Sonchus arvensis Linnaeus

Remark The words or terms in red (actually dark orange) in the text are defined in a glossary.


aug_08_06.gthmb can't be loaded. Sonchus arvensis is a vigorous herbaceous perennial, with milky sap and creeping roots that produce new shoots; the plants are up to 1.8 m tall. They are highly competitive, persistent, at times noxious, and can rapidly colonize new sites by vegetative reproduction. Introduced from Europe, it is now naturalized in North America. It was probably introduced via contaminated commercial seed. The North American sighting of the species was from Pennsylvania in 1814.

There are two varieties of Sonchus arvensis in Canada, and both varieties hybridize; they are:

In some floras these are given species status, Sonchus arvensis and Sonchus uliginosus respectively. Both have a hairless lower stem, but in Sonchus arvensis var. arvensis the upper stem and bracts have conspicuous gland-tipped hairs. Sonchus arvensis var. arvensis is most abundant in Ontario, Québec and the Atlantic provinces. Sonchus arvensis var. uliginosus is most abundant on the prairies and extends north to Great Slave Lake. And some botanists do not recognize these two varieties and state that Sonchus arvensis var. uliginosus is a synonym for Sonchus arvensis var. arvensis.

The species belongs to the Asteraceae family.

Name

Many sources, copied from one another ? say that the genus name is from the Greek sonchos, the plant's initial name, and means hollow in reference to the stem. I checked in my Dictionnaire Grec Français by Anatole Bailly, also called, Le Grand Bailly, one of the quite renowned dictionary of classical Greek, and I could not find one entry starting in σον (son) or σων (sôn), so...

In Latin, arvum means cultivated land, field, pastureland and arvus means that can be cultivated; but in the classical Dictionnaire Illustré Latin Français by Félix Gaffiot, there is no entry for arvensis. However the Botanical Latin, by William T. Stearn, Fourth Edition, has an entry for arvalis, arvensis with the definition pertaining to fields or cultivated land, and this in one of the habitat of Sonchus arvensis.

Common names

Some of the vernacular names of Sonchus arvensis are: Creeping Sow Thistle, Field Sow-thistle, Swine-thistle, Milk Thistle, Field Milk Thistle, Corn Sow-thistle, Tree Sow-thistle, Dindle and Gutweed The French vernacular name of Sonchus arvensis is Laiteron des champs in reference to the milky sap and a common habitat.

Synonyms

aug_08_07.gthmb can't be loaded. The synonymy for Sonchus arvensis, for its two varieties, is:

Identification

Sonchus arvensis is not too difficult to identify by its yellow flower heads, dandelion-like, with numerous ray flowers, by its milky sap and its spiny, prickly margins.

It can be confused with Sonchus asper or Sonchus oleraceous but the later have smaller flower heads, 1.5 to 2.5 cm in diameter. Furthermore, Sonchus asper has unlobed leaves with weak spines and Sonchus oleraceous has deeply lobed leaves that are almost spineless. (Sonchus asper and Sonchus oleraceous are annual.)

Sonchus asper is easily distinguished from Lactuca serriola that has somewhat similar flowers, but Sonchus arvensis does not have the distinctive ridge of spines on the midrib on the underside of the leaf that is associated with Lactuca serriola.

Description

Sonchus arvensis is a vigorous stout, erect, milky-juiced, deep-rooted perennial herb, from 2 to 5 feet tall, spreading by deep creeping roots. It reproduces by seed, by thick vertical roots and by cylindrical horizontal roots. In established stands, shoots and new roots begin to form when the soil warms. The shoots develop from buds that overwinter on roots or the basal portion of aerial stems. Seeds also germinate around the same time period. Plants form rosettes early in development, which provide a large photosynthetic area. The species can spread rapidly via its spreading root system. Most plants do not flower during the first-year.

Roots

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Stems

Leaves

Flower heads

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Fruits

Habitat

Sonchus arvensis thrives on non-compacted, fine, rich, slightly alkaline to neutral soils. It tolerates some salinity. It is found on bare ground, in roadsides, in disturbed sites with damp soils, in ditches and exposed soil, around sloughs and along streams.

In cultivated fields dense stands occur in oilseeds, pulses, irrigated crops and, to a lesser extent, in cereals. Seedlings are typically found along pond and river margins and in lawns, moist meadows, and uncultivated fields.

Distribution

Since its introduction to North America, Sonchus arvensis has spread widely throughout the northern United States and southern Canada. It is now found in all USA states, including Alaska but for Arizona, Oklahoma, Alabama, Georgia, South Carolina and Florida. The plant has also established in South America, Australia, and New Zealand. Widely established in temperate regions, it is not found in the tropics. map_arvensisarvensis_demi.jpg can't be loaded. map_arvensisuliginosus_demi.jpg can't be loaded. The maps, from Flora of North America show the USA States and Canadian provinces where Sonchus arvensis var. arvensis (map on the left) and Sonchus arvensis var. uliginosus (map on the right) can be found.

Sonchus arvensis occurs in all Canadian provinces and is continuing to spread north. It was found in the arctic tundra-boreal forest region of Wood Buffalo National Park, circa 60 °N, in 1962. (Buffalo National Park is Canada largest national park and one of the largest in the world; it was established in 1922 to protect the last remaining herds of bison in northern Canada; today, it protects an outstanding and representative example of Canada's Northern Boreal Plains). In Canada, it is most common in cool moist regions where it does best with little competition from perennials.

In Europe it is distributed from Scandinavia south to Italy and east to the western portions of the former Soviet Union. It is most common in the northwest, less common in central regions and rare in the south.

Remarks

Sonchus arvensis is classified as a noxious weed in many USA states and Canadian provinces; it a problem in several crops, where it causes economic losses due to reduced crop yields, increased cultivation and herbicide expenses, and land depreciation. At high densities (27 shoots/m2), it has reduced spring wheat yields up to 45 percent in North Dakota. It is also a host of several economically important plant pests. Since Sonchus arvensis is palatable to both sheep and cattle, pasturing infested land can be an effective control method.

The plant makes acceptable livestock feed and is excellent feed for rabbits and other foraging animals. In addition, the roasted roots have been used as a coffee additive or replacement, and the young leaves can be used in salads. The plant may have potential for use in oil or hydrocarbon production, since most of the latex is composed of oil. The plant is also a source of pentacyclic triterpenes, which may have use in the pharmaceutical industry. The leaves have been used as a poultice and are said to have anti-inflammatory activity. An infusion of the leaves has been used in the treatment of caked breasts (galactostasis). A tea made from the roots is used in the treatment of asthma, coughs and other chest complaints. A tea made from the leaves is said to calm the nerves.

Gallery

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The month, day and picture number might be followed by a letter:

and if there is no letter it's obviously the Minolta.

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