Sonchus (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Sonchus L.

Protologue: Sp. pl.: 793 (1753); Gen. pl. ed. 5: 347 (1754).

Family: Compositae

Chromosome number: x= 7, 8, 9; 2n= 18 (Sonchus asper, S. wightianus); 2n= 32 (S. oleraceus); 2n= 54 (S. malaianus)

Major species and synonyms

• Sonchus asper (L.) Hill, Herb. Brit. 1: 47 (1769), synonym: S. cuspidatus Blume (1826).

• Sonchus malaianus Miquel, Fl. Ind. Bat. 2: 113 (1856), synonyms: S. javanicus Jungh. (1845), non Sprengel (1826), S. oreophilus Miquel (1856), S. maritimus L. var. malaianus (Miquel) Hochr. (1934).

• Sonchus oleraceus L., Sp. pl.: 794 (1753), synonym: S. sundaicus Blume (1826).

• Sonchus wightianus DC., Prodr. 7: 187 (1838), synonym: S. arvensis L. sensu mult. auct.

Vernacular names

S. asper:

• Spiny sow thistle (En)
• Laiteron épineux (Fr)
• Indonesia: delgiyu (Javanese), camawak (Sundanese)
• Thailand: phakkat-hom (central), phakkat-hangkai (southern).

S. malaianus:

• Indonesia: kumindelan, blenggi.

S. oleraceus:

• Common sow thistle (En)
• Laiteron commun (Fr)
• Indonesia: tempuh wiyang, delgiyu (Javanese), camawak (Sundanese)
• Philippines: gagatang (Igorot)
• Vietnam: rau diếp dại, nhũ cúc, rau cúc sữa.

S. wightianus:

• Indonesia: tempuyung (Javanese), lempung (Sundanese), jombang
• Philippines: lampaka (Ilocano), lunglung an manema (Ifugao), pisay a otan (Marinduque)
• Vietnam: nhũ cúc dồng.

Origin and geographic distribution

The genus Sonchus is of Old World origin and is widely distributed. S. asper and S. oleraceus are cosmopolitan weeds, occurring from the Arctic zone to the tropics. S. wightianus is of Asian origin and distributed from Afghanistan through South Asia and Indo-China to Taiwan. In Malesia it occurs in the Philippines and Indonesia (Java). S. malaianus is endemic to the Indonesian islands of Sumatra and Java.

Uses

Sonchus species have a long record of being used as leafy vegetables in many parts of the world. The leaves are consumed raw as a salad or cooked as a spinach. They are also a good animal feed. S. asper and S. oleraceus are applied worldwide in folk medicine as stomachic, aperitive and diuretic. S. wightianus is used in Indonesia to treat kidney stones and jaundice.

Production and international trade

For vegetable use, Sonchus leaves are gathered mainly from the wild. However, S. wightianus is planted on a small scale in Java, mainly to produce tablets and tea bags for medicinal use. No statistics are available.

Properties

There is no information on the nutritional value of Sonchus leaves. S. wightianus is reported to contain taraxasterol and inositol. The capacity of leaf extract to dissolve calcium from kidney stones is greatest in S. wightianus and less so in S. oleraceus and S. asper. The 1000-seed weight of S. wightianus has been reported to be 0.4 g.

Description

• Annual or perennial, erect herbs up to 3 m tall, containing a bitter milky juice, with a well-developed branched taproot or rarely a creeping rhizome.
• Stems hollow, cylindrical or slightly angular, glabrous or with glandular hairs near the top.
• Leaves in a rosette or cauline, alternate, usually auricled and clasping, usually divided and with denticulate margins.
• Inflorescence a head, usually numerous and arranged in terminal corymbs, each head with 40-500 bisexual flowers; peduncle 0.2-16 cm long, with 1-12 triangular bracts; involucral bracts numerous, imbricated in 3 rows; corolla ligulate, 1-3 cm long, yellow, with a 4-14 mm long linear ligule, 5-dentate at top; the relative lengths of the corolla tube and the ligule are important for the distinction of the species; anthers 5, forming a staminal tube; style with 2 branches.
• Fruit an achene, usually ellipsoid, 2-6.5 mm × 0.5-1.75 mm, laterally compressed, brown, with 1-4 main ribs on each side, with a 4-14 mm long caducous or persistent pappus.

S. asper.

• Annual, polymorphic, branched herb, up to 120 cm tall.
• Leaves mostly cauline, variable in outline, 5-25 cm × 3-8 cm, entire to pinnatipartite; lobes more or less triangular, with spiny margins.
• Per head 80-300 flowers; involucral bracts ca. 40; corolla tube ca. 6 mm, ligule 4 mm long.
• Achene strongly compressed, 2-3 mm × 1 mm, with 3 ribs on each side and winged, ciliate margins; pappus ca. 3 times as long as the achene, caducous.

S. malaianus.

• Perennial, branched herb, up to 180 cm tall.
• Cauline leaves, narrowly elliptical to rectangular, 8-28 cm × 0.5-3.5 cm, entire, subcoriaceous, margins entire or dentate.
• Per head 100-150 flowers; involucral bracts ca. 35; corolla tube 7-10 mm, ligule 7-8.5 mm long.
• Achene wrinkled, 4-4.5 mm × 1.2 mm, with 1 major and 4 minor ribs on each side; pappus ca. 11 mm long, subpersistent.

