From Pine Tree to Pine Tar (and a bit about baseball)

Scots pine (Pinus sylvestris) is a Eurasian native, distributed across Europe into Eastern Siberia. It is the national tree of Scotland, and the only native pine in northern Europe. Human activity has pushed native populations to extinction; while, at the same time, appreciation for this tree has led to widespread introduction in other parts of the world. Like other pines, humans and Scots pine have a long relationship going back millennia. Pines are incredibly useful trees, which explains both the overexploitation and mass planting of Scots pine.

Scots pine (Pinus sylvestris) via wikimedia commons

In Sweden and other Scandinavian countries, Scots pine not only has a long history of being used as a building material, but also for producing pine tar. As the name suggests, pine tar is a dark, sticky substance extracted from pine wood. Wood tar production dates back centuries and has been made from a number of tree species, including pines and other conifers as well as deciduous trees like birch and beech. Wood tar has myriad uses – as an ingredient in soaps, shampoos, and cosmetics; as medicine; as a food additive; as waterproofing for ships, roofs, and ropes; in hoof care products for horses. It’s no wonder that as demand for pine tar increased in Scandinavia, it became a cash crop for peasants, earning it the nickname “peasant tar.”

Pine tar soap – a decent soap if you can tolerate the intense smell. Regarding the smell of pine tar, Theodore Kaye writes, “The aroma produces reactions that are as strong as the scent; few people are ambivalent about its distinctive smell.”

A study published in the Journal of Archaeological Science examines small and large funnel-shaped pits in Sweden determined to be used for making pine tar. The smaller pits date back to between 240 – 540 AD, the Late Roman Iron Age. They would have been used by Swedes living in small scale settlements. The larger pits date back to 680 – 1160 AD and signify a shift towards large scale production during the Viking Age. As the centuries proceeded, Sweden became a major exporter of pine tar. Their product set the standard. Even today “Stockholm Tar” refers to pine tar of the highest quality.

As Europeans colonized North America, they were introduced to several new pine tree species from which to extract pine tar, including longleaf pine (Pinus palustris), a southeastern native with exceptionally long needles. Pine tar production was especially prolific in the southeastern states, thanks in part to the abundance of longleaf pine and others. North and South Carolina were dominating production by the 1800’s, which helps explain North Carolina’s nickname, The Tar Heel State.

Extracting pine tar from pine wood is fairly simple. The process is called destructive distillation. Pine wood is placed in a contained, oxygen-free environment and subjected to high heat. As the pine tar is released from the wood, the wood turns to charcoal. This is what was happening in the small and large funnel-shaped pits discussed earlier. Root pieces and stumps of Scots pine were placed into the pits. Brush wood was piled on top and then set on fire. As the brush burned, the pine wood below carbonized, and pine tar collected at the bottom of the pit. In larger pits, the pine tar was piped out and deposited into a barrel – a set up known as a pine tar dale.

pine tar dale illustration

Modern production of pine tar is done in kilns (or in laboratories). The concept is the same – wood is enclosed in the kiln, heat is applied, and pine tar drips from the bottom of the kiln. Heartwood, also known as fatwood, is the best part of the pine tree for making pine tar, particularly the heartwood of old stumps. Making pine tar is such a simple process that anyone can do it, and there are numerous tutorials available online.

My familiarity with pine tar comes from being a baseball fan. Pine tar is a useful, albeit controversial, substance in this sport. Batters have a variety of means to help them get a better grip on the bat in order to improve their hitting. Rubbing pine tar on the bat handle is one of them. However, according to Major League Baseball rules, anything applied to, adhered to, or wrapped around the bat to help with grip is not allowed past the bottom 18 inches of the bat. Pine tar is allowed on the bat handle, but if applied past that 18 inches mark, the bat becomes illegal.

pine tar stick for baseball bat handles

This rule goes mostly ignored; unless, of course, someone on the other team rats you out. Which is exactly what happened in 1983 to the Kansas City Royals in a game against the New York Yankees. Royals batter, George Brett, had just hit a home run, which put the Royals in the lead. It had been suspected for a while that Brett had been tarring his bat beyond the legal limit, and this home run was the last straw for Yankees manager, Billy Martin. He brought the suspected illegal bat to the attention of the umpires, and after measuring the bat’s pine tar stain they found it to be well beyond 18 inches. The home run was recalled, and the Yankees went on to win the game.

