Charles Day is Wave Hill’s Ruth Rea Howell Horticultural Interpreter.
This tender perennial—that is, a plant that is capable of living more than one year in a warmer climate but is killed by our winters here—comes from southern Africa. It is related to the milkweeds (Asclepias spp.), and can serve as a food source for the caterpillars of the monarch butterfly.Growing from seed sown in spring, it makes a statuesque plant of seven feet or more by late summer. The blooms are very similar in shape to the native milkweeds but are white, rather than orange or pink, and the seed cases are large, balloon-like spheres.
Florists use these in arrangements and you may see cuttings available for sale in some stores. Severe frosts will kill the entire plant. But a few degrees of freezing conditions does not harm it much, and there is a good chance that the examples in the Flower Garden will stand proud for some weeks yet.