Species Review

Sonchus arvensis, field sowthistle

Written

November, 2004

Contributors

Jack McWilliams - 1st Author

McWilliams, Jack 2004. Sonchus arvensis, field sowthistle. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/sonarv

DOI

10.2737/feis-species-review-sonarv

Abbreviation	Common Name	Scientific Name	Classification	Status
Plants
SONARV	field sowthistle	Sonchus arvensis	Life Form: Plants/Forb Kingdom: Plantae Class: Dicot Order: Asterales Family: Asteraceae Genus: Sonchus	Fed. Protected: No Nativity: Nonnative Invasiveness: Invasive

Taxonomy

Photo of a field with a variety of green plants, the small clump in the center has long, narrow leaves with deep serrations concentrated near the base and becoming smaller and more sparse near the tops of the stems. The top of the stems branch into several yellow flowers and flower buds.

Photo Credit

Photo © Yelena, iNaturalist.org, some rights reserved.

Field sowthistle plants (CC BY-NC).

The currently accepted scientific name of field sowthistle is Sonchus arvensis L. (Asteraceae) [26,34,42,45,57,58,62,64,71,72,81,114,125,127]. There are 2 recognized subspecies:

Sonchusarvensis subsp. arvensis
Sonchusarvensis subsp. uliginosus (Bieb.) Nyman [45,72]

In this summary, field sowthistle will be used when discussing Sonchus arvensis, and the subspecies will be referred to by their scientific names when information pertaining to them individually is available.

Naturally occurring hybrids produced by the 2 subspecies have been detected in areas where both subspecies occur [74].

Synonyms

For Sonchus arvensis spp. arvensis:

Sonchus arvensis var. arvensis [26,42,64,125]

For Sonchus arvensis spp. uliginosus:

Sonchus uliginosus [34,58,71,127]
Sonchus arvensis var. glabrescens [26,42,64,114,125]

Other Common Names

perennial sowthistle, perennial sow thistle

General Distribution

Field sowthistle is of European [53,109] and western Asian [109] origin and was probably introduced into North America as a seed contaminant [75]. Sonchus arvensis spp. arvensis was first reported in 1814 in Pennsylvania [109]. The earliest collection of S. a. ssp. glabrescens in North America was from Maine in 1894. Additional collections were reported from Massachusetts and Ohio as early as 1902 [37].

Field sowthistle is reported throughout most of the United States, with the exception of Hawaii, Arizona, Oklahoma, Arkansas, Alabama, Georgia, South Carolina, and Florida. It occurs throughout Canada. Sonchus arvensis spp. arvensis has the same distribution as field sowthistle, but it is not recorded in Nebraska, Kansas, Virginia, West Virginia, North Carolina, or Alaska. Sonchus arvensis spp. uliginosus occurs across the northern portion of North America, from Alaska south to Oregon and Utah, and east to Virginia and North Carolina; but it is not reported in New Hampshire, Kentucky, British Columbia or the far northern territories of Canada [65].

No specific mention of field sowthistle in Mexico occurs in the literature. Since it occurs in Texas and New Mexico, it is reasonable to assume it may also occur in northern Mexico.

Plants database provides a state distribution map of field sowthistle and its infrataxa.

Table A1 in the Appendix lists include North American ecosystems, habitat types, and forest and range cover types in which field sowthistle may occur. Field sowthistle grows well in wet and even saturated soils. Consequently, field sowthistle may occur in riparian areas or wetlands within these habitats. Additionally, field sowthistle often occurs in cultivated areas, especially small grain and row crops, so it may occur in cultivated areas within these communities, with the potential to spread into adjacent, undisturbed areas.

States and Provinces

United States: AK CA CO CT DE ID IL IN IA KS KY LA ME MD MA MI MN MS MO MT NE NV NH NJ NM NY NC ND OH OR PA RI SD TN TX UT VT VA WA WV WI WY DC
Canada: AB BC MB NB NF NT NS NU ON PE PQ SK YK
Mexico

Site Characteristics

Field sowthistle is adapted to moist, sunny locations in temperate regions but is absent from tropical areas [74]. Within temperate regions, field sowthistle has a broad tolerance to variable environments and adapts well to wet sites, even with little soil disturbance. In Canada, field sowthistle occurs in areas that receive average annual precipitation of 12 to 120 inches (300-3,000 mm) [133]. In a greenhouse study, growth of field sowthistle plants was positively correlated with increasing soil water, with greatest growth occurring at complete saturation [132]. However, field sowthistle also establishes on dry sites [98]. Neither the climatic conditions required for successful establishment nor conditions, if any, favoring S. a. ssp. arvensis over S. a. ssp. uliginosus have been established [74].

Field sowthistle is adapted to many soil types but appears to prefer fine-textured soils and does not thrive on dry, coarse-textured sand. Field sowthistle seems to prefer slightly alkaline or neutral soils and does not thrive in acid soils, salt marshes, or highly alkaline areas [110]. However, Zollinger and Kells [132] determined soil pH had little effect on leaf production, plant height, or number of capitula produced.

Field sowthistle is present in a variety of community types from those occurring on wet, very strongly saline surface soil and strongly saline subsoil to nonsaline and dry soils [98]. Dodd and Coupland [33] describe field sowthistle as occurring in halophytic or semihalophytic communities in Saskatchewan.

Plant Communities

Field sowthistle is found in a wide range of habitats. It occurs in cultivated fields of both small grains and row crops, in disturbed areas, "waste grounds," meadows, sloughs, woods, lawns, and along roadsides, beaches, ditches, and river and lake shores [109,110]. Although field sowthistle is adapted to many habitats, it is mentioned most often in the literature in relation to saline habitat types.

Field sowthistle is found on disturbed sites in saline habitats in Saskatchewan, Manitoba, and Alberta in association with rayless alkali aster (Symphyotrichumciliatum), spear saltbush (Atriplexpatula), curlycup gumweed (Grindelia squarrosa), summer-cypress (Kochia scoparia), Nuttall's alkaligrass (Puccinellianuttalliana), red swampfire (Salicorniarubra), and Pursh seepweed (Suaedacalceoliformis) [16].

Major species associated with S. a. ssp. uliginosus in halophytic or semihalophytic communities in Saskatchewan near saline depressions include western yarrow (Achillea millefolium), rosy pussytoes (Antennaria microphylla), manyflowered aster (Symphyotrichumericoides var. pansum), saltgrass (Distichlis spicata), wild licorice (Glycyrrhiza lepidota), foxtail barley (Hordeum jubatum), mat muhly (Muhlenbergia richardsonis), and gray goldenrod (Solidagonemoralis) [33].

Redmann [98] described plant communities along a soil salinity-moisture gradient of an eastern North Dakota prairie. Field sowthistle was present in every plant community except the muhly (Muhlenbergia spp.) and bluestem (Andropogon spp.) types. In a prairie cordgrass (Spartina pectinata) community, field sowthistle commonly occurs with foxtail barley, slender wheatgrass (Elymus trachycaulus), scratchgrass (M. asperifolia), mat muhly, bluejoint reedgrass (Calamagrostis canadensis), northern bog aster (Symphyotrichum boreale), and marsh hedgenettle (Stachys palustris). In a bluegrass (Poa spp.) community type, field sowthistle occurs at lower elevations with foxtail barley, scratchgrass, wild licorice, and Maximilian sunflower (Helianthus maximiliani). Sonchus arvensis ssp. uliginosus is found in a "salt flat" area, or saltgrass community type, with saltgrass, serpentine aster (Symphyotrichumericoides), curlycup gumweed, alkali cordgrass (Spartina gracilis), foxtail barley, slender wheatgrass, scratchgrass, and plains bluegrass (Poa arida). Itis alsofound in the foxtail barley community type where it occurs with plains bluegrass, scratchgrass, curlycup gumweed, serpentine aster, curly dock (Rumex crispus), prairie wedgescale (Sphenopholis obtusata), and Cuman ragweed (Ambrosiapsilostachya) [98].

