Few genera contain such multitudes. Begonia stretches across the humid understories of South America, Africa, and Asia, where its ancestors learned to make the most of dappled light and rich forest soils. The asymmetrical leaf, a signature across all 2,100-plus species, is no accident: it is thought to help the plant harvest scattered photons from forest gaps. In the garden, this translates to a genus that genuinely prefers the corners and margins where other flowering plants give up.

The diversity within the genus is staggering. Wax begonias hug the border edge with their relentless small blooms; tuberous types produce flowers large enough to stop conversation; rhizomatous cultivars offer foliage in chocolate, bronze, and silver that outshines almost any flower. Most ask for moist, well-drained soil with plenty of organic matter, a pH between 5.5 and 6.5, and protection from temperatures below 55 degrees F. Given those modest conditions, the genus delivers color, texture, and curiosity in equal measure.