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Sonchus oleraceus L.

Protologue
Sp. pl. 2: 794 (1753).
Family
Asteraceae (Compositae)
Chromosome number
2n = 32
Vernacular names
Smooth sow thistle, annual sow thistle, common sowthistle, milk thistle (En). Laiteron potager, laiteron maraîcher, laiteron commun, lastron (Fr). Serralha branca, serralha macia, leita ruga (Po).
Origin and geographic distribution
Sonchus oleraceus is native to Eurasia and northern Africa. It is currently a cosmopolitan weed.
Uses
Throughout Africa, the primary use of Sonchus oleraceus is as a cooked leafy vegetable, but it is also eaten raw. The tender leaves are eaten as a salad and some people also eat the juicy root. In Uganda the Langi people first dry the leaves and later boil and mash them to be added to beans or made into a sauce that is eaten with a staple food. In Tanzania and Madagascar the roots are used as a purgative, and in Tanzania as an abortifacient and vermifuge. The use of leaf sap to treat earache (Tanzania, China, New Zealand) and deafness (western Europe) is probably effective in cases where excessive amounts of earwax are the underlying cause of the problem. The leaves are said to clear infections, are used as a sedative, stomachic, diuretic and to treat liver diseases, including hepatitis. Further medicinal uses are the treatment of eye problems (Burundi), gastritis, salmonella infection (Madagascar), kwashiorkor and anaemia (Burundi, Sudan, Uganda). In China the latex is used as a cure for opium addiction and to treat warts and cancer. For Burundi several veterinary applications are recorded (e.g. to treat diarrhoea, haematuria, vaginal prolapse). Sow-thistle is a favourite food for rabbits and poultry and it is also used as fodder for cattle. The white latex is suspected of being mildly poisonous and cases of poisoning of lambs (Somalia) and horses (Australia) have been attributed to Sonchus oleraceus.
Properties
The leaves taste mild to quite bitter. Leaves contain per 100 g edible portion: water 87 g, energy 110 kJ (26 kcal), protein 3.2 g, carbohydrate 1.8 g, fibre 3.3 g, Ca 32 mg, Mg 76 mg, P 58 mg, Fe 3.8 mg, Zn 0.8 mg, carotene 16 mg, ascorbic acid 78 mg (Guil-Guerrero, J.L., Giménez-Giménez, A., Rodríguez-García, I. & Torija-Isasa, M.E., 1998).
Callus cultures of Sonchus oleraceus showed broad spectrum antibacterial activity. The aqueous extract demonstrated acaricidal activity against the two-spotted spider mite, Tetranychus urticae. Sesquiterpene lactones, especially of the eudesmanolide type, have been isolated from Sonchus species.
Botany
Annual or biennial herb up to 1.4 m tall; stem ridged, simple or branched. Leaves alternate, simple; blade lanceolate or oblanceolate, 4–30 cm × 1–9(–17) cm, deeply pinnately lobed with few, reflexed lobes, coarsely toothed, base amplexicaul with pointed auricles, but basal leaves attenuate at base, apex rounded or acute; distal leaves smaller and less lobed. Inflorescence a stalked head, few to many together arranged in a lax, leafy corymb or panicle; involucre 10–13 mm long. Flowers bisexual, ligulate, yellow; corolla tube 6–7.5 mm long, ligule c. 6 mm long; stamens 5, anthers united into a tube around the style; ovary inferior, 1-celled, style 2-branched. Fruit a slightly flattened, ribbed, rugose achene up to 4 mm long, with white pappus 7–8 mm long. Seedling with epigeal germination; hypocotyl 0.5–1 cm long; cotyledons leafy, oblong-elliptical.
Sonchus comprises about 60 species, of which 17 have been recorded in tropical Africa. The many small light seeds of Sonchus oleraceus disperse readily by wind and water. Germination can take place at temperatures ranging from 7°C to over 35°C.
Ecology
Sonchus oleraceus is mainly found in disturbed localities, including farmland, abandoned fields and recently burned fields, up to 2650 m altitude.
Management
In Africa Sonchus oleraceus is collected from the wild and is not cultivated. It is only traded on a small scale at local markets, e.g. in Tanzania. In Indonesia it is cultivated on a small scale, and also in ancient times in Europe. The number of viral diseases it hosts is large (e.g. watermelon mosaic virus (WMV), pepino mosaic virus (PepMV), tomato spotted wilt virus (TSWV) and alfalfa mosaic virus (AMV)). Sonchus oleraceus further is a host for castor whitefly (Trialeurodes ricini), Bemisia whiteflies, cotton bollworm (Helicoverpa armigera) and the nematode Radopholus similis. Sonchus oleraceus is a preferred host for the cotton bollworm.