Botanical Description

Photo of a hand holding the branched top of a green plant stem, with a yellow flower or unopened flowerbud at the end of each branch.

Photo Credit

Photo © Elizabeth Axley, iNaturalist.org, some rights reserved.

Field sowthistle flowers (CC BY).

The following description of field sowthistle provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available in these sources: [26,34,42,45].

Field sowthistle is a perennial herb [53,74] that reproduces by seeds, by vertical, thickened roots, and by cylindrical, horizontal, spreading roots [110]. Vertical roots can penetrate 5 to10 feet (1.5-3 m) deep. Horizontal roots, frequently 2.5 to 5 mm in diameter (rarely exceeding 10 mm), are found 2 to 4 inches (5-10 cm) below the soil surface [10]. These horizontal roots can reach 3 to 6 feet (0.9-1.8 m) in length in a single growing season [110]. Fruits are achenes [15,90] with a pappus that generally stays attached to the achene [92].

Stems are erect, 0.1 to 0.4 inches (3-10 mm) in diameter, and most commonly 24 to 59 inches (60-150 cm) tall; although they range from 12 to 71 inches (30-180 cm) tall. Stems are hollow and branched, varying from 2 to many per plant. Leaves are crowded on the lower stems and sparse on the upper stems. The entire plant is filled with milky latex [74].

Raunkiaer Life Form

Hemicryptophyte [97]

Seasonal Development

Shoots and new roots in established stands begin to develop when the soil starts to warm [51,110]. Small leaves begin to appear from shallow roots about 1 week from initial growth [110], and adventitious root development begins 3 to 4 weeks later. Initial thickening of new roots begins when plants have 5 to 7 leaves [50,52]. Secondary thickening proceeds quickly, and spreading roots 4 mm thick and over 79 inches (200 cm) long can be detected by 3 months after initial growth [110]. Thickening of new roots ceases by mid-summer. New shoots develop from roots 2-3 mm in diameter until late summer [74].

Flowering stems begin to develop when plants have 12 to 15 leaves [50,110]. Flowering begins about 1 July in the northern United States and continues until plants are frosted, although most flowering is complete by late summer [110]. Time required from flowering to fruit maturation is about 10 days [74].

Regeneration Processes

Photo of the flowering top a green plant with long, narrow, deeply serrated leaves growing among other green plants. The flowers have mostly closed and gone to seed, which appear as fluffy, white, spherical bundles.

Photo Credit

Photo © Bob, iNaturalist.org, some rights reserved.

Field sowthistle seedheads (CC BY).

Field sowthistle can reproduce by seed and vegetatively [10,30,110].

Pollination and Breeding System

Field sowthistle is pollinated by insects including honeybees and other bees, hover flies, and blister beetles [31,110]. Field sowthistle flowers are perfect [31] and generally self-incompatible [31,110].

Seed Production

Field sowthistle can produce large numbers of seeds [31,53,110,112]. Seeds produced by self pollination are generally nonviable and smaller than those produced by cross-pollination [31,110].

Heads contain many fertile flowers but the number of achenes produced varies widely among heads, plants, and locality. Variability likely results from several factors, including environmental conditions and availability of pollinators [110].

Field sowthistle can typically produce an average of 30 achenes per head and up to 50,000/yd² [110]. In North Dakota, 1 main stalk, with "relatively little competition", produced 62 heads and 9,750 well-developed achenes. The author collected seeds from the plant for a 30-day period [112]. In South Dakota, artificially cross-pollinated heads from greenhouse- and field-grown plants produced about 50 achenes per head, but number of achenes per head in natural populations varied from about 20 to 40 or from 60 to 80, depending upon the year [31].

Seed Dispersal

Seeds of field sowthistle are mostly wind dispersed [28,53,110], but other dispersal agents may play a minor role. The pappus, attached to the seed, aids in wind dispersal [92]. Hume and Archibold [63] placed seed traps at varying distances from a "weedy" field in Saskatchewan. Results show wind-blown seeds of field sowthistle can disperse at least 110 yards (100 m). They do not report wind speed.

Sheldon and Burrows [105] conducted experiments to determine maximum dispersal distance of field sowthistle seeds at differing wind speeds. They used field sowthistle plants with a mean height of 3 feet (90 cm). They observed a maximum dispersal distance of 11 yards (10 m).

Wind speed (km/hour)	5.47	10.94	16.41
Dispersal distance (m)	3.34	6.67	10.00

In addition to wind dispersal, seeds of field sowthistle may be dispersed by birds and other animals. Martin and others (as reported in [133], a literature review) state field sowthistle is a minor element in the diet of some North American birds, and some seeds may germinate after ingestion and excretion by birds and animals. Hooked cells at the tips of pappus hairs allow the pappus to cling to clothes and animal hairs and aid in seed dispersal [110,133].

Seed Banking

While viable field sowthistle seeds have been found in the seed banks of marshes and wetlands [60,88], longevity of seeds in the soil seed bank under field conditions of these communities is unknown. A study of field sowthistle seed dormancy suggests that some seed may remain viable for 3 or more years in cultivated soils [23].

Seed banking studies in the Delta Marsh, Manitoba, suggest that viable field sowthistle seeds occur in marsh habitats. Sowthistles (Sonchus spp.) were dominant in the drier upland areas, so seed was likely dispersed throughout the marsh. Field sowthistle seedlings emerged from soil samples taken from the marsh and exposed to "drawdown" conditions (soil surface kept moist), but not from samples exposed to "submersed" conditions (continuously flooded to a depth of 2 to 3 cm above the soil surface) [88].

In an experiment designed to test seedling emergence from boreal wetland soils under changing climatic conditions, field sowthistle seedlings emerged from the soil seed bank in willow (Salix spp.) savanna and bluejoint reedgrass vegetation zones of a mid-boreal wetland in Alberta [60].

Although seeds of field sowthistle have low viability in cultivated fields, some can remain dormant but viable for more than 3 years in cultivated soil. Chepil [23] conducted 3 separate seed dormancy tests for "weed" species in cultivated soil in Saskatchewan. In the 1st experiment an indefinite number of field sowthistle seeds was planted in 3 soil types on 18 September, 1937. Introduction of seeds from other sources was prevented. No seeds were planted greater than 3 inches (7.6 cm) deep. Number of viable seeds remaining in the soil after 3 years was determined by repeated germination tests in the laboratory until no more germination occurred. Results are shown in the table below [23]:

Percentage of field sowthistle seeds germinated each year after planting in 3 soil types in 1937 [23].
Soil texture	1938	1939	1940	Viable seeds remaining
Clay	43.3	16.2	2.7	37.8
Loam	66.7	13.3	0	20.0
Sandy loam	86.7	0	3.3	10.0

In the 2nd experiment, 50 field sowthistle seeds were planted no deeper than 3 inches (7.6 cm) on 14 October, 1938, in 3 soil types. Again, number of viable seeds remaining in the soil after 6 years was determined by repeated germination tests in the laboratory until no more germination occurred. Values given are number of viable seeds [23].

