Scientific: Erythrostemon gilliesii (formerly 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 E. gilliesii confused with Poincianella 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 even if it seems like every few years they are arbitrarily changed by some new metric of phylogenic classification.
Family: Fabaceae (Leguminosae)
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: Er-i-thro-STEM-on 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 and open 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, wispy, 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 Caesalpinia pulcherrima. In Phoenix, the 'desert bird' is partially to fully deciduous during the coldest winters.

Light: Full sun

Soil: Tolerant, but regular fertilization will increase foliage canopy density which is otherwise typically sparse to open.

Watering: Definitely needs some summer water in Phoenix.

Pruning: Head back lightly after bloom, but only as needed to promote a more excellent shape. Unlike Caesalpinia 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-sized, but very open-canopied and sparsely-foliated accent plant. It attracts hummingbirds and also evokes semi-arid, subtropical connotations of an exotic beachside vacation along the Pacific coast of wonderful Mexico.