Calliandra houstoniana aka Stickpea

Calliandra houstoniana is a shrub or small tree in the pea family, Fabaceae. Its native range runs from Mexico to Nicaragua, according to Kew. Useful Tropical Plants gives a narrower range, from southern Mexico to Honduras. It is a woody plant with a fine, light form. People grow it for its flowers, though ornamental use is occasional. It also grows wild across parts of its native range.

Useful Tropical Plants lists a height of about 8 feet [2.5 metres]. Its fuller account gives a broader range of 3–20 feet [1–6 metres]. These figures suggest that plants can vary in size. The source does not give a separate cultivated height range. It describes the flowers as a feature but gives no bloom season. The supplied species accounts do not describe leaf shape, bark texture, or fruit. The RHS leaf and flower details refer to the genus, not this species.

In the wild, this plant grows on open slopes and among scrub. It occurs on both damp and dry ground. It also grows on cliff faces and sometimes in pine-oak woods. Records place it as high as 7,218 feet [2,200 metres]. Kew places it in a tropical climate with a dry season. These habitat records describe its wild settings, rather than a tested garden watering schedule.

For cultivation, Useful Tropical Plants calls for sun and soil that drains well. It reports that the species grows in tropical and subtropical regions. The supplied accounts give no frost limit or hardiness zone. Bacteria form nodules on its roots and capture nitrogen from the air. The plant uses some of this nitrogen. Plants growing close by may also gain from it. The source lists seed as a means of propagation. It gives no species-specific pest or disease details.

The bark has a history of medicinal use and export to Europe. Traders sold it as Pambotana bark, a substitute for quinine. Records also describe chewing the bark to firm the gums. These reports document past use, not proof of safety or benefit. The bark contains an alkaloid that can stop the heart and cause death. Useful Tropical Plants records no known food uses. Its toxic bark makes the distinction between historical use and safe use important.