Number of viable filed sowthistle seeds remaining in the soil each year after planting 50 seeds in each of 3 soil types [23].
Soil texture	1939	1940	1941	Viable seeds remaining
Clay	33	0	4	0
Loam	1	0	0	0
Sandy loam	2	3	0	1

The 3rd experiment utilized 1,000 field sowthistle seeds planted no deeper than 3 inches (7.6 cm). Seeds were planted between 1 and 5 November, 1940, in 3 soil types and only seeds germinated in the field were counted. Numbers are actual seeds germinating, not percentages [23].

Soil texture	1941	1943	1944
Clay	18	2	5
Loam	16	0	0
Sandy loam	12	0	1

Clay appears to be most conducive to long-term viability of field sowthistle seeds [23] (see Site Characteristics).

Germination

Germination of field sowthistle seeds increases with both increasing soil temperature and time since flowering. Field sowthistle seed in the field begins to germinate when the soil has "warmed" [74].

Seeds may be capable of germination about 5 days after pollination [74]; however, germination rates increased from low to none 4 days after flowering to a maximum 7 to 9 days after flowering [31,66,110]. In field germination experiments in South Dakota, Derscheid and Schultz [31] noted that percentage of viable seeds produced by field sowthistle ranged from 10% 6 days after blooming to 89% 9 days after blooming. If field sowthistle plants are pulled or cut and placed in a pile it is possible for viable seeds to be produced if flowers are present when the plants are cut [110].

In laboratory germination tests, field sowthistle seed viability is "relatively" high. Kinch and Termunde [66] achieved 95% germination in the laboratory using "well-matured" seed.

Orientation of field sowthistle seeds in the soil profile is important to germination, and light may stimulate germination. Bosy and Aarssen [15] conducted seed germination tests on field sowthistle using agar as a germinating medium. Agar was used to eliminate any environmental differences at a given depth and enabled the authors to maintain seed orientation. They found surface-lying seeds of field sowthistle displayed higher germination than buried seeds [15]. Germination was 50% for seeds germinated in soil and 80% for seeds germinated on moist filter paper, and germination was higher in diffuse laboratory light than in complete darkness [90]. When seeds were buried, seeds oriented with the radicle horizontal had significantly greater (P<0.05) germination than seeds with the radicle oriented either upward or downward.

Studies indicate temperatures from 77 to 86 °F (25-30 °C) are optimal for germination. Seeds germinate poorly (<5%) below 68 °F (20 °C) and above 95 °F (35 °C), but alternating temperatures were more favorable for germination than constant temperatures if temperatures above 77 °F (25 °C) are included in the cycle [52]. Stevens [110] reports seeds exposed to 90 °F (32 °C) for a "few hours daily" germinate "freely" in 4 to 7 days.

Field sowthistle seed germination in wetlands could be limited by saturated soils. For example, Hogenbirk and Wein [60] germinated seeds of field sowthistle from combined soil and litter samples from a mid-boreal wetland in Alberta. No field sowthistle seeds germinated in samples taken from a sedge (Carex spp.) marsh. Field sowthistle seeds stored in fresh water were 100% decomposed after 3 months storage [18].

Seedling Establishment and Growth

Field sowthistle seedlings survive best in areas with protective plant cover or litter and high moisture compared with open cultivated soil [110]. Accordingly, seedlings are often only found along pond, ditch, or field margins, or in lawns, meadows, or uncultivated fields [92]. In a series of field germination experiments with field sowthistle seeds, Stevens [110] had little success growing seedlings in cultivated field plots. Laboratory germination tests with the same lot of seeds showed 56% germination.

Most field sowthistle seedlings do not emerge until mid- to late May in Saskatchewan and the Great Plains of the United States [74]. Seedlings grow slowly for about the first 2 weeks until leaves are about 1.2 inches (3 cm) long [110]. They develop rapidly after that, and reproductive ability of spreading roots is established quickly [52,110]. Stevens [110] noted 10 seedlings on 17 May, 1923. The 10 seedlings grew slowly until 1 June when the largest leaves were 1.2 inches (3 cm) long. After that, they developed "rapidly" and on 5 July, a horizontal root 28 inches long (71 cm) was removed from the largest plant [110].

Most seedlings do not flower the first year, but flowering in late summer is possible from some first-year seedlings in favorable environments [52,110].

Vegetative Reproduction and Regeneration

Field sowthistle reproduces vegetatively from buds on horizontal and vertical roots and on basal portions of aerial stems located just under the soil surface. Thickened roots develop as a result of secondary growth of original fibrous roots [51] and begin to show reproductive capacity when thickened to 1 to 1.5 mm [50]. This occurs on vertical primary roots when seedlings reach the 4-leaf stage and on horizontal roots when seedlings have 6 to 7 photosynthetic leaves. One-month-old seedlings can have 7 to 8 leaves with horizontal roots from 4 to 6 inches (10-15 cm) long and 1.5 mm thick. Horizontal roots from 24 to 39 inches (60-100 cm) and vertical roots penetrating 20 inches (50 cm) can develop from seedlings within 4 months after emergence. Vertical roots can produce vegetative buds as deep as 20 inches (50 cm) below the soil surface, and new aerial growth has been observed from buds as deep as 16 inches (40 cm) below the soil surface [110]. New shoots can develop from buds that overwinter on both vertical and horizontal "spreading" roots, and/or on basal portions of aerial stems [51,89]. In North Dakota, the rate of vegetative spread of field sowthistle clones varied from 1.6 to 9 feet (0.5-2.8 m) per year, depending on the clone (personal observation in [74]).

Harris and Shorthouse [53] describe the horizontal roots of field sowthistle as "easily broken", and new plants can grow from root fragments and flower within 1 year [50,110]. Of field sowthistle root fragments planted on 3 May in a field experiment in North Dakota, approximately 50% of 0.25-inch-long pieces, 75% of 0.5-inch-long pieces, and 85% of 1-inch-long pieces produced plants within 20 to 34 days. Where well developed buds were present on root fragments, plants emerged quickly and were strong; if buds were not present, new plants grew more slowly from the cut surface and were weak. Plants grown from these root fragments reached a height of 3 feet (1 m) and flowered abundantly between 27 July and 6 August. On 29 June the largest of these plants had 2 horizontal roots 42 to 45 inches long (107-114 cm). The 45-inch root had 42 buds and sprouts in various stages of development. By the end of the growing season, horizontal roots from these plants reached about 6 feet (1.8 m) in length [110].

Successional Status

Field sowthistle is an early-successional plant. Komarova [67] and Zollinger and Parker [133] describe field sowthistle as a pioneer species. In a study of succession after fire in "highland hardwoods" in Wisconsin, it appeared in 6 out of 10 plots in the herbaceous stage of succession [44]. Although infrequent, field sowthistle is part of the early successional community on wetlands in the blast zone after the Mount St. Helen's eruption [121].

Field sowthistle is most competitive under abundant precipitation and moderate climates [133].

Immediate Fire Effects

As of this writing (2004), no accounts in the literature discuss or describe immediate effects of fire on field sowthistle plants or seeds. It is reasonable to assume that field sowthistle plants are top-killed by fire and that some underground regenerating organs survive even high-severity fire (see Fire Adaptations).

