Tradescantia

Tradescantia /ˌtrædɨˈskæntiə/,^[4] the Spiderworts, is a genus of 75 species of perennial plants in the family Commelinaceae, native to the New World from southern Canada south to northern Argentina including the West Indies. Some species have become naturalized in various regions in Europe, Asia, Africa, Australia and assorted oceanic islands.^[3]

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. A number of the species flower in the morning and when the sun shines on the flowers in the afternoon they close, but can remain open on cloudy days until evening.

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.

Description

The leaves are long, thin and bladelike to lanceolate, from 3–45 cm long. The flowers can be white, pink, or purple, but are most commonly bright blue, with three petals and six yellow anthers. The sap is mucilaginous and clear.

Taxonomy

Subdivision

In the 1980s David Hunt divided the genus into 8^[5] (later 12)^[6] sections, with the nominate section (Tradescantia) further subdivided into a further four series, this superseded an earlier system by Clarke (1881).^[7] Hunt originally recognised 60 species of which over half (32) he placed in section Tradescantia. Hunt's original speciation is given here, as further circumscribed by Burns et al. (2011).^[8] Enlarging the sections from eight to twelve added six further species (total 68). Within section Tradescantia he distinguished the American species (series Virginianae) from the three Mexican series (Tuberosae, Sillamontanae, Orchidophyllae). 'Type' 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).
Note 1: The place of T. schippii is uncertain. Hunt indicats it is included in section Zebrina, but Burns considers the section monotypic
Note 2: T. blossfeldiana as used by Hunt and Burns is now considered a synonym for T. cerinthoides. Hunt originally listed these as separate species. Hunt also listed T. potosina and T. nuevoleonensis as separate species, but the latter is now the accepted name, while T. subramosa and T. subtilis are now considered synonyms for T. maysillesii rather than separate species.^[9]

Section Austrotradescantia (3)(7) D.R.Hunt. 5 species (Brazil, Uruguay, N Argentina) Tradescantia anagallidea Seub. Tradescantia umbraculifera Hand.-Mazz. Tradescantia cerinthoides Kunth syn. T blossfeldiana Tradescantia crassula Link & Otto – Succulent Spiderwort Tradescantia fluminensis Vell. – Small-leaf Spiderwort Type Section Campelia (1) (Rich.) D. R. Hunt 1 species (Tropical America) Tradescantia zanonia (L.) Sw. – Cojite Blanco Type Section Coholomia (2)(6) D.R.Hunt 1 species (Guatemala, El Salvador, S Mexico) Tradescantia guatemalensis C. B. Clarke ex Donn.Sm. Type Section Corinna (2) D.R.Hunt 1 species (S Mexico, Guatemala, Nicaragua and Costa Rica) Tradescantia soconuscana Matuda Type Section Cymbispatha (1)(5) (Pichon) D.R.Hunt 9 species (Mexico to Bolivia and Brazil) Tradescantia commelinoides Schult.f. Type Tradescantia coscomatepecana Matuda Tradescantia cymbispatha C.B.Clarke Tradescantia deficiens Brandegee Tradescantia gracillima Standl. Tradescantia plusiantha Standl. Tradescantia standleyi Steyermark Tradescantia tonalamonticola Matuda Tradescantia venezuelensis Steyermark Section Mandonia (7)(11) D.R.Hunt 7 species (Mexico: Durango) Tradescantia ambigua Mart. Type Tradescantia burchii D.R.Hunt Tradescantia crassifolia Cav. – Leatherleaf Spiderwort Tradescantia llamasii Matuda Tradescantia peninsularis Brandegee Tradescantia tepoxtlana Matuda Tradescantia velutina Kunth & Bouché Section Parasetcreasea (8)(12) D.R.Hunt 1 species (Mexico: Chihuahua to Oaxaca) Tradescantia andrieuxii C.B.Clarke Type Section Rhoeo (4) (Hance) D.R.Hunt 1 species (Mexico (Yucatán), Belize) Tradescantia spathacea Sw. – Boatlily, Oyster Plant Section Separotheca (6)(10) (Waterfall) D.R.Hunt 1 species (Mexico: Durango) Tradescantia pygmaea D.R.Hunt Type

