Shrub native to Mexico and Central America which is widely cultivated for its showy scarlet bracts?

The answer is poinsettia. Poinsettias are native to Mexico and Central America, and are widely cultivated for their showy scarlet bracts, which are often mistaken for flowers. The bracts are actually modified leaves, and the true flowers are small and insignificant, located in the center of the bracts. Poinsettias are popular holiday plants, and are often associated with Christmas.