Postfire Regeneration Strategy

Geophyte, growing points deep in soil
Ground residual colonizer (on-site, initial community)
Initial off-site colonizer (off-site, initial community) [113]

Fire Adaptations

As of this writing (2004), no information is available specifically addressing fire adaptations in field sowthistle; however, inferences regarding its ability to establish, persist, and spread after fire are possible, based on its regeneration strategies and data from a small number of fire studies in which field sowthistle occurred.

Field sowthistle seeds are dispersed by wind (see Seed dispersal), and seedlings may establish on burned areas from offsite seed sources when mature plants occur in the vicinity of the burn. Seedlings established on burned sites in red pine forest in Minnesota [3] and on the Delta Marsh in Manitoba [120], while no field sowthistle plants occurred on unburned control plots in either study. Probability of postfire establishment from offsite seed may be related to season of burning (see Plant Response to Fire). Information on seed banking for field sowthistle suggests that it is possible for seedlings to establish from the soil seed bank after fire, although this has not been documented in the available literature.

Field sowthistle plants are likely to survive and persist on burned areas, even after high-severity fire, and the limited available data on postfire response of field sowthistle indicate little difference in abundance between burned and unburned sites [59,86] (see Plant response to fire). Field sowthistle shoots develop from numerous underground buds on both vertical and horizontal roots, and on basal portions of aerial stems [51,89] (see Asexual regeneration). Vertical roots can be 5 to 10 feet (1.5-3 m) deep [10] with the potential to produce shoots from buds as deep as 16 inches (40 cm) below the soil surface [110]. These buds would not be affected by fire. Horizontal roots of field sowthistle occur 2 to 4 inches (5-10 cm) below the surface [10] and would probably also be protected from all but the most severe fires.

Plant Response to Fire

Field sowthistle can establish on burned sites from wind-dispersed seed, as suggested by results of studies in red pine (Pinus resinosa) forest in Minnesota [3] and on the Delta Marsh in Manitoba [120]. Field sowthistle seedlings may be more likely to establish on burned sites after summer fires, when field sowthistle plants are likely to be dispersing seed, than following fall or spring fires [120].

Established field sowthistle plants are likely to persist after fire on burned sites, though it is unclear whether its overall abundance will increase or decrease in the postfire environment. Postfire data from studies in Alberta, Canada [59] and North Dakota [86] shows little difference between burned and unburned sites, and no detectable postfire trend in field sowthistle abundance 1 to 2 years after fire.

Flowering of field sowthistle may increase after fire. Postfire flowering response may be related to postfire moisture availability [91].

Field sowthistle may establish on burned sites from wind-dispersed seed. Soil samples were taken from burned and unburned areas of a 270-year-old red pine forest in Minnesota 3 years after wildfire. No field sowthistle germinants emerged from soil taken from unburned areas, while the equivalent of 109,000 field sowthistle seedlings per hectare emerged from soil taken from burned areas. No field sowthistle plants occurred in either burned or unburned plots, and no field sowthistle seeds were found in unburned soil samples. The author concluded that field sowthistle seedlings probably developed from seeds blown into the burned areas after the fire [3].

Probability of postfire establishment from offsite seed sources may be related to season of burning. Thompson and Shay [120] conducted 3 prescribed burn treatments in 3 different seasons on the Delta Marsh in Manitoba. Field sowthistle was absent from unburned plots, but seedlings established on both summer and fall burned plots, with greatest establishment 1 month following summer burns. These seedlings persisted into the following year, resulting in increased nonseedling shoot density and biomass on summer burned plots:

Mean values (95% CI) for 3 variables of field sowthistle following burning during different seasons at the Delta Marsh, Manitoba [120].
Variable	Plot type/burn date/sample date
Variable	Control	August 1979 burn, sampled September 1979	August 1979 burn, sampled August 1980	October 1979 burn, sampled August 1980	May 1980 burn, sampled August 1980
Seedling density (seedlings/m²)	0	15.5 (11.5)	0	0.4 (0.4)	0
Nonseedling shoot density (stems/m²)	0	—	8 (1.7)	0	0
Biomass (g/m²)	0	—	28.2 (16.9)	0.1 (0.2)	0

Field sowthistle has a long flowering period that begins in early July and continues until plants are frosted, with peak flowering in mid to late summer [110]. Summer burns on the Delta Marsh were conducted at the time of year when the most mature sowthistle seed was likely being dispersed, while timing of fall burns corresponded to a time of year when fewer seeds were likely to be available, and spring burns occurred when no field sowthistle seed would likely be available [120]. Although there is evidence that field sowthistle seeds occur in the soil seed bank in the Delta Marsh [88] (see seed banking), it is more likely that field sowthistle seedlings detected in this study [120] established from wind-dispersed seed, given the correspondence of burn season, field sowthistle phenology, and seedling establishment.

While field sowthistle is likely to persist after fire, data are insufficient for detecting trends in its postfire abundance. Simulated "light" and "deep" burns using a propane torch in both bluejoint reedgrass and willow savanna habitats in northern Alberta found little difference in field sowthistle cover 2 growing seasons after summer burning [59]:

Mean percent cover (SE) of field sowthistle following experimental burn treatments in 2 community types in Alberta [59].
Plant community	Burn treatment
Plant community	None	Light	Deep
Bluejoint reedgrass meadow	1 (1)	2 (1)	4 (2)
Willow savanna	10 (3)	15 (5)	15 (4)

Abundance of field sowthistle plants was highly variable on burned and unburned prairie sites in a study to evaluate the effects of prescribed burning on grassland species desired for wildlife habitat on the Tewaukon National Wildlife Refuge in southeastern North Dakota. Cover of field sowthistle was mostly the same on burned and unburned sites, but in some years was either significantly higher on or significantly lower on burned versus control plots. Data show both great variation in percent canopy cover and no clear trend of increase or decrease on burned versus control plots, 1 month or 26 months after fires in May or June [86].

In northwestern Minnesota, flowering of field sowthistle increased on some sites after prescribed fire was used as part of a prairie restoration project. Burns were conducted in spring 1973, and data on flowering response were collected during the growing season of the same year. Results were based on comparison of burned and unburned transects. Field sowthistle was recorded on 3 site types in the study area: a wet-mesic site in "badly" disturbed prairie, a wet swale site in undisturbed prairie, and a gently sloping to nearly level mesic site in undisturbed prairie. Flowering increased after prescribed fire, relative to controls, on both disturbed and undisturbed wet prairie sites, but was not different from controls in the mesic prairie site [91].

Fire Regimes

As of this writing (2004), no information regarding fire regimes in which field sowthistle evolved was found in the available literature; nor was information available regarding impacts of field sowthistle invasion on fuel characteristics or fire regimes in native North American plant communities.

The following table provides fire return intervals for plant communities and ecosystems where field sowthistle may occur in North America. Field sowthistle may also occur within riparian or wetland areas included in these ecosystems. For additional fire regime information, search FEIS for this species by entering the species name on the Advanced Search page and selecting “Fire Regime” as the publication type.

