Impatiens

The "busy lizzy" — by Missouri Botanical Garden's account "the most popular annual bedding plant in the U.S. today," prized for non-stop flowering in shade where most annuals sulk. A succulent-stemmed tender perennial from East Africa (Tanzania, Mozambique), it is grown as an annual everywhere but USDA zones 10-11, mounding 6-24 inches tall and covering itself with showy, slender-spurred, five-petaled flowers in pink, rose, red, lilac, purple, orange, white, and bicolors from June to frost. Worth knowing before you plant a whole bed: the species is susceptible to impatiens downy mildew (Plasmopara obducens), which can collapse a planting.

A tender perennial from New Guinea grown almost everywhere in North America as a warm-season annual, prized for non-stop bright bloom in part shade — and, unlike common impatiens, in considerably more sun. It mounds 6-24 inches tall and 18-36 inches wide, carrying large, flat, five-petaled flowers in coral, salmon, pink, red, orange, lavender, and white above bold, often bronze-tinted dark foliage. Its real selling point is honest and practical: Impatiens hawkeri is resistant to impatiens downy mildew (Plasmopara obducens), the disease that collapsed plantings of Impatiens walleriana, making it the dependable shade-to-part-sun bedding plant where the common species can no longer be trusted.