Malvaviscus arboreus var. mexicanus is a fall and winter-blooming relative of Hibiscus. The bright red flowers are pendulous and last for several days. The petals do not flare back like Hibiscus, but remain swirled around the pistil. This gives the impression that the flowers never open, and hence the common name of Sleeping Hibiscus. It is also sometimes known as Turk's Cap or Lipstick Hibiscus. There is a pale pink color-form that is not as showy.
Malvaviscus arboreus is a large woody shrub growing to eight foot tall by six foot wide. It is native to Mexico and is recommended for USDA Zones 9-12. It flowers best in full sun, but will tolerate light shade. It is drought-tolerant once established.
There are two distinct varieties and many online resources confuse the two. Variety mexicanus is the one pictured and described here, and is the one most commonly grown in Florida. Variety drummondii (most commonly grown in Texas) apparently has broader fuzzy leaves, more erect flowers, red fruits, enjoys moist, part-shade conditions, can become almost vine-like, blooms in summer, and is apparently more cold-hardy. One online nursery is growing them as a perennial in Zone 6B!
It's strange that these two plants are classified as varieties and not separate species, given their completely different habitats and form. If you're shopping for this plant, make sure you know which one you're getting!