It doesn’t end there though. After a repeal, it was decided that the dismissal of the home run was the wrong call. If an illegal bat is in play, it should be removed. That’s all. The home run still stands. The Royals and Yankees were ordered to replay the game, starting at the point where Brett had hit his home run. This time the Royals won.

This saga is well known in baseball. There is even a book all about it, as well as a country song and t-shirts. But that’s only part of baseball’s pine tar controversy. While batters are allowed to use it on their bats, pitchers are not allowed to use it to better grip the ball while pitching (however, they can use rosin, which curiously enough, is also made from pine trees). Of course, that doesn’t stop them from trying to get away with it. Sometimes they get caught, like Michael Pineda infamously did in 2014. There are arguments for allowing its use – and perhaps in the future the rules will change – but for now pine tar use by pitchers remains prohibited.

Further Reading – Medicinal Uses for Pine Tar:

Field Trip: Bergius Botanic Garden and Copenhagen Botanical Garden

There are very few downsides to working at a botanical garden, but one of them is that the growing season can be so busy that taking time off to visit other botanical gardens when they are at their peak is challenging. Case in point, my visit to Alaska Botanical Garden last October. Another case in point, this December’s visit to a couple of gardens in Scandinavia.

That’s right, Sierra and I took a long (and much needed) break from work and headed to the other side of the world for some fun in the occasional sun of Denmark and Sweden. While we were there we visited two botanical gardens, one in Stockholm and the other in Copenhagen. Considering we were there in December, we were impressed by how many things we found all around that were still blooming. We were also impressed by how much winter interest there was in the form of seed heads, spent flower stalks, and other plant parts left in place, as opposed to everything being chopped down to the ground as soon as fall arrives (which is often the case in our part of the world). We may not have been there in the warmest or sunniest time of year, but there was still plenty of natural beauty to capture our attention.

Bergius Botanic Garden

The first of the two gardens we visited was Bergius Botanic Garden (a.k.a. Bergianska trädgården) in Stockholm, Sweden. It is located near Stockholm University and the Swedish Museum of Natural History. It was founded in 1791 and moved to its current location in 1885. It was immediately obvious that the gardens were thoughtfully planned out, particularly the systematic beds in which the plants were organized according to their evolutionary relationship to each other. The extensive rock garden, which was a collection of small “mountains” with a series of paths winding throughout, was also impressive. Since we arrived just as the sun was beginning to set, we were happy to find that the Edvard Anderson Conservatory was open where we could explore a whole other world of plants, many more of which were flowering at the time.

Walking into Bergius Botanic Garden with the Edvard Anderson Conservatory in the distance.

Sierra poses with kale, collard, and Brussels sprout trees in the Vegetable Garden.

seed heads of velvetleaf (Abutilon theophrasti)

corky bark of cork-barked elm (Ulmus minor ‘Suberosa’)

pomelo (Citrus maxima) in the Edvard Anderson Conservatory

Camellia japonica ‘Roger Hall’ in the Edvard Anderson Conservatory

carrion-flower (Orbea variegata) in the Edvard Anderson Conservatory

Cape African-queen (Anisodontea capensis) in the Edvard Anderson Conservatory

Copenhgen Botanical Garden

The Copenhagen Botanical Garden (a.k.a. Botanisk have) is a 10 hectare garden that was founded in 1600 and moved to its current location in 1870. It is part of the University of Copenhagen and is located among a series of glasshouses built in 1874, a natural history museum, and a geological museum. Unfortunately, the glasshouses and museums were closed the day we visited, but we still enjoyed walking through the grounds and exploring the various gardens.

A large rock garden, similar to the one at Bergius, was a prominent feature. We learned from talking to a gardener working there that since Denmark is not known for its rich supply of large rocks, most of the rocks in the garden came from Norway. However, a section of the rock garden was built using fossilized coral found in Denmark that dates back to the time that the region was underwater.

Another great feature was the Nordic Beer Garden, a meticulously organized collection of plants used in beer recipes from the time of the Vikings to the Nordic brewers of today. Even though the majority of the plants in this garden were dormant, the interpretive signage and fastidious layout was memorable.

Walking into Copenhagen Botanical Garden with the Palm House in the distance.

lots of little pots of dormant bulbs

seed head of Chinese licorice (Glycyrrhiza echinata)

fruits of Chinese lantern (Physalis alkekengi)

alpine rose (Rhododendron ferrugineum)

Viburnum farreri ‘Nanum’

seed head of rose of Sharon (Hibiscus syriacus)

pods exposing the seeds of stinking iris (Iris foetidissima)