It is gratifying to see renewed interest in this old fashioned flower. Naturally occurring varieties of some of the nearly three dozen species of Iochroma were popular decades ago. Some might actually be naturally occurring hybrids that have yet to be identified. Many modern cultivars (cultivated varieties) were intentionally bred or hybridized for more compact growth and profuse bloom.
Old fashioned varieties of Iochroma are occasionally seen as large rampant shrubbery or even small trees in old established landscapes. Modern cultivars are more compact and manageable. For the fullest and most vigorous growth in summer, they can be pruned aggressively as winter ends, but should otherwise be pruned only for shape and confinement. They should never be shorn.
If Iochroma resembles angel's trumpet, it is because they are related. The foliage is very similar, although the leaves are smaller. The narrowly tubular flowers are much smaller and clustered. The hummingbirds who like them so much do not even need to reach their beaks all the way in. Bloom is purple, blue, red, pink or maybe white or yellow. Iochroma happens to do well in partial shade.