Encelia farinosa

 Encelia farinosa (brittlebush) (incienso)

Asteraceae

• One way in which the leaves of desert plants reduce the amount of solar radiation they receive is through leaf surface hairs, scales, or waxes that increase the reflectance of solar radiation. Pronounce grey or white leaves reflect more light than green or greenish leaves and thus have reduced levels of light energy reaching the leaf structures. One of the best regional examples is seen with brittlebush. In the spring, when soil water is available, brittlebush produces relative broad and thin leaves with a modest coverage of hairs (pubescence) on their surface. As drought stress gradually increases, brittlebush forms smaller and thicker leaves with a dense covering of silver hairs. Looking in cross-section the mass of hair on both the upper and lower leaf surfaces may be greater than the thickness of the leaf itself. These reflective hairs cut up to half of the solar radiation that would otherwise be absorbed by the leaf surface. The result is a cooler leaf with a reduced loss of water through transpiration, but at a cost of reduced rates of photosynthesis.
• Third in importance is brittlebush. It is a familiar and conspicuous shrub that colors broad areas of the desert plains in the spring with its large, radiate yellow flowers. It is easily recognized as a tall shrub up to 5 feet in height, often with multiple main stems, displaying large lemon-yellow sunflowers. Brittlebush is a classic species for describing seasonal leaf dimorphism. The early spring leaves of brittlebush are broad and thin with a light white pubescence. As the season progresses and water stress increases, the newly produced leaves become smaller, thicker, and have and increased density of hairs on their surface. Leaves are ultimately shed under conditions of summer drought stress. A unique character of brittlebush, in comparison to its related species, is that several flower heads are born on each stem, Other Encelia species have just a single flower head per stem. 
• Brittlebush frequently forms hybrids with button encelia (Encelia frutescens), as well as with California encelia (Encelia californica).
• Although it avoids higher higher elevations above 3, 000 feet, the range of brittlebush extends from creosote bush scrub in Death Valley across the Mojave Desert and all through the Sonoran Desert into Mexico. Over this range it shows preference for rocky well-drained soils on south-facing slopes. "California Desert Plants, Philp W. Rundel, Robert J. Gustafson, Michael E. Kauffmann."
• Brittlebush forms the most extensive late winter flower show in Arizona. In frost-free areas, blossoming begins in November, and sometimes persists to mid-May. Flowering is most intense in March and April. Many insects are attracted to its long-stalked, sunflower-like bouquets. On volcanic hillsides, the gold contrasts vividly with the black rock. Brittlebush foliage changes radically, depending upon seasonal moisture. The first new ones after a rain will be larger and greener, but as the soil dries, greyish leaves a hundred times smaller in area will be produced. These latter leaves will persist under mild drought, whereas the first ones will be dropped to reduce water loss. A gum exuded from the stems can be burned as an aromatic incense, hance the Spanish name incienso. Direct sowing; seeds in pots for transplanting/ No treatment needed/Time of planting: spring-summer. "Arizona Highways Presents Desert Wildflowers, 1988".
• Perennial bush with whitish to grayish green foliage; becoming leafless during drought. Bright yellow. daisy-like flower heads on long stalks are produced at various times of the year, generally in spring and again with the summer rains. It is one of the most common and conspicuous wildflowers in the Sonoran Desert and seasonally turns the landscape yellow. Two varieties occur in the region: var. farinosa with all yellow flower heads and var. phenicodonta with a brownish disk and yellow rays. The latter is more common. Adhesives, Sealants, and Gums: the resin from this plant is not common, and exudes near the roots. It is dry and hard, often yellowish or dark in color. This resin was heated and used as a glue. It was sometimes used for desert floor on the mainland and Tiburon Island. Medicine: tea made from the stems was taken as a remedy for colds and also during a difficult delivery. When the mother was given this tea the baby was said to dislike the plant's "bad odor" and was born quickly. Tea made from the roots was used to cure toothache and diarrhea. "People of the Desert and Sea, Ethnobotany of the Seri Indians. Richard Stephen Felger and Mary Beck Moser".