CAM Photosynthesis in Bulnesia retama (Zygophyllaceae), a non-succulent desert shrub from South America.

Bulnesia retama is a weak to modest C3+CAM plant. This is the first report of CAM in the Zygophyllaceae and the first showing non-succulent, xerophytic shrubs use CAM. CAM alone in B. retama was too limited to explain less negative δ13C in field-collected plants but combined with effects of low stomatal and mesophyll conductance could raise δ13C to observed values between -16‰ and -19‰. Modest CAM activity, particularly during severe drought, could enable B. retama to persist in arid habitats of South America.