Genetic resources and breeding
In view of its worldwide distribution and abundance there is no threat of genetic erosion and there have been no attempts to collect and maintain germplasm.
Prospects
Interest from scientists in Sonchus oleraceus will continue to be focused on its role in crop yield reduction and as a host of diseases and pests. Monitoring and control of insect populations with this species as a trap crop offers possibilities. Medicinal and toxic properties require further investigations. As a vegetable it is likely to remain of minor importance.
Major references
• Andersen, R.N., 1968. Germination and establishment of weeds for experimental purposes. Weed Science Society of America handbook. University of Illinois, Urbana, United States. 236 pp.
• Beentje, H.J., 2000. Compositae (part 1). In: Beentje, H.J. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 1–313.
• Guil-Guerrero, J.L., Giménez-Giménez, A., Rodríguez-García, I. & Torija-Isasa, M.E., 1998. Nutritional composition of Sonchus species (S. asper L., S. oleraceus L. and S. tenerrimus L.). Journal of the Science of Food and Agriculture 76: 628–632.
• Herbison-Evans, D. & Crossley, S., 2003. Helicoverpa armigera: Corn ear worm, tomato grub, tobacco budworm, cotton bollworm (Heliothinae, Noctuidae). [Internet] http://www.usyd.edu.au/su/macleay/larvae/noct/armi.html. Accessed September 2003.
• Katende, A.B., Ssegawa, P. & Birnie, A., 1999. Wild food plants and mushrooms of Uganda. Technical Handbook No 19. Regional Land Management Unit/SIDA, Nairobi, Kenya. 490 pp.
Other references
• Baerts, M. & Lehmann, J., 2002. Sonchus oleraceus. [Internet] A few medicinal plants used in traditional veterinary and human medicine in sub-saharan Africa. Laboratoire de Botanique Médicale de Louvain-la-Neuve, Belgium. http://www.fynu.ucl.ac.be/users/j.lehmann/plante_ang/Sonchus_oleraceus.html. Accessed October 2003.
• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, United Kingdom. 960 pp.
• Decary, R., 1946. Plantes et animaux utiles de Madagascar. Annales du Musée Colonial de Marseille, 54e année, 6e série, 4e volume, 1er et dernier fascicule. 234 pp.
• Gu, H., Cao, A. & Walter, G.H., 2003. Host selection and utilisation of Sonchus oleraceus (Asteraceae) by Helicoverpa armigera (Lepidoptera: Noctuidae): a genetic analysis. Annals of Applied Biology 138(3): 293–299.
• Hidajat, E.B., 1993. Sonchus L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 260–262.
• Khafagi-Ishrak, K., 1999. Screening in vitro cultures of some Sinai medicinal plants for their antibiotic activity. Egyptian Journal of Microbiology 34(4): 613–627.
• Leonard, D.B., 2003. Medicine at your feet: plants and food. [Internet] . Accessed September 2003. • Pope, G.V., 1992. Compositae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 6, part 1. Flora Zambesiaca Managing Committee, London, United Kingdom. 264 pp.
• Watt, J.M. & Breyer-Brandwijk, M.G., 1962. The medicinal and poisonous plants of southern and eastern Africa. 2nd Edition. E. and S. Livingstone, London, United Kingdom. 1457 pp.
Sources of illustration
• Hidajat, E.B., 1993. Sonchus L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 260–262.
Author(s)
R.R. Schippers
De Boeier 7, 3742 GD Baarn, Netherlands


Editors
G.J.H. Grubben
Prins Hendriklaan 24, 1401 AT Bussum, Netherlands
O.A. Denton
National Horticultural Research Institute, P.M.B. 5432, Idi-Ishin, Ibadan, Nigeria
Associate Editors
C.-M. Messiaen
Bat. B 3, Résidence La Guirlande, 75, rue de Fontcarrade, 34070 Montpellier, France
R.R. Schippers
De Boeier 7, 3742 GD Baarn, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Illustrator
PROSEA
PROSEA Network Office, Herbarium Bogoriense, P.O. Box 234, Bogor 16122, Indonesia

Correct citation of this article:
Schippers, R.R., 2004. Sonchus oleraceus L. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.
plant habit.
Source: PROSEA