Begonia grandis, white-flowered form
Many gardeners are familiar with Begonia grandis (a.k.a. B. discolor, B. evansiana, B. sinensis), a tuberous species from China commonly known as the "hardy begonia". The name is well-earned: this truly is the hardiest species in a huge but mostly tropical and subtropical genus, going dormant in the winter and able to survive freezing temperatures into zone 6. But for a very long time, the most exciting news about hardy begonias was that they came in white as well as pink. In a genus with so many flashy plants, neither the foliage nor the flowers of B. grandis are terribly exciting. The leaves are handsome enough, and the pink or white flowers are nice coming so late in the season... and darn it, it's a hardy begonia. But hardiness is mostly what it has going for it, and is offset by the thing being downright weedy. It produces little aerial bulbils that act like seeds, dropping all over to produce a steadily-growing colony that will eventually crowd out smaller and slower-growing plants.
