Tradescantia

Tradescantia /ˌtrædɪˈskæntiə/ is a genus of 75 species of herbaceous perennial wildflowers in the family Commelinaceae, native to the New World from southern Canada to northern Argentina, including the West Indies. Members of the genus are known by the common names spiderwort or Indian paint. They were introduced into Europe as ornamental plants in the 17th century and are now grown as such in many parts of the world. Subsequently, some species have become naturalized in various regions of Europe, Asia, Africa, and Australia, as well as on some oceanic islands. Tradescantia are weakly-upright to scrambling plants, growing 30–60 cm tall (0.98–1.97 ft), and are commonly found individually or in clumps in wooded areas and open fields. A number of species have flowers that unfold in the morning and close when the sun shines on the flowers in the afternoon but can remain open on cloudy days until evening. Three species known colloquially as 'Wandering Jew', one native to eastern Mexico, also belong to the genus Tradescantia. Other names used for various species include spider-lily, cradle-lily, oyster-plant and flowering inch plant. The genus is of interest to cytogenetics because of evolutionary changes in the structure and number of their chromosomes. In addition to their use as ornamentals, Tradescantia is of economic importance because a number of species have become pests to cultivated crops. They have also been used as bioindicators for the detection of environmental mutagens. Tradescantia are herbaceous perennials and include both climbing and trailing species, reaching 30–60 centimetres (0.98–1.97 ft) in height. The leaves are long, thin and blade-like to lanceolate, from 3–45 cm long (1.2–17.7 in). The flowers can be white, pink, or purple, but are most commonly bright blue, with three petals and six yellow anthers (or rarely, four petals and eight yellow anthers). The sap is mucilaginous and clear. Phylogenetic studies suggest that Tradescantia can be subdivided into as many as twenty distinct sections, as given here and further circumscribed by Burns et al. (2011). Enlarging the sections from eight to twelve added six further species for a total of 68. Within section Tradescantia, he distinguished the American species (series Virginianae) from the three Mexican series (Tuberosae, Sillamontanae, and Orchidophyllae). 'Type' as listed here indicates species typica. Numbering of sections refers to Hunt's original (1980) system as a cross check to his index. The renumbered sections from 1986 are given in italics, e.g. (1)(5). By 1998, Fadden listed 70 species, while currently The Plant List accepts 75. The name of the genus by Carl Linnaeus honours the English naturalists and explorers John Tradescant the Elder (c. 1570s – 1638) and John Tradescant the Younger (1608–1662), who introduced many new plants to English gardens. Tradescant the Younger mounted three expeditions to the New World colony of Virginia. From there the type species, Tradescantia virginiana, was brought to England in 1629.