Ask the "barometer bush," Leucophyllum frutescens. 

Have you seen the barometer bush in the Arid Dome? It has silvery bluish-green leaves. Plants that grow in dry conditions have a variety of ways to minimize water loss, such as the spines of cacti. The barometer bush reduces water loss by having very small leaves that are covered with fine, white hairs. Its scientific name comes from the Greek: Leuco-white -phyllum leaf. It goes by several additional common names including Texas sage, Texas ranger, or cenizo, which means ash-colored in Spanish.

Common names can cause confusion because they vary from place to place and can be similar or identical for plants that are completely unrelated. Texas sage is unrelated to the herb or ornamental sages (Salvia) of the mint family. It is also unrelated to the sagebrush (Artemesia) of the old Westerns which belongs to the aster family.

You can see what plants it is related to by observing its abundant purple flowers (photo credit: Clarence A. Rechenthin @ USDA-NRCS PLANTS Database). The small flowers are funnel-shaped, with five lobes and two lips. Color ranges from white to magenta to purple, although it is mostly purple in the wild. The spotted throat of the flower, similar to its relative foxglove, is thought to serve as a nectar guide for pollinating insects. Other related plants include Indian paintbrush, mullein, snapdragon, and speedwell (Veronica). Horticultural varieties are planted across the southern states, especially in the Southwest and Florida.

Why is it called the barometer bush? When the atmosphere changes from arid to high humidity and rain, flowering is triggered. This is a survival trait for successful seed production. Texas sage can be propagated from cuttings or seeds. It cannot tolerate very cold winters, however it does very well in dry regions and is suitable for xeriscaping. It prefers strongly alkaline soils and tolerates both salty soils and deer.

It provides intermittent splashes of color through summer, often after a rain -- hence the cIt provides intermittent splashes of color through summer, often after a rain -- hence the

Image:  _{http://plants.usda.gov/java/profile?symbol=LEFR3}