Justicia longii

Justicia longii (longflower tube tongue) is an herbaceous perennial subshrub in the acanthus family (Acanthaceae) found in the Arizona Upland of the Sonoran Desert. Each of its white flowers blooms in the evening and lasts only a single night. The next morning the corollas fall, littering the ground with a white carpet. It has a long bloom season from April to October.