During the record-breaking heat of summer 2023, some Texans put their hopes of rainfall in the flowering of a silvery-gray shrub. An evergreen native to West Texas, South Texas, and the Edwards Plateau, Texas sage has small silvery-gray-to-green leaves and a loose form, unless it’s trimmed into a hedge. With this mild appearance, it usually blends into the surrounding landscape. But from time to time, the plant erupts with vibrant purple flowers, a color riot that many believe heralds rain. After months of brutal heat and cloudless skies, the blooming of the “barometer bush” can be a joyous occasion. But does this popular plant—the official native shrub of Texas—really have the power of prediction?

It’s complicated. There are no scientific studies on how rainfall affects Leucophyllum frutescens’s blooming patterns, so no one can say for sure. However, several experts say the plant’s blooming is triggered by high humidity or low atmospheric pressure. Though it does occasionally bloom ahead of rainfall—seemingly in anticipation of precipitation—more often it flowers after a shower.

Lydia Holley, the former president of the Henderson County Master Gardener Association, in East Texas, said the plant is nicknamed the “barometer bush” because of its apparent ability to take stock of barometric pressure, a measure of the weight of the atmosphere. Low atmospheric pressure is associated with rainfall. Holley said that Texas sage will occasionally bloom days prior to rainfall—presumably triggered by the dropping barometric pressure—but that it’s more likely to flower after it rains. Sometimes it just seems to get excited about miserably high humidity. So don’t expect this shrub to be a perfect meteorologist. (Other names for Texas sage include cenizo, silverleaf, Chihuahuan sage, Texas Ranger, and purple sage.)

Why would the plant time its blooming with rainfall? The desert species may be trying to maximize its survival, said Cathryn Hoyt, a supervisory park ranger at Big Bend National Park. Its native range, which includes portions of northern Mexico, is hot and prone to drought. Water is at a premium. “Water is such a rare and precious thing in the desert,” Hoyt said. “As soon as it rains, the plants are going to put on a flush of flowers so that they can reproduce. You’ve got to take advantage of it.”

Texas sage, which isn’t actually in the sage family, is an increasingly popular landscape plant. It is one of the few plants that seem relatively unfazed by the state’s capricious climate, including both our polar vortices and our seemingly endless days of triple digits. When not blooming, it makes for a handsome xeric border or backdrop plant. Gardeners can let it grow in its relatively unruly natural form or trim it into a more formal hedge. It also provides interest during the doldrums of winter. Holley said the plant’s evergreen qualities make for a nice contrast against barren branches. “You look out there, and everything looks so bare,” she said. “So, it’s really nice to have some evergreen accents in the garden.”

Texas sage also benefits wildlife. This dense desert shrub offers refuge to birds, including the mockingbird (the state bird of Texas), and the blooms provide nectar for pollinators, including butterflies and moths. Two species—the theona checkerspot and the calleta silkmoth—rely on cenizo as one of the primary host plants for their larvae.

But one critter, thankfully, isn’t a fan. Texas sage is deer-resistant, likely because its leaves and petals are blanketed with fuzzy bristles that may make it unpleasant to eat. Its distinctive scent—a mash-up of citrus and pine—may also discourage browsing, according to Dave Forehand, vice president of gardens at the Dallas Arboretum. “If you want a plant that’s going to survive in” deer-heavy areas, “that’s a great one to plant,” he said. “Whatever’s in that leaf is not something deer eat, which is pretty rare because they eat almost everything.” 

Another advantage for gardeners: Texas sage doesn’t require much watering, even in our drought-prone state. After the first year (during which you should water it once or twice a week), this hardy desert dweller is likely to thrive without much, if any, human intervention.

If you are looking to add this deer-resistant, dense, colorful, low-maintenance shrub to your garden, you can opt for different cultivars—plant varieties bred for specific traits—based on your preferences. The popular green cloud cultivar, which has bigger leaves and is greener than its silver-leaved counterparts, can reach six to eight feet in height. The compact variety is a shorter, five-by-five-foot shrub that has a rounder, denser, and more compact shape. Texas is also home to another, similar species, the Big Bend silverleaf. Native to, you guessed it, the Big Bend region, Leucophyllum minus also seems to anticipate rainfall, with milky purple flowers, but its leaves and stems are whiter and a bit thinner. 

Whether you’ve come to admire Texas sage for its premonitions, its petals, or its good ol’ Texas hardiness, when you see those purple flowers in bloom, you may want to reach for the umbrella.