Good things come to those who wait. Its true that Ironwood (Olneya tesota) or Foothill Palo Verde (Cercidium Palo Verde) are not the fastest growing species in the arid landscape pallet. Few trees better illustrate the unique combination of beauty and austerity that is the Sonoran desert. Both trees are slow growing, have beautiful spring flowers, graceful, curved trunks and require special care and consideration when used in landscape setting.

IRONWOOD: Ironwoods take their name from the dense, dark and heavy wood the tree produces. The wood is prized for carving and as firewood. It is native to the southwestern US and northwestern Mexico. In native settings it is typically found on rocky well draining slopes and plains at elevations below 2500 feet. Foliage is gray green and semi-evergreen with leaves dropped in response to long drought or freezing temperatures. Trees are hardy to 20 degrees but can sustain considerable foliage and small twig damage at 25 degrees. Mature trunks and branches are pale gray/white while immature wood is pale green and armed with many, sharp, curved thorns.

The natural growth habit is multiple trunks with branches extending to the ground. Natural forms are excellent in plantings that transition landscape back to undisturbed desert or when used as a security planting. To create a more cultivated appearance trees will require selective pruning. On existing specimens, such pruning should be done gradually over time as trees may be injured by heavy pruning. Nursery grown Ironwoods require little if any pruning. Trees produce clusters of small pink to purple flowers from April to June. Mature trees can grow to 30' by 40' but typically are 15' to 20' tall and as wide.

Ironwoods are highly adapted to the hottest environments in the Sonoran desert. Trees will not thrive in lawns or when mixed with landscape plants that require regular winter irrigation or summer irrigation more frequent than once a month. No single factor contributes to the death of Ironwoods more than does over irrigation.

FOOTHILL PALO VERDE: Foothill Palo Verde is the smallest of the Palo Verdes, typically maturing to 12' to 15' tall and wide. It is native to the American southwest, Baja and Sonora, Mexico at elevations from 500 to 4000'. It grows on rocky slopes, desert foothills and mesas. Leaves are yellow green and very small (the Latin species name microphyllum means tiny leave). Half inch pale to bright yellow blooms appear beginning in April or May. Flowers usually last until the onset of 100 degree temperatures.

Established trees in the landscape can survive on seasonal rainfall. The trees are hardy to 15 to 17 degrees but like Ironwoods will not tolerate excessive irrigation. All branches, mature and immature, end in a sharp, rigid spine. These spines limit the use of Foothills around walkways and play areas. Leaves are widely distributed along these branches giving the leaf canopy a pale green, transparent quality. Drought or severe cold will cause leaf drop. Trees will need some pruning to shape the canopy and accentuate the trunk structure. Most specimens are multiple trunked. Some single trunked trees are produced in the nursery.