Scientific: Caesalpinia gilliesii
Common: There are many common names for this plant. They are in no particular order - bird of paradise shrub, bird of paradise bush, desert bird of paradise. Sometimes people get C. gilliesii confused with C. mexicana and call it yellow bird of paradise (even though the flowers have bright red stamens). This is problematic and demonstrates why the use of scientific names rather than common names to identify plants is important.
Family: Fabaceae
Origin: Native to Argentina and Uruguay, but has now naturalized in portions of the Chihuahuan and Sonoran Deserts in close proximity to inhabited areas.

Pronounciation: Say-sal-PIN-ee-a gil-ee-ES-ee-i

Hardiness zones
Sunset
12-16, 18-23
USDA 9 - 11

Landscape Use: Seasonal accent, quick background though canopy is too sparse to make a screen, nice tropical shrub for transition areas in oasis landscape design themes

Form & Character: Partially evergreen shrub, irregularly rounded and spreading, sparse, open, festive, warm, vulnerable

Growth Habit: Moderate growth to 8 to 10 feet tall with equal spread. This taxon has very brittle wood.

Foliage/texture: Leaves twice pinnately compound, leaflets to 1/4 inch and less, light green, graying with age, stems without spines but with well defined lenticels; fine texture.

Flowers & fruits: yellow flowers with red filaments on terminal spikes, fruit are green pods in terminal clusters turning to brown pods in summer that are heavy and weigh down branches.

Seasonal color: Festive yellow/red flower color in spring and fall

Temperature: Heat loving like C. pulcherrima. In Phoenix, the 'desert bird' is partially to fully deciduous during the coldest winters.

Light: Full sun

Soil: Tolerant. Regular fertilization will increase foliar canopy density which is otherwise typically sparse to open.

Watering: Needs summer water

Pruning: Head back lightly after bloom only as needed to promote a more excellent shape. Unlike C. pulcherrima, don't severely prune the 'desert bird' as it is slower to recover. Because the stem wood of this shrub is SO brittle, one can easily prune this shrub with bare hands!

Propagation: Seed

Disease and pests: White flies

Additional comments: The desert bird of paradise is a good, medium, open-canopied accent plant. It evokes semi-arid, subtropical connotations and attracts hummingbirds. The tanins found in the seeds of many Caesalpinia taxa are mildly toxic and if ingested might cause temporary gastrointestinal distress that usually subsides after 24 hours.