘canoe cedar’.

This tree was discovered in the 1790s by Taddaeus Haenkel, who, despite his name, was part of the Spanish expedition of Alessandro Malaspina. On a voyage of discovery, the group sailed around the world for five years. When the expedition was in Mexico, Haenkel travelled north, and collected many plant specimens. When they returned to Spain, Malaspina was jailed for sedition, and most of their work lay unsorted for about 70 years. Some pieces were distributed, and specimens of this tree ended up with the English botanist James Donn, who published the first description in 1824. It was 1853 before seed was brought to England by William Lobb, who worked for the famous English plant nursery, Veitch. Those were the first plants grown in gardens, and some still stand in the UK.

It would be much better if we called western redcedar ‘western arborvitae’, which would then immediately connect us with its eastern cousin, and avoid confusion with the true cedars. No wonder botanists prefer to use those Latin names.

Japanese Arborvitae

This much rarer tree is the other parent of Thuja Green Giant. Called by botanists Thuja standishii, it is the only Thuja outside North America. Its presence in Japan is part of a much larger phenomenon of closely-related plants occurring on both sides of the Pacific Ocean. It is assumed that the continents were once much closer together, allowing plants to travel as seed from one side to the other. Eventually, as they separated, the related plants on both sides went their own ways, developing into different species.

The Japanese arborvitae (never called a ‘cedar’) is a medium-sized tree, usually only growing about 50 feet tall, but sometimes reaching 100 feet. It is used in Japan to make furniture, but its use was limited, because it was declared the property of the Emperor, and common people could therefore not cut it down. Because this preserved it from being cut down a lot, it is not greatly threatened by extinction from logging, as so many of the world’s trees are. It was admired and grown in gardens, which is where, in a Tokyo garden, the plant collector Robert Fortune saw it in 1860 and brought it to England. Its rather odd name comes from Standish’s Nursery, near the famous racing town of Ascot, where Fortune’s seeds were grown. It was given its botanical name in 1867, by George Gordon, an expert on conifers.

Thuja Green Giant

Now all this will not help you grow your Thuja Green Giant at all, but that is an easy task anyway, with such a vigorous and healthy tree. However, it will give you some interesting factoids to share with your neighbors when they come over and something to think about when you are out trimming your beautiful hedge.