Parkinsonia microphylla aka Yellow Paloverde

Parkinsonia microphylla is a large shrub or small tree. It belongs to Fabaceae, the pea family. Its native range starts in southeastern California. It runs through Arizona and into northwestern Mexico. The plant grows in desert or dry shrubland. Its home thus lies in dry parts of southwestern North America. The RHS lists it as non-native to Britain and Ireland. It may take a shrub form or a tree form. It does not always have one clear shape.

The plant can reach 25 feet [7.6 metres] tall. The sources give no separate height range for garden plants. A crooked trunk holds a broad crown of fine branches. The crown spreads outward, but the sources give no width. The plant has no leaves for much of the year. This leaves its trunk and branch pattern in view. The fine branches still shape its outline when leaves are gone.

Young bark is smooth and yellow-green. With age, it turns light brown and grows somewhat scaly. The twigs are also smooth and yellow-green. They range from thin to fairly stout. Each short twig ends in a sharp point. Leaves grow in turns along the stems, not in pairs. They last only a short time. Each leaf is bipinnately compound, with two main parts. These look like a pair of pinnate leaves. Each part is about half an inch long. The leaves are green, like the plant's young growth.

Bright yellow flowers form loose groups in spring and early summer. Each flower has five lobes and spans about half an inch. The fruit is a cylindrical legume, a tube-shaped pod. It is 2–4 inches long and bulges around each seed. Both ends taper to sharp points. The pods turn light brown as they ripen in summer. They stay on the tree once ripe. Their swollen shape contrasts with the fine branches and small leaves.

The sources describe the dry habitat where this plant grows. They give no detailed guide to growing it. They list no hardiness zone or measured spread in gardens. They give no facts on pests, diseases, or landscape uses. Nor do they discuss which parts people can eat. They do not address toxicity. These records thus do not show whether any part is safe to eat.