Acacia caven (Espino Caven) is a South American native that shares many traits with familiar, southwestern natives like Sweet Acacia and Native Mesquite. In central South America (Peru, northern Chile and Argentina), where it is the second most widely distributed native tree, A. caven is called Espino Caven, Espinillo and Amorito. It is found growing in several forms including as a hedged shrub (3 to 6 feet tall) and small tree (6 to 8 feet tall), but can ultimately reach a height of 25 to 30 feet. Botanically it is closely related to Sweet Acacia, (Acacia smallii) sharing similar growth habits, flower color, shape, thorns and exhibiting high genetic variability. This variability may be due in part to it’s wide geographical distribution across a thick band of South America. At least 6 varieties of A. caven are recognized in South America, each tending to be geographically isolated. In Chile’s semi-humid regions, large, nearly pure stands of Espino are found, similar to bosques of native mesquites in southern Arizona or southern Texas. The tree has a broad spreading growth habit and produces fragrant fruit. Bright yellow, ball-shaped flowers are produced in the early spring prior to the emergence of new leaves. Flowers are densely arranged along the surface of the branches, similar to Sonoran Palo Verde (Cercidium praecox) or Twisted Acacia (Acacia schaffneri). Trees can be found in native settings growing from sea level to over 9000 feet. Trees tend to thrive near towns and cities, invading cultivated fields and abandoned pastures. Its potential as a substitute for Sweet Acacia initially drew the interest of wholesale tree growers. Its adaptability to an array of growing conditions and growth and horticultural characteristics makes it an excellent addition to the desert landscape palette. In tests conducted in Tucson it tolerated temperatures of 15 degrees F with no significant damage. Its natural growth habits strongly suggest that the tree would be well adapted to planting in groupings to create small bosques, as a perimeter planting or as individual specimen trees, placed strategically to take advantage of the flower color and fragrance.

Tecoma garrocha (Hieron) is the Argentine cousin of the more familiar Tecoma stans (Yellow Bells). Perhaps the most obvious difference from Yellow Bells is the deep yellow-orange to orange color of the flowers, borne in clusters on the terminals of new branches. Flowers appear from early spring to, in some locations, late fall. Flowering typically stops with the first freeze. The foliage is deeper green and denser than T. stans, with serrated-edged, lance-shaped leaflets. Depending on the severity and duration of freezing temperatures, plants may mature to heights of 10 to 20 feet tall, with plants in frost-free or protected areas growing tallest. Limited experience in the Phoenix metro area suggests that Hierons are hardy to 20 degrees F. Some frost injury to branch tips has been observed at temperatures below freezing. The roots are very cold hardy so even plants that freeze to the ground grow back rapidly in spring. Garrocha grows best in full sun and well-drained soils and can tolerate severe pruning during the winter. Winter pruning helps shape the plant and encourages the development of abundant new wood that will supports additional flowers. Some have mistakenly identified this plant as a hybrid with T. stans. T. garrocha is a legitimate, recognized species that produce true to type from seed. With tightly spaced, nearly vertical stems, the plant has a columnar, upright growth habit making it an ideal screening or perimeter shrub. Individual plants can be used as specimens, color accent shrubs, or against walls and structures. Its striking summer flowers are a welcome addition to desert landscape designs.