Olneya tesota

 Olneya tesota (ironwood) (palo fierro)

Fabaceae

• It is a moderate-sized, winter deciduous tree that grows 15-30 feet in height with a spreading crown and this scaly gray bark. Ironwood is sensitive to cold temperatures and does not extend into the Mojave Desert or higher elevations of the Sonoran Desert in Arizona. It favors broad washes and middle slopes of large alluvial fans, often occurring with blue palo verde (Parkinsonia florida). The pinate gray-green leaves of ironwood features a pair of sharp, curved spines beneath each leaf along the major branches and trunk of the tree. Although many desert trees serve an important ecological role as nurse plants-aiding in the establishment of seedlings. Ironwood is also a legume with root nodules that fix nitrogen. The name ironwood come from the extremely high density of its wood, which is so dense that it will sink in water. "California Desert Plants, Philip W Rundel, Robert J Gustafson, Michael E Kauffmann."
• Ironwoons often act as a nursery for tender, young saguaros which, many years later, outgrow or even kill their protective cover. --- The greyish-green leaflets, combined with blossoms varying from deep violet to white, give a pale purplish cast to the washes and slopes where ironwood lives. Ironwoods obtain heights of 30 feet and produce one of the heaviest woods in the world. This fine hardwood is used for radiantly polished woodcarvings of desert and sea animals by the Seri Indians. At the northern edge of their range, ironwoods freeze often and become more sparse. They seldom extend above 2, 500 feet. Bee pollinated, they have an extremely compact flowering season ranging from three weeks to as little as six days. This season begins in mid-March on the Mexican border but is initiated later, around mid-May, farther north or at higher elevations. "Arizona Highways Presents Desert Wildflowers 1988"