S. oleraceus.

• Annual or biennial, branched herb, up to 140 cm tall.
• Cauline leaves, variable in outline, 8-35 cm × 4-17 cm, entire to pinnatipartite; lobes entire, dentate or spiny.
• Per head 80-230 flowers; involucral bracts ca. 30; corolla tube as long as the ligule, 6 mm.
• Achene rough, oblanceolate, 2.5-3.75 mm × 0.75-1 mm, with 2-4 main ribs on each side; pappus about two times as long as the achene, subpersistent.

S. wightianus.

• Perennial, branched herb, up to 140 cm tall, always with a taproot, sometimes rhizomatic as well.
• Rosette and cauline leaves 5-30 cm × 1-6 cm, entire to pinnatipartite; lobes more or less triangular, with dentate to spiny margin; upper leaves short, lanceolate to narrowly triangular.
• Per head 180-300 flowers; involucral bracts ca. 40, densely glandular hairy; corolla tube 7-8 mm, ligule 5-6 mm long.
• Achene wrinkled, 3.5-4.25 mm × 1 mm, with 1 major and 4 minor ribs on each side; pappus ca. 8 mm long, subpersistent.

Other botanical information

S. asper was originally described as a variety of S. oleraceus. Hybrids between these two taxa are sterile (2n= 25), so it seems better to consider them as different species. Forms of S. asper with the flowerheads arranged in umbels, the leaves stiff and very spiny and all in a rosette, and the achenes with pronounced and ciliate ridges, have been classified as ssp. glaucescens (Jordan) Ball.

S. malaianus is probably a hexaploid species with x= 9. Its entire and subcoriaceous leaves are very distinctive. It is more common in Java than Sumatra.

S. oleraceus has very variable leaves, probably due to its supposed amphidiploid origin (S. asper × S. tenerrimus L., 2n= 18 + 14 = 32). The more or less equal length of the tube and the ligule of its corolla is very characteristic for this species (for S. asper that ratio is 2 : 3). The species has often been subdivided into different taxa, based on vegetative characters. Its variability is such, that two identical plants can rarely be found, so that any subdivision seems without practical value.

S. wightianus has often been considered as a synonym of S. arvensis L., the milk thistle of Europe and America, but it is a different species. S. wightianus always has a taproot (S. arvensis is purely rhizomatic) and its fruits are longer, narrower and less wrinkled than those of S. arvensis. S. arvensis does not occur in South-East Asia. Forms of S. wightianus with white-hairy heads without glandular hairs are classified as ssp. wallichianus (DC.) Boulos.

Ecology

The wide distribution of S. asper and S. oleraceus is proof of their great ecological adaptability. Gardens and cultivated terrains in humid to subhumid areas are their normal habitat. S. asper prefers a slightly cooler and more humid environment than S. oleraceus. They have no specific edaphic requirements. S. malaianus has been reported from tropical forests and roadsides at elevations above 1000 m in Sumatra and Java. S. wightianus occurs in humid places such as dikes of paddy fields and irrigation canals up to 3200 m altitude. All 4 species usually flower and fruit year-round.

Agronomy

Propagation is mainly by seed, which is produced abundantly and dispersed readily by wind and water. Fragments of the rhizome of S. wightianus also easily sprout. Sonchus species are rarely cultivated in South-East Asia for vegetable use. Leaves are collected from plants growing in the wild. As a medicinal plant, S. wightianus is sown in a nursery; seedlings are transplanted one month from sowing at distances of 25-50 cm × 25-50 cm. To induce branching, plants are pruned to a height of 10-25 cm. Leaves are hand-picked at regular intervals, starting 2 months after transplanting. They are immediately dried in full sunshine for 2-3 days and stored in airtight containers. A dry leaf yield of 900-1200 kg/ha in 4-6 months has been reported.

Diseases like anthracnose (Gloeosporium spp.) and rust (Puccinia sonchi-arvensis) may decrease the healthy leaf area.

Genetic resources and breeding

To date there has been no systematic germplasm collection or selection and breeding for Sonchus species.

Prospects

Sonchus species are minor vegetable greens. Their medicinal applications may also stimulate their consumption as a vegetable. This applies in particular to S. wightianus. Any breeding work should focus first on reducing the bitterness.

Literature

• Boulos, L., 1973. Révision systématique du genre Sonchus L. s.l. IV. Sous-genre 1. Sonchus [Systematic revision of the genus Sonchus L. s.l. IV. Subgenus 1. Sonchus]. Botaniska Notiser 126: 155-196.
• Kurnia, Sasongko, E., Untari, E. & Sylvia S., 1975. A study on the dissolving capacity of Sonchus spp. and 4 species of keci beling on several calcium stones. Proceedings First Symposium on Medicinal Plant Research, Bogor, Indonesia. pp. 169-175.
• Soediarto, 1973. Guide to the cultivation of jombang (Sonchus arvensis L.). Research Institute for Industrial Crops, Bogor, Indonesia, Circular No 7: 1-8.
• Surohaldoko, S., 1983. Ecology of tempuyung (Sonchus arvensis L.) as a basis of its agronomy. Doctoral dissertation, University Gajah Mada, Yogyakarta, Indonesia. 200 pp.
• Trimurti, 1985. Development morphology of the flower and fruit of Sonchus oleraceus L. End Project Report, Department of Biology, Institute of Technology, Bandung, Indonesia.
• Tsun-Shih Hsieh, Schooler, A.B., Bell, A. & Nalewaja, J.D., 1972. Cytotaxonomy of three Sonchus species. American Journal of Botany 59(8): 789-796.

Authors

• E.B. Hidajat