In the oak forests of Missouri towering trees stand tall as sentinels, their bountiful sweet acorns providing sustenance for wildlife such as blue jays, black bears and wild turkeys, their sprawling canopies casting shade on the forest floor below. The state is home to 62,000 acres of forest with some trees more than 130 years old, many of which grow to more than 10 storeys tall. Missouri’s forests, and those of the central and eastern United States, are the whisky industry’s primary sources of oak.

We all know Bourbon barrels must be made from virgin American white oak, which is often referred to as Quercus alba. The truth is, Q. alba is just one of around 60 species of white oak growing in North America. With the rise of craft distilling and a renewed focus on the raw materials that contribute to whisky’s flavour, there’s a swell of interest in non-traditional oak species from Japanese mizunara to Hungarian oak, with one native American name in particular capturing the imagination of distillers around the world.

Quercus Muehlenbergii (pronounced mer-len-burg-ee), otherwise known as chinquapin, or chinkapin, is a species of American white oak that mostly grows in the same central and eastern areas as Q. alba, from Michigan to Alabama and Pennsylvania to Texas. Named after Lutheran pastor and amateur botanist Gotthilf Heinrich Ernst Muhlenberg, the oak is prized as a quality, durable hardwood by furniture makers. Visually, the oak is strikingly similar to Q. alba, making them difficult to discern.

The ubiquitous Q. alba is also often confused with swamp oak (Q. bicolor) and bur oak (Q. macrocarpa). While the word chinquapin is only now being slung about by distillery marketing teams as a point of difference, with such similar-looking species growing so closely together it’s not entirely unreasonable to assume these oaks, including chinquapin, have made been making their way into whisky casks undetected for decades. Once cut into staves, the only way to discern the species is through DNA testing.

“There’s only a few people who can distinguish [chinquapin] wood once it’s been sawn if you don’t see it in tree form,” says Don McGinnis, president of McGinnis Wood Products (MWP) in Cuba, Missouri.

Founded in 1968, the family-operated business is one of the few cooperages processing chinquapin oak.

“It always went in barrels, we just never separated it. Most people can’t distinguish it and so there’s always been a tree here or there. Once in a while the whisky people would get a barrel they’d call a ‘sweet barrel’, because the whisky was different. We always wondered whether it was because it had chinquapin in it.

“There’s never been an answer for that, because we have no real way of knowing. What we do know is there is a distinct flavour difference in the whiskies made out of different wood.”

McGinnis and his father Leroy (who remarkably still works at the cooperage at the age of 91) was one of the first to handle the species back in the 1990s during a project with the Scotch Whisky Research Institute (SWRI).

That research coincided with The Glenmorangie Company’s early experiments with maturing whisky in a variety of different styles of American oak, including chinquapin, burr oak, post oak (Q. stellate) and swamp oak, as well as German truffle oak. Dr Bill Lumsden, director of distilling, whisky creation and whisky stocks at Glenmorangie, recalls inheriting the stock when he joined the company in 1995. “These little different varieties were simply a curious side project and the main part of that work was to end up developing the perfect cask type for Glenmorangie – our designer casks.

“They had fallen into oblivion. So I locked a lot of these things away, nurtured them, sampled them and got them released.”

The whiskies were all laid down in 1993 and bottled in 2004-05 as a series of single casks. Glenmorangie 1993 Chinquapin Oak (Cask No. 1953; 57.3% ABV) was a limited run of 298 bottles sold exclusively through Heathrow duty free in November 2005 for £95 each.

Lumsden adds that the method of treating the barrels in the same way meant the team could pick out if there were any flavour differences.

“Having carried out all of these experiments, guess what? There were differences, but they were not huge. I reckon 50 per cent of people out there wouldn’t pick up a difference, although I felt there was, particularly between the burr, swamp and chinquapin.”

Lumsden describes the burr oak-matured whisky as having “this unbelievably big buttery taste”, while swamp oak had “more of a kind of earthy spiciness” and the chinquapin “more toffee notes”.

For Andrea Wilson, master of maturation at Michter’s, which uses whisky aged in chinquapin in its Bomberger’s expression, the oak helps extract more fruitiness from the spirit while adding a touch more tannin. “It’s a very interesting tree to work with and while we’re still learning all the different things we can get from it, chinquapin imparts an incredibly rich profile,” she explains. “It’s comparably priced to American white oak, but it’s a little bit more expensive simply because the loggers don’t really like to work with it. The tree doesn’t grow particularly straight so it makes it more difficult to harvest, and the cooperages have difficulty working with it.”

Chinquapin grows on rough terrain, usually limestone outcrops which loggers struggle to reach. As such it’s a slower-growing tree with softer wood, which results in more growth rings and allows for deeper penetration of the whisky. McGinnis air-dries its chinquapin for up to 36 months using the same approach for Q. alba destined for wine casks.

Spirit of Hven’s Henric Molin started using chinquapin in 2001, and says the oak gives his whisky a “nuttiness, an almond character”. Heavily charred chinquapin comprises 58.2 per cent of the cask make-up of the distillery’s Tycho’s Star expression, a significant chunk considering the availability of chinquapin is extremely low.

“We get enough to do maybe 1,000 barrels a year,” says McGinnis. “There’s not a huge amount of that tree growing.”

Today chinquapin is being explored by the likes of Raasay, GlenAllachie, Teeling and Jura, as well as American producers such as Heaven Hill, Brown-Forman and Michter’s. Although its story in whisky maturation is just getting started, with such low numbers of harvestable trees available, it will continue to be niche. That said, its use opens the gate for further exploration of flavours derived from the cask.

This article originally appeared here. 

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