Community or Ecosystem	Dominant Species	Fire Return Interval Range (years)
silver fir-Douglas-fir	Abies amabilis-Pseudotsuga menziesii var. menziesii	> 200
grand fir	Abies grandis	35-200 [6]
maple-beech-birch	Acer-Fagus-Betula	> 1,000
silver maple-American elm	Acer saccharinum-Ulmus americana	< 35 to 200
sugar maple	Acer saccharum	> 1,000
sugar maple-basswood	Acer saccharum-Tilia americana	> 1,000 [126]
California chaparral	Adenostoma and/or Arctostaphylos spp.	< 35 to < 100 [87]
bluestem prairie	Andropogon gerardii var. gerardii-Schizachyrium scoparium	< 10 [68,87]
Nebraska sandhills prairie	Andropogon gerardii var. paucipilus-Schizachyrium scoparium	< 10
bluestem-Sacahuista prairie	Andropogon littoralis-Spartina spartinae	< 10 [87]
silver sagebrush steppe	Artemisia cana	5-45 [56,96,130]
sagebrush steppe	Artemisia tridentata/Pseudoroegneria spicata	20-70 [87]
basin big sagebrush	Artemisia tridentata var. tridentata	12-43 [101]
mountain big sagebrush	Artemisia tridentata var. vaseyana	15-40 [8,22,80]
Wyoming big sagebrush	Artemisia tridentata var. wyomingensis	10-70 (40**) [124,131]
coastal sagebrush	Artemisia californica	< 35 to < 100
saltbush-greasewood	Atriplex confertifolia-Sarcobatus vermiculatus	< 35 to < 100
desert grasslands	Bouteloua eriopoda and/or Pleuraphis mutica	5-100 [87]
plains grasslands	Bouteloua spp.	< 35 [87,130]
blue grama-needle-and-thread grass-western wheatgrass	Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii	< 35 [87,100,130]
blue grama-buffalo grass	Bouteloua gracilis-Buchloe dactyloides	< 35 [87,130]
grama-galleta steppe	Bouteloua gracilis-Pleuraphis jamesii	< 35 to < 100
blue grama-tobosa prairie	Bouteloua gracilis-Pleuraphis mutica	< 35 to < 100 [87]
cheatgrass	Bromus tectorum	< 10 [95,128]
California montane chaparral	Ceanothus and/or Arctostaphylos spp.	50-100 [87]
sugarberry-America elm-green ash	Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica	< 35 to 200 [126]
paloverde-cactus shrub	Cercidium microphyllum/Opuntia spp.	< 35 to < 100 [87]
curlleaf mountain-mahogany*	Cercocarpus ledifolius	13-1,000 [9,103]
mountain-mahogany-Gambel oak scrub	Cercocarpus ledifolius-Quercus gambelii	< 35 to < 100 [87]
Atlantic white-cedar	Chamaecyparis thyoides	35 to > 200 [126]
blackbrush	Coleogyne ramosissima	< 35 to < 100
Arizona cypress	Cupressus arizonica	< 35 to 200
northern cordgrass prairie	Distichlis spicata-Spartina spp.	1-3 [87]
beech-sugar maple	Fagus spp.-Acer saccharum	> 1,000 [126]
California steppe	Festuca-Danthonia spp.	< 35 [87,115]
black ash	Fraxinus nigra	< 35 to 200
juniper-oak savanna	Juniperus ashei-Quercus virginiana	< 35
Ashe juniper	Juniperus ashei	< 35
western juniper	Juniperus occidentalis	20-70
Rocky Mountain juniper	Juniperus scopulorum	< 35 [87]
cedar glades	Juniperus virginiana	3-22 [49,87]
tamarack	Larix laricina	35-200 [87]
western larch	Larix occidentalis	25-350 [13,29]
creosotebush	Larrea tridentata	< 35 to < 100
Ceniza shrub	Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa	< 35 [87]
yellow-poplar	Liriodendron tulipifera	< 35 [126]
wheatgrass plains grasslands	Pascopyrum smithii	< 5-47+ [87,96,130]
Great Lakes spruce-fir	Picea-Abies spp.	35 to > 200
northeastern spruce-fir	Picea-Abies spp.	35-200 [35]
southeastern spruce-fir	Picea-Abies spp.	35 to > 200 [126]
Engelmann spruce-subalpine fir	Picea engelmannii-Abies lasiocarpa	35 to > 200 [6]
black spruce	Picea mariana	35-200
conifer bog*	Picea mariana-Larix laricina	35-200 [35]
blue spruce*	Picea pungens	35-200 [6]
red spruce*	Picea rubens	35-200 [35]
pine-cypress forest	Pinus-Cupressus spp.	< 35 to 200 [6]
pinyon-juniper	Pinus-Juniperus spp.	< 35 [87]
whitebark pine*	Pinus albicaulis	50-200 [2,4]
jack pine	Pinus banksiana	<35 to 200 [35]
Mexican pinyon	Pinus cembroides	20-70 [82,117]
Rocky Mountain lodgepole pine*	Pinus contorta var. latifolia	25-340 [12,13,119]
Sierra lodgepole pine*	Pinus contorta var. murrayana	35-200 [6]
shortleaf pine	Pinus echinata	2-15
shortleaf pine-oak	Pinus echinata-Quercus spp.	< 10 [126]
Colorado pinyon	Pinus edulis	10-400+ [39,43,87]
slash pine	Pinus elliottii	3-8
slash pine-hardwood	Pinus elliottii-variable	< 35 [126]
Jeffrey pine	Pinus jeffreyi	5-30
western white pine*	Pinus monticola	50-200 [6]
longleaf-slash pine	Pinus palustris-P. elliottii	1-4 [85,126]
longleaf pine-scrub oak	Pinus palustris-Quercus spp.	6-10 [126]
Pacific ponderosa pine*	Pinus ponderosa var. ponderosa	1-47 [6]
interior ponderosa pine*	Pinus ponderosa var. scopulorum	2-30 [6,11,73]
Arizona pine	Pinus ponderosa var. arizonica	2-15 [11,25,104]
Table Mountain pine	Pinus pungens	< 35 to 200 [126]
red pine (Great Lakes region)	Pinus resinosa	10-200 (10**) [35,40]
red-white-jack pine*	Pinus resinosa-P. strobus-P. banksiana	10-300 [35,54]
pitch pine	Pinus rigida	6-25 [21,55]
pocosin	Pinus serotina	3-8
pond pine	Pinus serotina	3-8
eastern white pine	Pinus strobus	35-200
eastern white pine-eastern hemlock	Pinus strobus-Tsuga canadensis	35-200
eastern white pine-northern red oak-red maple	Pinus strobus-Quercus rubra-Acer rubrum	35-200
loblolly pine	Pinus taeda	3-8
loblolly-shortleaf pine	Pinus taeda-P. echinata	10 to < 35
Virginia pine	Pinus virginiana	10 to < 35
Virginia pine-oak	Pinus virginiana-Quercus spp.	10 to < 35
sycamore-sweetgum-American elm	Platanus occidentalis-Liquidambar styraciflua-Ulmus americana	< 35 to 200 [126]
galleta-threeawn shrubsteppe	Pleuraphis jamesii-Aristida purpurea	< 35 to < 100
eastern cottonwood	Populus deltoides	< 35 to 200 [87]
aspen-birch	Populus tremuloides-Betula papyrifera	35-200 [35,126]
quaking aspen (west of the Great Plains)	Populus tremuloides	7-120 [6,47,79]
mesquite	Prosopis glandulosa	< 35 to < 100 [78,87]
mesquite-buffalo grass	Prosopis glandulosa-Buchloe dactyloides	< 35
Texas savanna	Prosopis glandulosa var. glandulosa	< 10
black cherry-sugar maple	Prunus serotina-Acer saccharum	> 1,000 [126]
mountain grasslands	Pseudoroegneria spicata	3-40 (10**) [5,6]
Rocky Mountain Douglas-fir*	Pseudotsuga menziesii var. glauca	25-100 [6,7,8]
coastal Douglas-fir*	Pseudotsuga menziesii var. menziesii	40-240 [6,83,99]
California mixed evergreen	Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii	< 35
California oakwoods	Quercus spp.	< 35 [6]
oak-hickory	Quercus-Carya spp.	< 35 [126]
oak-juniper woodland (Southwest)	Quercus-Juniperus spp.	< 35 to < 200 [87]
northeastern oak-pine	Quercus-Pinus spp.	10 to < 35 [126]
oak-gum-cypress	Quercus-Nyssa-spp.-Taxodium distichum	35 to > 200 [85]
southeastern oak-pine	Quercus-Pinus spp.	< 10 [126]
coast live oak	Quercus agrifolia	2-75 [46]
white oak-black oak-northern red oak	Quercus alba-Q. velutina-Q. rubra	< 35 [126]
canyon live oak	Quercus chrysolepis	<35 to 200
blue oak-foothills pine	Quercus douglasii-P. sabiniana	< 35 [6]
northern pin oak	Quercus ellipsoidalis	< 35 [126]
Oregon white oak	Quercus garryana	< 35 [6]
bear oak	Quercus ilicifolia	< 35 [126]
California black oak	Quercus kelloggii	5-30 [87]
bur oak	Quercus macrocarpa	< 10 [126]
oak savanna	Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium	2-14 [87,126]
shinnery	Quercus mohriana	< 35 [87]
chestnut oak	Quercus prinus	3-8
northern red oak	Quercus rubra	10 to < 35
post oak-blackjack oak	Quercus stellata-Q. marilandica	< 10
black oak	Quercus velutina	< 35
live oak	Quercus virginiana	10 to< 100 [126]
interior live oak	Quercus wislizenii	< 35 [6]
cabbage palmetto-slash pine	Sabal palmetto-Pinus elliottii	< 10 [85,126]
blackland prairie	Schizachyrium scoparium-Nassellaleucotricha	< 10
Fayette prairie	Schizachyrium scoparium-Buchloe dactyloides	< 10 [126]
little bluestem-grama prairie	Schizachyrium scoparium-Bouteloua spp.	< 35
tule marshes	Scirpus and/or Typha spp.	< 35 [87]
redwood	Sequoia sempervirens	5-200 [6,38,116]
southern cordgrass prairie	Spartina alterniflora	1-3 [87]
baldcypress	Taxodium distichum var. distichum	100 to > 300
pondcypress	Taxodium distichum var. nutans	< 35 [85]
western redcedar-western hemlock	Thuja plicata-Tsuga heterophylla	> 200 [6]
eastern hemlock-yellow birch	Tsuga canadensis-Betula alleghaniensis	> 200 [126]
western hemlock-Sitka spruce	Tsuga heterophylla-Picea sitchensis	> 200
mountain hemlock*	Tsuga mertensiana	35 to > 200 [6]
elm-ash-cottonwood	Ulmus-Fraxinus-Populus spp.	< 35 to 200 [35,126]
fire return interval varies widely; trends in variation are noted in the species review *mean

