Justicia carnea

Justicia carnea (juss-TISH-ee-uh KAR-nee-uh) is also widely known as Jacobinia, Flamingo Flower, and Brazilian Plume. This amazing plant will grow in sun or shade, and blooms every month of the year in the warmer parts of its range. The natural height is three to four feet, and pruning is not usually needed.
Buds form at the tip of new growth, and once the pink starts to show, it's only a few days until full bloom. Each flowering head lasts a week or so, and more continue to form whenever the plant is in active growth.

Justicia carnea is native to South America. It is recommended for USDA Zones 8 to 11. In Zone 8 they will freeze to the ground each winter, but come back in the spring. Most references indicate this plant prefers shade, but if adequately watered, the foliage gets firmer and more deeply veined in full sun.

White, red, orange, purple, and yellow color forms exist (mostly hybrids), but pink is the most common.

As an added bonus, hummingbirds are attracted to the flowers.