Section Setcreasea (5)(9) (K.Schum. & Sydow) D.R.Hunt 5 species (U.S.A.: Texas; Mexico: Chihuahua to Veracruz) Tradescantia brevifolia (Torr.) Rose. – Trans-Pecos Spiderwort Type Tradescantia buckleyi (I.M.Johnst.) D.R.Hunt – Buckley's Spiderwort Tradescantia hirta D.R.Hunt Tradescantia leiandra Torr. – Canyon Spiderwort Tradescantia pallida (Rose) D.R.Hunt – Purple Queen Section Tradescantia (4)(8) L. 32 species Series Virginianae (I) D.R.Hunt (18 species) (U.S.A.) Tradescantia bracteata Small – Bracted Spiderwort Tradescantia canaliculata Raf. Tradescantia edwardsiana Tharp – Plateau Spiderwort Tradescantia ernestiana Anderson & Woodson – Ernest's Spiderwort Tradescantia gigantea Rose – Giant Spiderwort Tradescantia hirsuticaulis Small – Hairystem Spiderwort Tradescantia hirsutiflora Bush – Hairyflower Spiderwort Tradescantia humilis Rose – Texas Spiderwort Tradescantia longipes E.S.Anderson & Woodson – Wild Crocus Tradescantia occidentalis (Britton) Smyth – Prairie Spiderwort Tradescantia ohiensis Raf. – Ohio Spiderwort Tradescantia ozarkana E.S.Anderson & Woodson – Ozark Spiderwort Tradescantia paludosa E.S.Anderson & Woodson – Confederate Spiderwort Tradescantia reverchonii Bush – Reverchon's Spiderwort Tradescantia roseolens Small – Longleaf Spiderwort Tradescantia subacaulis Bush – Stemless Spiderwort Tradescantia subaspera Ker Gawl. – Zigzag Spiderwort Tradescantia tharpii E.S.Anderson & Woodson – Tharp's Spiderwort Tradescantia virginiana L. – Virginia Spiderwort Type Series Sillamontanae (II) D.R.Hunt (2 species) (NE Central Mexico) Tradescantia rozynskii Matuda Tradescantia sillamontana Matuda Type Series Tuberosae (III) D.R.Hunt (10 species) (U.S.A.: Texas; Mexico: Chihuahua to Puebla) Tradescantia cirrifera Mart. Tradescantia maysillesii Matuda syn. T. subramosa, T. subtilis Tradescantia monosperma Brandegee Tradescantia nuevoleonensis Matuda syn. T. potosina Tradescantia pinetorum Greene – Pinewoods Spiderwort Type Tradescantia wrightii Rose & Bush – Wright's Spiderwort Series Orchidophyllae (IV) D.R.Hunt (2 species) (Mexico: Colima to Guerrero) Tradescantia mirandae Matuda Tradescantia orchidophylla Rose & Hemsl. ex Hemsl. Type Section Zebrina (3) (Schnizlein) D.R.Hunt. 1 species (Mexico to Venezuela) (*Tradescantia schippii D.R.Hunt.) Tradescantia zebrina Heynh. ex Bosse – Inchplant Spiderwort Type Incertae sedis Tradescantia pedicellata Celarier – Edwards Plateau Spiderwort[5][6][10][11]

Nothospecies

• Tradescantia × andersoniana W.Ludw. & Rohweder ^[12][13] Phylogenetically T. x andersoniana is situated within series Virginianae, as follows ( T. ohiensis × ( T. subaspera Ker Gawl. × T. virginiana L.)).^[8]

Formerly placed here

• Callisia navicularis (Ortgies) D.R.Hunt (as T. navicularis Ortgies)
• Callisia warszewicziana (Kunth & C.D.Bouché) D.R.Hunt (as T. warszewicziana Kunth & C.D.Bouché)
• Gibasis geniculata (Jacq.) Rohweder (as T. geniculata Jacq.)
• Gibasis karwinskyana (Schult. & Schult.f.) Rohweder (as T. karwinskyana Schult. & Schult.f.)
• Gibasis pellucida (M.Martens & Galeotti) D.R.Hunt (as T. pellucida M.Martens & Galeotti)
• Siderasis fuscata (Lodd. et al.) H.E.Moore (as T. fuscata Lodd. et al.)
• Tinantia anomala (Torr.) C.B.Clarke (as T. anomala Torr.)
• Tripogandra diuretica (Mart.) Handlos (as T. diuretica Mart.)^[11]

Species

By 1998 Fadden listed 70 species.,^[14] while currently The Plant List accepts 75.^[15]

Etymology

The name of the genus honours the English naturalists John Tradescant the Elder (ca. 1570s – 1638) and John Tradescant the Younger (1608–1662).^[16]

Distribution and habitat

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.

Conservation

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.

Cultivation

Though sometimes considered 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. A common cultivar group is derived from the naturally occurring interspecific hybrid (nothospecies) Tradescantia × andersoniana also referred to as 'Andersoniana Group'.^[17] An example is 'Karminglut' ('Carmine Glow').^[18]

Toxicity

Some members of the genus Tradescantia may cause allergic reactions in pets (especially cats and dogs), characterised by red, itchy skin. Notable culprits include T. albiflora (Scurvy Weed); T. spathacea (Moses In The Cradle); and T. pallida (Purple Heart).

Uses

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.^[19]

Radiation induced chiasma

A chiasma (pl. chiasmata) is a cytologically visible interchange at corresponding points between homologous chromosomes. It is the basis for crossover recombination during meiosis. The effect on chiasma frequency of the irradiation of different premeiotic and early meiotic stages was investigated in Tradescantia paludosa.^[20] Chiasma frequency was found to increase following irradiation of the late zygotene early pachytene stages of meiosis. This finding may reflect increased homologous recombinational DNA repair in response to increased radiation-induced DNA damage.^[21]

References

Bibliography

• Edgar Anderson and Karl Sax. A Cytological Monograph of the American Species of Tradescantia. Botanical Gazette Vol. 97, No. 3 (Mar., 1936), pp. 433-476. Article Stable URL: http://www.jstor.org/stable/2471708

Gallery

• 

  Front view of leaves of Tradescantia pallida cv. "Purple Heart".

• 

  Back view of leaves of Tradescantia pallida cv. "Purple Heart".

• 

  Front view of leaves of Tradescantia zebrina cv. "Tricolor".

• 

  Back view of leaves of Tradescantia zebrina cv. "Tricolor".

• 

  A budding Tradescantia flower

• 

  Tradescantia cv. "Red Grape".

External links

• The Plant List
• World Checklist of Selected Plant Families
• Flora of North America: Tradescantia (includes species in USA and Canada only)
• PlantSystematics: Tradescantia
• Western Spiderwort endangered in Canada

Wikisource has the text of the 1920 Encyclopedia Americana article Spiderwort.

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