Fire Management Considerations

Postfire Colonization Potential

Field sowthistle may establish on burned sites after fire [3,120], especially when burning is conducted during the flowering period [120]. Managers should be alert to this possibility when field sowthistle occurs in the vicinity of the burn area. Additionally, flowering of field sowthistle may be stimulated by prescribed burning [91], resulting in increased seed production and further increasing the likelihood of postfire establishment.

Prescribed Fire as a Control Agent

While no research is available examining the potential for using prescribed fire to control field sowthistle, evidence from other fire studies [59,86] suggest that it is likely to persist after fire and may increase in abundance on some sites. Given the abundance of underground buds on both vertical and horizontal roots, and on basal portions of aerial stems [51,89], it is unlikely that prescribed fire would be severe enough to substantially damage established field sowthistle plants.

If field sowthistle plants are pulled or cut and placed in a pile it is possible for viable seeds to be produced if flowers are present when the plants are cut. These plants could be burned to reduce the possibility of viable seeds being produced [110].

Federal Status

None

Other Status

As of this writing (2004), field sowthistle is listed as a noxious weed in 13 states. More information is available through the Plants database.

Importance to Wildlife and Livestock

Field sowthistle is "good" as a livestock feed [111,129]. Sheep and cattle will eat new growth and sometimes roots [133], and pronghorns were observed utilizing field sowthistle in central Montana during the fall [24].

Field sowthistle is considered "excellent" forage for rabbits [118] and Martin and others (as reported in [133], a literature review) state field sowthistle is a minor element in the diet of some North American birds.

Field sowthistle is listed as a nonnative plant occurring in critical habitat of the threatened desert tortoise in the Mojave and Colorado deserts. It is of concern because it competes with native plants vital to the tortoises' survival [17].

Palatability and Nutritional Value

Although field sowthistle compares favorably with alfalfa (Medicago sativa) for nutritional value, it is not especially palatable to grazing animals. Dry field sowthistle is about 10% protein by weight [19,20]. Palatability of field sowthistle to lambs was lower compared to grasses and alfalfa, and infestations of field sowthistle in pastures and hayfields may decrease overall forage feeding value [76].

Field sowthistle has equal or higher in vitro digestible dry matter, micro- and macromineral content and crude protein and lower neutral detergent fiber compared to alfalfa [76]:

Nutritional values for field sowthistle [76].
Sample date	In vitro digestible dry matter concentration (g/kg)	Neutral detergent fiber concentration (g/kg)	Crude protein concentration (g/kg)
15 June 1981	818	312	164
29 June 1981	660	447	132
1 June 1982	792	267	214

Herbage macromineral and micromineral concentrations for field sowthistle are given in the following tables:

Herbage macromineral concentrations in g/kg [76].
Sample year	Ca	P	K	Mg
1981 (mean of 2 sample dates)	16.8	3.0	26.6	6.8
1982 (single sample date)	17.3	4.8	47.9	3.6

Herbage micromineral concentrations in µg/g [76].
Sample year	Zn	Cu	B	Mn	Al	Fe
1981 (mean of 2 sample dates)	22	10	26	63	393	334
1982 (single sample date)	40	10	26	53	83	108

Cover Value

Cover value of field sowthistle for several classes of wildlife for 2 western states is provided by Dittberner and Olson [32] in the following table:

State	Elk	Mule deer	White-tailed deer	Pronghorn	Upland game birds	Waterfowl	Small nongame birds	Small mammals
Utah	poor	poor	—	poor	fair	poor	poor	fair
North Dakota	—	good	good	fair	—	fair	—	—

Other Uses

Roasted roots of field sowthistle have been used like chicory (Cichorium intybus) root as an additive or a replacement for coffee. The young, tender leaves can be eaten raw in salads or cooked [118].

Most of the latex of field sowthistle is oil and may be a potential crop for oil or hydrocarbon production [19,20]. Field sowthistle is a good source of pentacyclic triterpenes, which may become important in the pharmaceutical industry [61].

Impacts

Information concerning the impacts of field sowthistle on natural communities is absent from the literature. Research is needed to determine and document what effects field sowthistle may have on wildlands.

Prevention

The most efficient and effective method of managing invasive species is to prevent their invasion and spread [107]. Since field sowthistle seed is so easily disseminated by wind, scouting and detection are keys to preventing plant establishment [133]. It is easier to prevent initial colonization by field sowthistle than to eliminate established populations. Seedlings are easily controlled through mechanical and chemical methods. Planting weed-free crop seed and controlling field sowthistle on field borders can prevent initial infestations in wildlands adjacent to agricultural settings [133] (See Seedling establishment/growth).

