Heliotropium

Heliotropium /ˌhiːliəˈtroʊpiəm, -lioʊ-/[3] is a genus of flowering plants in the borage family, Boraginaceae. There are around 325 species in this almost cosmopolitan genus,[4] which are commonly known as heliotropes (sg. /ˈhiːli.ətroʊp/). It is highly toxic for dogs and cats.

Heliotropium
Heliotropium arborescens
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Boraginales
Family: Boraginaceae
Subfamily: Heliotropioideae
Genus: Heliotropium
L.
Type species
Heliotropium europaeum
L. [1]
Species

250-300, see text

Synonyms

Beruniella Zakirov & Nabiev
Bourjotia Pomel
Bucanion Steven
Cochranea Miers
Meladendron Molina
Parabouchetia Baill.
Valentina Speg.[2]

Etymology

The name "heliotrope" derives from the old idea that the inflorescences of these plants turned their rows of flowers to the sun.[5] Ἥλιος (helios) is Greek for "sun", τρέπειν (trepein) means "to turn". The Middle English name "turnsole" has the same meaning.

A Classical myth, told in Ovid's Metamorphoses, imagines that the water nymph Clytie, in love with the sun god Helios, was betrayed by him. Wasting away, she transformed into the heliotrope, whose flowers supposedly always face the sun.

Ecology and human use
Grey leaf heliotrope Heliotropium ovalifolium at Pocharam lake, Andhra Pradesh, India.

Several heliotropes are popular garden plants, most notably garden heliotrope (H. arborescens). Some species are weeds, and many are hepatotoxic if eaten in large quantities due to abundant pyrrolizidine alkaloids. There have been cases of canine death due to over-ingestion of this toxic plant.[6][7] Some danaine butterflies, such as male queen butterflies, visit these plants, being attracted to their pyrrolizidine alkaloids.[8] Though it is not palatable and most animals will completely ignore it, there have been cases of horses, swine and cattle being poisoned due to contamination of hay.[9]

Caterpillars of the grass jewel (Freyeria trochylus), a gossamer-winged butterfly, feed on H. strigosum.

The sap of heliotrope flowers, namely of European heliotrope (H. europaeum), was used as a food coloring in Middle Ages and Early Modern French cuisine.

One of the most famous ragtime piano melodies is "Heliotrope Bouquet", composed in 1907 by Louis Chauvin (the first two strains) and Scott Joplin (the last two strains).

Garden heliotrope is grown in Southern Europe as an ingredient for perfume.[10]

The purplish facial rash of dermatomyositis is called "heliotrope rash" because it resembles E. arborescens.[11]

Taxonomy

Taxonomic revision supported through molecular phylogenetics led to the recognition of Euploca as genus separate from Heliotropium.[12][4] In contrast, the genus Tournefortia was included in Heliotropium in a 2016 revision.[4]

Within Heliotropium, there are four major clades:[4]

  • Heliotropium sect. Heliothamnus I.M.Johnst.
  • Old World Heliotropium clade
  • Heliotropium sect. Cochranea (Miers) Post & Kuntze
  • Tournefortia clade, comprising Tournefortia sect. Tournefortia and all remaining New World Heliotropium species

Selected species
Heliotropium anomalum var. argenteum
European heliotrope (Heliotropium europaeum)
Indian turnsole (Heliotropium indicum) inflorescence
Heliotropium procumbens habitus
Heliotropium strigosum in Keesara, Ranga Reddy district, Andhra Pradesh, India.

Formerly included here

See also

References
  1. "Heliotropium L". TROPICOS. Missouri Botanical Garden. Retrieved 2010-01-12.
  2. "Genus: Heliotropium L". Germplasm Resources Information Network. United States Department of Agriculture. 2006-04-02. Archived from the original on 2009-08-27. Retrieved 2010-01-12.
  3. Sunset Western Garden Book, 1995:606–607
  4. Luebert, F.; Cecchi, L.; Frohlich, M.W.; et al. (2016). "Familial classification of the Boraginales". Taxon. 65 (3): 502–522. doi:10.12705/653.5. ISSN 0040-0262. Retrieved 16 June 2018.
  5. Chittenden, Fred J. Ed., Royal Horticultural Society Dictionary of Gardening, Oxford 1951
  6. https://web.archive.org/web/20180217091105/http://www.limerickvet.com/news-info/pet-news/in-remembrance-of-goldie/
  7. Kakar, Faizullah et al. “An outbreak of hepatic veno-occlusive disease in Western afghanistan associated with exposure to wheat flour contaminated with pyrrolizidine alkaloids.” Journal of toxicology vol. 2010 (2010): 313280. doi:10.1155/2010/313280
  8. Male sex pheromone of a giant danaine butterfly, Idea leuconoe
  9. Witherill, Richard. "Heliotrope". PAWS Dog Daycare. Retrieved 27 January 2014.
  10. Floridata: Heliotropium arborsecens
  11. http://www.dermnetnz.org/immune/dermatomyositis.html
  12. Hilger, H.H.; Diane, N. (2003). "A systematic analysis of Heliotropiaceae (Boraginales) based on trnL and ITS1 sequence data". Botanische Jahrbücher. 125 (1): 19–51. doi:10.1127/0006-8152/2003/0125-0019. ISSN 0006-8152.
  13. "GRIN Species Records of Heliotropium". Germplasm Resources Information Network. United States Department of Agriculture. Archived from the original on 2012-12-11. Retrieved 2010-09-17.
  • Everitt, J.H.; Lonard, R.L.; Little, C.R. (2007). Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press. ISBN 978-0-89672-614-7.
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