Plant Evaluation Notes ISSUE 34, 2010 A Comparative Study of Tradescantia Cultivars

Despite the fact that Tradescantia is in the predominantly tropical dayflower family (Commelinaceae), spiderworts are indige-nous to most of the continental United States, with species variously adapted to full sun, deep shade, high or low tempera-tures, and xeric habitats. Tradescantia virginiana, Virginia spiderwort, has a long ethnobotanical and horticultural history. Native Americans used Virginia spiderwort to treat a variety of ailments from stom-achaches to cancer, as well as for food. It was among the first North American plants to be introduced to European gardens in the early 1600s. Interestingly, some spiderworts are natural Geiger counters of a sort. The fuzzy filament hairs in the flower change from blue to pink when exposed to low levels of nuclear radiation. Many temperate spiderworts are useful garden plants, while tropical species such as wandering Jew (Tradescantia zebrina) and Moses-in-a-boat (T. spathacea) are valuable houseplants. Most of the commer-cially available and commonly grown hardy garden spiderworts are of complex hybrid origin, derived from crosses between T. virginiana, T. ohiensis (bluejacket), and T. subaspera (zigzag spiderwort), which occur naturally in overlapping ranges in the eastern United States. Selections of these hybrids are often lumped erroneously under the invalidly named T. andersoniana, but are more appropriately designated Andersoniana Group. A kaleidoscopic palette of colors—sump-tuous blues, rich purples, lush violets, vibrant pinks, and brilliant whites—mark the ephemeral blossoms of spiderworts. Flowers last for one day only; hence, the origin of the common name dayflower. Flowers are actually open for less than a day, since the delicate petals curl up by afternoon as the heat of the day rises. Flowers may remain open longer on cool or cloudy days or when grown in shade. Tradescantia 'Zwanenburg Blue' Ri ch a