Control

Field sowthistle is relatively resistant to many common broadleaf herbicides compared to most annual broadleaf weeds. Consequently, the best systems for control often include a combination of cultural and chemical treatments designed to reduce competition from field sowthistle, prevent seed production, and reduce the reproductive capacity of its roots (Fryer and Makepeace, 1982, as reported in a literature review [74]).

As of this writing (2004) there is no information available on control of field sowthistle in natural areas.

Fire

See the Fire Management Considerations section of this summary.

Physical and Mechanical Control

Tillage generally reduces field sowthistle, but its effectiveness depends on plant growth characteristics at time of tillage [10,50,52], type of tillage being utilized [30,51], and frequency of tillage [92]. Intensive tillage is usually not appropriate in wildland settings, so it is not discussed further here.

Studies of mowing as a control method for field sowthistle show mixed results. Defoliation was less effective than burial for reducing infestations of field sowthistle in a study done in Sweden in 1967 [52], suggesting mowing is not as effective as tillage for control of field sowthistle [74]. However, Stevens [110] found defoliation an efficient method to control field sowthistle. Plants grown from root cuttings planted 3 May, had their leaves removed by hoe on 23 May when the largest leaves were about 6 inches (15 cm) long. The plants had the leaves removed again on 1 June, when leaves had again grown to about 6 inches (15 cm). After the 1 June defoliation, leaf growth was less vigorous. There was "very little" regrowth of leaves after a 1 July defoliation and none after a 19 July defoliation although weather conditions were favorable for growth. No plants appeared the next spring.

Biological Control

There appears to be limited biological agents available to help control field sowthistle. A tephritid fly from Europe that transforms the seedhead of field sowthistle into a gall has been released into Canada but has not become established [53]. Cystiphora sonchi, another fly native to Europe, was released into Canada and has become established in Alberta, Saskatchewan, Manitoba, and Nova Scotia [93]. Zollinger and Parker [133] report as many as 721 galls were formed on one plant of field sowthistle, but Lemna and Messersmith [74] state that no reduction in field sowthistle because of Cystiphora sonchi has been observed. A third fly, Liriomyza sonchi, has been authorized for release into Canada (Peschken and Derby 1988, reported in [74]).

Zollinger and Parker [133] provide a literature review of biological control efforts as of 1998.

Chemical Control

Auxin-type herbicides are the primary chemicals used to control field sowthistle. Field sowthistle is "moderately susceptible" to auxins such as 2,4-D, 2,4-DB, and MCPA in the seedling stage, and established stands are "moderately resistant" (Fryer and Makepeace, 1982, as reported in a literature review [74]). Growth of aerial portions can be retarded by auxin-type herbicides, and flowering can be completely suppressed if the plant is treated when growth is vigorous (Fryer and Makepeace 1982 as reported in a literature review [74]), and [77]. A more detailed discussion of chemical control of field sowthistle is provided by Lemna and Messersmith [74] and by Zollinger and Parker [133].

Integrated Management

Components of any integrated weed management program are sustained effort, constant evaluation, and the adoption of improved strategies [106]. Factors to be addressed before a management decision is made include inventory and assessment to identify the target weed(s) and determine the size of the infestation(s); assessment of nontarget vegetation, soil types, climatic conditions, and important water resources. An evaluation of the benefits and limitations of each control method also needs to be accomplished [84].

Combinations of tillage plus cultural practices or herbicides applied regularly have controlled field sowthistle in agricultural settings [30]. No information is available on integrated control measures for field sowthistle in wildlands.

Timing of control measures may increase the effectiveness of integrated management techniques. Schimming and Messersmith [102] conducted artificial freezing experiments with field sowthistle. They determined a temperature of 1 °F (-17 °C) reduced survival of field sowthistle roots by 50% and a temperature of 4 °F (-15 °C) reduced total dry weight of emerging field sowthistle shoots by 50%. The authors speculate conditions that tend to minimize hardening, such as lack of photosynthetic material in fall after tillage or chemical treatment, stimulation of fall growth after tillage, or high nitrogen levels may increase injury caused by freezing temperatures in the field.

Revegetation or Cultural Control

Patches of field sowthistle were cut for hay or were pastured as an early control measure [111,129]. An alfalfa or alfalfa-grass mixture, regularly cut for hay, can eliminate 90% of field sowthistle in 3 years (Martin and others 1961 in [74]).

"Intensive" grazing by domestic sheep or cattle weakens field sowthistle when the animals eat new growth and sometimes roots [133]. Grazing also enhances other control practices. However, field sowthistle is classified as an "increaser" under heavy grazing because it increases as more palatable plants are preferentially grazed [70].

Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.

Forest and Range Ecosystems (Garrison et al. 1977)

FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES27 Redwood
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES41 Wet grasslands
FRES42 Annual grasslands
FRES44 Alpine

BLM Physiographic Regions (Bernard and Brown 1977)

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

Kuchler Plant Associations (Kuchler 1964)

K001 Spruce-cedar-hemlock forest
K002 Cedar-hemlock-Douglas-fir forest
K003 Silver fir-Douglas-fir forest
K004 Fir-hemlock forest
K005 Mixed conifer forest
K006 Redwood forest
K007 Red fir forest
K008 Lodgepole pine-subalpine forest
K009 Pine-cypress forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K013 Cedar-hemlock-pine forest
K014 Grand fir-Douglas-fir forest
K015 Western spruce-fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine-Douglas-fir forest
K020 Spruce-fir-Douglas-fir forest
K021 Southwestern spruce-fir forest
K022 Great Basin pine forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodland
K025 Alder-ash forest
K026 Oregon oakwoods
K028 Mosaic of K002 and K026
K029 California mixed evergreen forest
K030 California oakwoods
K031 Oak-juniper woodland
K032 Transition between K031 and K037
K033 Chaparral
K034 Montane chaparral
K035 Coastal sagebrush
K036 Mosaic of K030 and K035
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K039 Blackbrush
K040 Saltbush-greasewood
K041 Creosote bush
K042 Creosote bush-bur sage
K043 Paloverde-cactus shrub
K044 Creosote bush-tarbush
K045 Ceniza shrub
K047 Fescue-oatgrass
K048 California steppe
K049 Tule marshes
K050 Fescue-wheatgrass
K051 Wheatgrass-bluegrass
K052 Alpine meadows and barren
K053 Grama-galleta steppe
K054 Grama-tobosa prairie
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
K057 Galleta-threeawn shrubsteppe
K058 Grama-tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
K060 Mesquite savanna
K061 Mesquite-acacia savanna
K062 Mesquite-live oak savanna
K063 Foothills prairie
K064 Grama-needlegrass-wheatgrass
K065 Grama-buffalo grass
K066 Wheatgrass-needlegrass
K067 Wheatgrass-bluestem-needlegrass
K068 Wheatgrass-grama-buffalo grass
K069 Bluestem-grama prairie
K070 Sandsage-bluestem prairie
K071 Shinnery
K072 Sea oats prairie
K073 Northern cordgrass prairie
K074 Bluestem prairie
K075 Nebraska Sandhills prairie
K076 Blackland prairie
K077 Bluestem-sacahuista prairie
K078 Southern cordgrass prairie
K081 Oak savanna
K082 Mosaic of K074 and K100
K083 Cedar glades
K084 Cross Timbers
K085 Mesquite-buffalo grass
K086 Juniper-oak savanna
K087 Mesquite-oak savanna
K088 Fayette prairie
K089 Black Belt
K090 Live oak-sea oats
K093 Great Lakes spruce-fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce-fir forest
K097 Southeastern spruce-fir forest
K098 Northern floodplain forest
K099 Maple-basswood forest
K100 Oak-hickory forest
K101 Elm-ash forest
K102 Beech-maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K107 Northern hardwoods-fir forest
K108 Northern hardwoods-spruce forest
K109 Transition between K104 and K106
K110 Northeastern oak-pine forest
K111 Oak-hickory-pine
K112 Southern mixed forest
K113 Southern floodplain forest
K114 Pocosin

