Tradescantia

taxobox
name = Spiderwort


image_caption = Spiderwort ("Tradescantia virginiana")
regnum = Plantae
unranked_divisio = Angiosperms
unranked_classis = Monocots
unranked_ordo = Commelinids
ordo = Commelinales
familia = Commelinaceae
genus = "Tradescantia"
genus_authority = L., 1753
subdivision_ranks = Species
subdivision = About 70, including:
"Tradescantia bracteata"
"Tradescantia brevifolia"
"Tradescantia buckleyi"
"Tradescantia cerinthoides"
"Tradescantia crassifolia"
"Tradescantia crassula"
"Tradescantia edwardsiana"
"Tradescantia ernestiana"
"Tradescantia fluminensis"
"Tradescantia gigantea"
"Tradescantia hirsuticaulis"
"Tradescantia hirsutiflora"
"Tradescantia humilis"
"Tradescantia iridescens"
"Tradescantia leiandra"
"Tradescantia longipes"
"Tradescantia navicularis"
"Tradescantia occidentalis"
"Tradescantia ohiensis"
"Tradescantia ozarkana"
"Tradescantia pallida"
"Tradescantia paludosa"
"Tradescantia pedicellata"
"Tradescantia pinetorum"
"Tradescantia roseolens"
"Tradescantia reverchonii"
"Tradescantia sillamontana"
"Tradescantia spathacea"
"Tradescantia subacaulis"
"Tradescantia subaspera"
"Tradescantia tepoxtlana"
"Tradescantia tharpii"
"Tradescantia virginiana"
"Tradescantia wrightii"
"Tradescantia zanonia"
"Tradescantia zebrina"
synonyms = "Setcreasea" "Zebrina"|

Spiderwort ("Tradescantia") is a genus of an estimated 71 species of perennial plants in the family Commelinaceae, native to the New World from southern Canada south to northern Argentina. They are weakly upright to scrambling plants, growing to 30-60 cm tall, and are commonly found individually or in clumps in wooded areas and fields. The leaves are long, thin and bladelike to lanceolate, from 3-45 cm long. The flowers are white, pink or purple but most commonly bright blue, with three petals and six yellow anthers. The sap is mucilaginous and clear. A number of the species flower in the morning and when the sun shines on the flowers in the afternoon they close up, but the flowers can remain open on cloudy days until evening.

Though sometimes accounted a weed, spiderwort is cultivated for borders and also used in containers. Where it appears as a volunteer, it is often welcomed and allowed to stay.

The first species described, Virginia Spiderwort "T. virginiana", is native to the eastern United States from Maine to Alabama, and Canada in southern Ontario. Virginia Spiderwort was introduced to Europe in 1629, where it is cultivated as a garden flower.

The Western Spiderwort "T. occidentalis" is listed as an endangered species in Canada, where the northernmost populations of the species are found at a few sites in southern Saskatchewan, Manitoba and Alberta; it is however more common further south in the United States south to Texas and Arizona.

The three species of Wandering Jew, one native to eastern Mexico, also belong to the tradescantia genus. Other names used for various species include Spider-lily, Cradle-lily, Oyster-plant and Flowering Inch Plant.

The genus takes its name from John Tradescant the elder, an 17th century English plant collector and nurseryman.

tamen hairs and ionizing radiation

The cells of the stamen hairs of some "Tradescantia" are colored blue, but when exposed to sources of ionizing radiation such as gamma rays, the cells mutate and change color to pink; they are one of the few tissues known to serve as an effective bioassay for ambient radiation levels. [http://www.journalarchive.jst.go.jp/english/jnlabstract_en.php?cdjournal=ggs1921&cdvol=47&noissue=6&startpage=411]

External links

* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=133268 Flora of North America: "Tradescantia"] (includes species in USA and Canada only)
* [http://132.236.163.181/cgi-bin/dol/dol_terminal.pl?genus=Tradescantia PlantSystematics: "Tradescantia"]
* [http://www.se.gov.sk.ca/ecosystem/speciesatrisk/westernspiderwort.htm Western Spiderwort endangered in Canada]

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