I love the elder. I love to walk beneath its white flowers in the spring, catching whiffs of anise, orange blossom, and bell pepper. I love its late summer berries, drooping heavily on broad stem clusters loaded with glistening black jewels. And I’m in awe of its danger—the toxicity of its branches, leaves, and bark, coursing through pink and purple stems. The elder is a tree with so much vitality. It ushers in the summer with flowers, then sees it out again with berries.

To learn more, I turned to the most extensive collection of information about plants in beer that I know: Stephen Harrod Buhner’s “Sacred and Herbal Healing Beers.”

Curiously, all the historical recipes that he collected for ebulon required boiling the elderberries. That is an uncommon technique. Today, most brewers add berries to the fermentor after primary fermentation is complete. That keeps the delicate flavors and aromas of the fruit intact. Boiling breaks down some of those volatile compounds.

But elderberries are a different kind of fruit. The tannic berries contain cyanogenic glycosides, which can lead to cyanide poisoning. Chewing and digesting the berries hydrolizes those glycosides, producing toxic hydrogen cyanide. The same reaction occurs when people consume other foods that contain cyanogenic glycosides, such as almonds, apple seeds, cherry and plum pits, apricot kernels, and cassava. Some of those foods aren’t safe to eat, while others, like elderberries and cassava, one of the world’s most important nutrient-dense foods, must be processed first.

(I should note that there is some debate about how much cyanide raw elderberries actually create in the body when consumed raw. If you’re curious, keep an eye out for a forthcoming paper, which seeks to dispel some anecdotal evidence with scientific analysis of the skins, seeds, juice, and pulp, from Andrew Thomas, Research Assistant Professor at the University of Missouri, Southwest Research Center.)

We know for sure that heating the berries for an extended period of time neutralizes the cyanogenic glycosides and the possibility that they could create hydrogen cyanide. That’s why most recipes you see for elderberries, like syrups or jams, require boiling the fruit. After cooking, elderberry products are perfectly fine to eat.

It may be that our forebears discovered that boiling elderberries made them safe, which is why they boiled them in beer. In his book, Buhner points out that the word “ebulon” relates to a European species of elder tree with the scientific name Sambucus ebulus. Ebulus, he notes, comes from the Latin ebullire, which means “to boil out.”

What I found, too, after following those recipes and innovating a bit in our brewery, is that the powerful tannins in the skins add a strong bittering quality in the boil, not unlike the tannins that come from long skin contact on grapes when making red wine. In fact, the beer is so bitter after boiling and fermenting that it requires nearly nine months of conditioning before it is drinkable. But tannins also help prolong a beverage’s life. That’s why some red wines can keep for decades. We embrace the age-worthiness of the fruit and put our beer in an oak barrel after primary fermentation, as part of an abbreviated solera aging program.

Using the solera technique, a small portion of beer is removed and bottled each year, and the barrel is then topped off with new beer. That means we leave a portion of the original beer in the barrel as the years go on. That helps create complex oak character and oxidization, which enhances the barleywine-like weight, and, yes, port wine-like character of the finished beer. The oldest beer in our barrel is five years old, and the mixture gets more complex and exciting to my senses every year. Hopefully, in the end, what we make is a concoction worthy of a magnificent and ebullient tree.