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Tradescantia pallida
Tradescantia pallida is a species of spiderwort native to the Gulf Coast region of eastern Mexico. It is a perennial herbaceous species with a trailing habit. The cultivar T. pallida 'Purpurea', commonly called purple heart or purple queen, is widely grown as a houseplant, outdoor container plant, or a garden groundcover. The species has been proven useful in indicating and removing air and soil pollutants and has also been used in food technology. TaxonomyT. pallida is a species of spiderwort in the family Commelinaceae.[2] The type specimen was collected by Edward Palmer, one of the main US plant collectors of his time, in the Mexican state of Tamaulipas (possibly near Ciudad Victoria[3]) in 1907.[4] The species was described by Joseph Nelson Rose in 1911. He placed it in the genus Setcreasea. In 1975 David Hunt transferred the species to the genus Tradescantia.[2] Hunt also treated Setcreasea purpurea as a cultivar of S. pallida.[3] The latter names are still often used to refer to T. pallida.[2] The specific epithet pallida means "pale", referring to the original color of the leaves.[4] The plant is known by several common names, including purple heart (probably in reference to the eponymous military medal[4]) and purple wandering jew.[2] DescriptionT. pallida is perennial and herbaceous. It has a rambling habit, with plants reaching about a 1 ft (30 cm) in height but spreading considerably wider:[2] the stems may trail to 18 in (46 cm) or more.[5] Wild specimens are gray-green-purplish with a washed out look.[4]  The fleshy, hairy leaves are up to 7 in (180 mm) long,[2] narrow-oblong, and v-shaped.[5] and form a sheath around fleshy stems, which break off easily. On the ends of the stems the plants produce relatively inconspicuous flowers. The flowers are three-petaled as is typical for the Tradescantia genus. The flowering is most abundant from midsummer through fall and sporadic at other times of the year.[2] The flowers are open only in the morning.[4] The plants are evergreen,[4] but in colder areas die back to the ground in winter and resprout from the roots in spring.[2] Distribution and habitatT. pallida is found along the coast of the Gulf of Mexico. Its native range extends from Tamaulipas to Yucatan.[4] The species has been collected in a tropical deciduous forest, among roadside limestone rocks, and on limestone outcrops.[3] Uses T. pallida is grown as an ornamental plant for its attractive foliage.[2] Only the cultivar 'Purpurea', featuring purple-violet leaves and stems,[5] is commercially grown.[4] 'Purpurea' is sometimes sold under the name 'Purple Heart',[5] and has gained the Royal Horticultural Society's Award of Garden Merit.[6] T. pallida is a popular groundcover plant in tropical and semi-tropical areas. In temperate climates it has traditionally been used as a houseplant but is increasingly being planted outdoors in containers or as a groundcover. It is also suitable for hanging baskets, border fronts, and rock gardens.[5] The plant is hardy down to USDA zone 7.[2] It may be grown in the shade but the most intense purple color is achieved in full sun.[2][4][5] The plant is remarkable for easily tolerating both drought[2][4][5] and frequent watering.[2] It is generally not affected by pests or diseases; however, slugs and caterpillars may attack young shoots of outdoor specimens, while houseplants should be monitored for aphids and scale.[5] T. pallida has been proven useful for phytoremediation, biomonitoring, and genotoxicity assessment of environmental pollutants, especially heavy metals and metalloids from coal power plants.[7] As a houseplant, T. pallida has been judged exceptionally effective at improving indoor air quality by filtering out volatile organic compounds, a class of common pollutants and respiratory irritants.[8] Because the plant contains anthocyanins, T. pallida leaves have been used as food colorants[9][10] and food preservatives.[10] References
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