|Triangleleaf Bursage (Ambrosia deltoidea)|
DESCRIPTION: Small shrub to 2'. Leaves simple, toothed, triangular-shaped grayish-green to 1.25" long (compare to Brittlebush and Canyon Ragweed). Flowers bloom Dec. - April and are greenish, small (0.25" or less), and without petals. Fruit is a small bur that sticks to clothing (and fur). Compositae (Sunflower) Family.
NATURAL HISTORY: This is probably the most common shrub in the desert areas immediately around Tucson. Flowers are wind-pollinated and are one of the major causes of hayfever in the spring (sometimes called "burrobush or "rabbitbush" in pollen reports). Serves as a nurse plant for many desert cactuses (e.g., Fishhook Pincushion) and is commonly a host for Ratany. In times of drought, Triangleleaf Bursage will drop its leaves (drought deciduous) and appear dead.