There’s a humorous saying among some beer lovers that the bean stalk in the English folktale “Jack and the Beanstalk” was really a hops plant.

Like the fictitious giant beanstalk that soared into a fantasy land in the sky, hops plants are fast-growing vines that can climb as much as a foot a day, Julie Jenney (at right) told a Botany of Beer class hosted by Atlanta’s GardenHood nursery in January. “Hops are the spice of beer and they’re great over a salad!” she enthused.

Julie JenneyJenney is the educational programs coordinator at the Scott Arboretum of Swarthmore College in Swarthmore, Pa. She got the idea for the class a few years ago when she and Tim Boland, executive director of the Polly Hill Arboretum in Martha’s Vineyard, Mass., talked about how they could come up with a class about beer that they could legitimately work on during their day jobs.

“Tim came up with the idea for Botany and Beer,” Jenney said. Their first class sold out, but she said Tim told her “If you want to do this on your own, take it and run with it.” She did exactly that, and the class has remained a popular offering at garden institutions since.

Readily admitting that she has a passion for gardening and a fine brew, Jenney mixed wit and humor in the two-hour Atlanta class as she explained the botanical components of beer and why the shape of glasses and food pairings for different beers matter.

“Making beer is like gardening,” she said. “Just as there are always more plants to grow, there are always more craft beers to try.” And brewmasters have found plenty of plants, especially members of the grass family, such as wheat and barley, fruits, spices and, of course, hops, to make craft beers.

Hoppy beers

Nowhere does her passion for plants and beer show through more than when she talks about hops, especially when she explains what it means to be “scratched by the hops.” Hops, in this case Humulus lupulus, is one of the three species of hops and the only one of the three to be used to make beer. The plants have no visible thorns, but the vines (bines, actually, because the plant climbs by shoots rather than tendrils) and leaves will leave red scratches on hands and arms a few minutes after handling. Supposedly, once hop growers have been scratched by the hops plant, hops are in their blood and they’re in the business for life. Jenney thinks the same is true of those who drink “hoppy” beers. Once they start liking them, they can’t get away from them.

The parts of the hops plant that are used in brewing beer are the pine-cone looking flowers, or strobiles, of the female plants of Humulus lupulus. They play a big role for their relatively small size, adding aroma, flavor, and bitterness that counterbalances the sweetness of the malt.  They also have antiseptic properties that centuries ago kept the unrefrigerated yeast culture from souring.

Hops plants are dioecious, meaning there are male and female plants. Because the male cones have little to no lupulin, the source of hops’ flavor, hops farmers plant only female plants. Hops are also photoperiodic, which means day length is critical to vegetative growth and flowering. These plants require a support such as a string or trellis but won’t attach to a wall like a climbing fig. While they like full sun, they don’t tolerate heat well.

The flavor of hops comes from the waxy substance lupulin, which are golden globules on the stem, or strig, which is what holds the leafy parts of the cone together. The globules, or glands, contain hard and soft resins and oils. The soft resins include acids that contribute to bitterness. The oils add flavor and aroma.

The aromas from hops can be familiar and surprising and range from floral to citrus, fruity, vanilla, cinnamon, cloves, white-wine-like, piney, spicy, tarragon, lavender, smoked bacon, caramel and almonds.

Centuries ago, hops began replacing gruit, a mixture of herbs including some that were mildly to moderately narcotic, as a way to flavor beer. Gruit ale was said to be a highly intoxicating stimulant for the mind that created euphoria and enhanced sexual drive, Jenney said. Hopped ale that replaced the gruit was said to be quite different, Jenney added. Supposedly it put the drinker to sleep and dulled sexual desire.

Pale ales and India Pale Ales (IPA) are examples of hoppy beers.

Beer ingredientsBelgian beers

Belgian beers have a wide variety of strengths, colors, and flavors that can be derived from a range of yeasts, sugars (honey and syrup in addition to the sugars from the malt), and often unmalted grains like oats, wheat and spelt.

Dubbels are dark in color due to the malts used and the sugars that are often caramelized. Tripels have three times the malt of a Trappist simple beer and are light in color due to the pale malts used and candy sugar, which not only lightens the body of Belgian beers but also adds alcoholic aromas and flavors. Quadrupels are bolder and stronger than their Dubbel and Tripel sister styles and have a rich, malty taste.

Yeasts are the real star of these beers, Jenney said. Yeast, which is a single-cell fungus, aggressively turns sugar in to alcohol. To envision how this works, she says to think of the yeast as Pac Man gobbling up the sugars in the wort and burping out carbon dioxide to create alcohol.

If you think Dubbels, Tripels and Quads leave you with a hangover, there’s a reason why, said Jenney. It’s the sugars. They increase the alcohol content.


Rauchbiers are beers with a smoky flavor that is gained by drying malted barley over an open flame of beech-wood logs in a kiln. Barley is the seed of the barley plant. Malted barley is barley that has been allowed to germinate, or sprout.

Barley is a great brewing grain because it contains a large reserve of starch that can be converted into sugar and a husk that makes a perfect filter bed, said Jenney, adding that it also contains enzymes that make this possible without adding anything but hot water. It is possible to produce two malts of similar color but different flavors by varying the amount of moisture content during kilning.

With the advent of technology that allowed for mass production of beer, almost all of the smoke kilns have vanished. Aecht Schlenkerla Rauchbier in Bamberg, Germany, is one brewer that has preserved the old tradition. During a tasting at the class in Atlanta, one attendee exclaimed that the beer has the flavor of a Virginia smoked ham, minus the saltiness.

Porters and stouts

In the first part of the 19th century, stout was simply another name for the strongest version of a porter. Brewers even used the same recipe; the only difference was that they used less water to mash the stouts so the stouts would be stronger than the porters.

The recipes began to diverge in the second half of the 19th century when London brewers began changing the type and quantity of malts to make stouts sweeter and less dry than the porters. Recipes took another fork in the road with the beginning of the craft beer movement in the 1970s. With 250 years of brewing history as a foundation, brewers now make porters and stouts to varying degrees of strength and you can now find a porter that’s stronger and darker than a stout.

The roasted flavor and dark color of porters and stouts comes from the many varieties of roasted malts – which comes from barley. Samuel Smith’s Oatmeal Stout from England is almost opaque. It originally was described as nutritional on its label and was used, in part, as a drink for lactating mothers.

The Botany of Beer road show

Jenney will present the class in several other locations around the country this year. Her schedule at this time is:

  • April 12, Charleston Horticultural Society in Charleston, S.C.
  • July 25, Coastal Maine Botanical Garden with Boland in Boothbay, Maine
  • July 27, Polly Hill Arboretum with Boland.
The classes include a tasting of different beers. There is a fee to attend to cover the cost of the beer. For information about the cost of the events this spring and summer or the times they will be held, contact the venue in your area.

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Photos: Matt Jones; MNN tease photo: Shutterstock
The botany of beer
Brewmasters have found plenty of plants in addition to hops — such as wheat, barley, fruits and spices — to create their craft beers.