Questions by kids: What does sagebrush look, smell and taste like

Note from the editor: Big Sagebrush (Artemisia tridentata) is toxic. Do not eat or ingest any part of a sagebrush plant. The sampling described in this article are conducted by subject matter experts, and should not be attempted.

Learning is all about asking questions, and children ask the best questions. Boise State is home to more than 1,400 faculty members and researchers who are eager to answer these amazing questions.

Today, Professor of Biology Jen Forbey answers a child's question: "What does sagebrush look, smell and taste like?

To answer this question, Forbey delves into the incredible ways that various animals (including humans) perceive this iconic Western species, and what we can learn from them. If we momentarily inhabit the senses of creatures such as Pygmy Rabbits, Pronghorns and Sage-grouse we discover that the scruffy, silvery-grey brush we pass by in our cars is actually very weird (and incredible).

At Boise State, Forbey studies sagebrush and the animals that feed on this plant in the unique Sagebrush steppe ecosystem. With her students, she listens to the chemical messages contained in sagebrush leaves and in the droppings from the animals eating sagebrush to learn about this important species.

How did sagebrush get here?

Sagebrush came from Asia over the snow bridge across the Bering Strait and co-evolved in North America with the megafauna like mammoths, giant ground sloths, and the American lion.

We know from the stomachs of fossilized horses from the Pleistocene Epoch (2.58 million to 11,700 years ago), that the herbaceous ancestors of sagebrush have been around since then, and that prehistoric horses ate sagebrush. Unlike many of the giant animals who took their last bites of plants at the end of the Pleistocene, sagebrush survived.

Since then, sagebrush has had to defend against the remaining hungry herbivores that did survive the pleistocene, like pronghorn and sage-grouse, a warming and drying climate, repeated volcanic eruptions, and wildfires. Out of these stressors, came a plant toughened by chemical defenses.

The result is a plant that tastes terrible and releases strong volatile warning chemicals to prevent interactions with animals. It does not need to attract animals to disperse its seed to reproduce. Instead, sagebrush seed is dispersed by the wind.

What does sagebrush look like?

Depending on who (or what) you ask this question, the answer can be very different.

To a human, this plant varies between low lying plants the size of a softball to large and scruffy "trees" as tall as a human adult. The top of sagebrush contains tall flowering stalks full of seeds reaching to the sky to help the wind disperse seeds. Plants vary in shades of grayish-green leaves that get replaced each year.

Winter leaves are smaller and have more consistent shapes compared to summer leaves. Some leaves have hairs and some have black glands dotting the surface that are full of perfumes. The trunks of older plants are often gnarled into interesting shapes and can be marked with yellow, orange and red lichens. Plants can be aged using tree rings and can live over 100 years.

Some sagebrush leaves emit UV light. These plants are actually more palatable and it's a signal to the animals that it's not as toxic as something that doesn't have those UV-producing chemicals in it. The UV plants are the ones that hungry herbivores like sage-grouse will want to eat, Forbey says. The droppings of sage-grouse also glow in UV, but only when they eat UV-emitting plants.

The UV plants tend to be smaller and at higher elevations, and the reason we think that they can get away by having this "I am tasty" signal is that plants that are short and at high elevations would normally be hidden under snow in the winter when animals rely on sagebrush for food. But now that we have less snow, they're becoming more vulnerable to hungry animals.

What does sagebrush smell like?

If you've been near sagebrush after a rain shower, or brushed against the plant, it releases strong smelling chemicals that some people say are spicy, earthy, piney and even medicinal.

When the plant gets damaged or when the rain hits it, it opens up glands, and then it releases volatiles (organic chemical cocktails) into the air. Each plant has a unique perfume. Other plants can sense these volatile perfumes, and respond by increasing their own chemical defenses in preparation for the danger that might be coming for them.

Essentially, these odors are released like an alarm, as if the plant is shouting to all of the nearby plants, "Defend yourselves! Something wants to eat or damage us!" Plants that are more closely related to the shouting sagebrush can hear the alarm call better and respond faster than less related plants.

How does sagebrush Taste?

Unrelated to the common sage (Salvia officinalis) found in the garden and spicerack, the wild and woody sagebrushes (Artemisia Genus) are inedible.

It's really, really bitter, and each plant's leaves give a different bitter taste in different places of your mouth, Forbey says. Even the "best" sagebrush, the ones that have a slightly minty taste are not something you would want to eat.

Forbey and fellow experts know how to taste sagebrush safely, by cutting off a piece of the plant that is no bigger than the head of a pin, chewing it and spitting it out.

Because of its unpleasant bitterness, very few creatures bother trying to eat the plant. And this awful taste is a big reason why the species has survived so long.

Today, some very hungry species that live near it (like Greater Sage-grouse, Pygmy Rabbits and Pronghorn) have evolved to know what tell-tale signs (like the UV glow) point to the least toxic plants, what parts of the plant to nibble on and exactly how much they can eat without experiencing a toxic reaction.

The tasty plants are not everywhere and instead offer herbivores a patchwork of "palatable islands". Once the palatable islands are found, the herbivores return every year to the same locations in winter to feed. These restaurants in the sagebrush sea likely play a critical role in annual survival and movement of sage-grouse, pygmy rabbits and ungulates.

Unfortunately, forces like wildfires are reducing the size and number of these palatable islands. But Forbey and partners are working to defend and grow the right sagebrush in the right locations so wildlife can continue to fill their bellies with the least toxic sagebrush and humans can continue to listen to sagebrush's chemical story of survival.

Read more about Boise State's sagebrush research

• Mapping the genetic footprint of big sagebrush
• Tapping the secrets of sagebrush genetics for restoration and sustainability
• The school bus in the sagebrush
• New study reveals mixed impact of population growth on the sagebrush steppe
• Mapping Idaho herbivores' salad bar from the sky

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