SAF Cover Types (Eyre 1980)

1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce-tamarack
14 Northern pin oak
15 Red pine
16 Aspen
17 Pin cherry
18 Paper birch
19 Gray birch-red maple
20 White pine-northern red oak-red maple
21 Eastern white pine
22 White pine-hemlock
23 Eastern hemlock
24 Hemlock-yellow birch
25 Sugar maple-beech-yellow birch
26 Sugar maple-basswood
27 Sugar maple
28 Black cherry-maple
30 Red spruce-yellow birch
31 Red spruce-sugar maple-beech
32 Red spruce
33 Red spruce-balsam fir
34 Red spruce-Fraser fir
35 Paper birch-red spruce-balsam fir
37 Northern white-cedar
38 Tamarack
39 Black ash-American elm-red maple
40 Post oak-blackjack oak
42 Bur oak
43 Bear oak
44 Chestnut oak
45 Pitch pine
46 Eastern redcedar
50 Black locust
51 White pine-chestnut oak
52 White oak-black oak-northern red oak
53 White oak
55 Northern red oak
57 Yellow-poplar
58 Yellow-poplar-eastern hemlock
59 Yellow-poplar-white oak-northern red oak
60 Beech-sugar maple
61 River birch-sycamore
62 Silver maple-American elm
63 Cottonwood
64 Sassafras-persimmon
65 Pin oak-sweetgum
66 Ashe juniper-redberry (Pinchot) juniper
67 Mohrs (shin) oak
68 Mesquite
70 Longleaf pine
71 Longleaf pine-scrub oak
72 Southern scrub oak
73 Southern redcedar
74 Cabbage palmetto
75 Shortleaf pine
76 Shortleaf pine-oak
78 Virginia pine-oak
79 Virginia pine
80 Loblolly pine-shortleaf pine
81 Loblolly pine
82 Loblolly pine-hardwood
83 Longleaf pine-slash pine
84 Slash pine
85 Slash pine-hardwood
87 Sweetgum-yellow-poplar
88 Willow oak-water oak-diamondleaf (laurel) oak
89 Live oak
91 Swamp chestnut oak-cherrybark oak
92 Sweetgum-willow oak
93 Sugarberry-American elm-green ash
94 Sycamore-sweetgum-American elm
95 Black willow
96 Overcup oak-water hickory
97 Atlantic white-cedar
98 Pond pine
100 Pondcypress
101 Baldcypress
102 Baldcypress-tupelo
103 Water tupelo-swamp tupelo
104 Sweetbay-swamp tupelo-redbay
107 White spruce
108 Red maple
109 Hawthorn
110 Black oak
201 White spruce
202 White spruce-paper birch
203 Balsam poplar
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce-subalpine fir
207 Red fir
208 Whitebark pine
209 Bristlecone pine
210 Interior Douglas-fir
211 White fir
212 Western larch
213 Grand fir
215 Western white pine
216 Blue spruce
217 Aspen
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
221 Red alder
222 Black cottonwood-willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock-Sitka spruce
226 Coastal true fir-hemlock
227 Western redcedar-western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir-western hemlock
231 Port-Orford-cedar
232 Redwood
233 Oregon white oak
234 Douglas-fir-tanoak-Pacific madrone
235 Cottonwood-willow
236 Bur oak
237 Interior ponderosa pine
238 Western juniper
239 Pinyon-juniper
240 Arizona cypress
241 Western live oak
242 Mesquite
243 Sierra Nevada mixed conifer
244 Pacific ponderosa pine-Douglas-fir
245 Pacific ponderosa pine
246 California black oak
247 Jeffrey pine
248 Knobcone pine
249 Canyon live oak
250 Blue oak-foothills pine
251 White spruce-aspen
252 Paper birch
253 Black spruce-white spruce
254 Black spruce-paper birch
255 California coast live oak
256 California mixed subalpine

SRM Rangeland Cover Types (Shiflet 1994)

101 Bluebunch wheatgrass
102 Idaho fescue
103 Green fescue
104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
106 Bluegrass scabland
107 Western juniper/big sagebrush/bluebunch wheatgrass
108 Alpine Idaho fescue
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
201 Blue oak woodland
202 Coast live oak woodland
203 Riparian woodland
204 North coastal shrub
205 Coastal sage shrub
206 Chamise chaparral
207 Scrub oak mixed chaparral
208 Ceanothus mixed chaparral
209 Montane shrubland
210 Bitterbrush
211 Creosote bush scrub
212 Blackbush
213 Alpine grassland
214 Coastal prairie
215 Valley grassland
216 Montane meadows
217 Wetlands
301 Bluebunch wheatgrass-blue grama
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
304 Idaho fescue-bluebunch wheatgrass
305 Idaho fescue-Richardson needlegrass
306 Idaho fescue-slender wheatgrass
307 Idaho fescue-threadleaf sedge
308 Idaho fescue-tufted hairgrass
309 Idaho fescue-western wheatgrass
310 Needle-and-thread-blue grama
311 Rough fescue-bluebunch wheatgrass
312 Rough fescue-Idaho fescue
313 Tufted hairgrass-sedge
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
317 Bitterbrush-bluebunch wheatgrass
318 Bitterbrush-Idaho fescue
319 Bitterbrush-rough fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
323 Shrubby cinquefoil-rough fescue
324 Threetip sagebrush-Idaho fescue
401 Basin big sagebrush
402 Mountain big sagebrush
403 Wyoming big sagebrush
404 Threetip sagebrush
405 Black sagebrush
406 Low sagebrush
407 Stiff sagebrush
408 Other sagebrush types
409 Tall forb
410 Alpine rangeland
411 Aspen woodland
412 Juniper-pinyon woodland
413 Gambel oak
414 Salt desert shrub
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
417 Littleleaf mountain-mahogany
418 Bigtooth maple
419 Bittercherry
420 Snowbrush
421 Chokecherry-serviceberry-rose
422 Riparian
501 Saltbush-greasewood
502 Grama-galleta
503 Arizona chaparral
504 Juniper-pinyon pine woodland
505 Grama-tobosa shrub
506 Creosotebush-bursage
507 Palo verde-cactus
508 Creosotebush-tarbush
509 Transition between oak-juniper woodland and mahogany-oak association
601 Bluestem prairie
602 Bluestem-prairie sandreed
603 Prairie sandreed-needlegrass
604 Bluestem-grama prairie
605 Sandsage prairie
606 Wheatgrass-bluestem-needlegrass
607 Wheatgrass-needlegrass
608 Wheatgrass-grama-needlegrass
609 Wheatgrass-grama
610 Wheatgrass
611 Blue grama-buffalo grass
612 Sagebrush-grass
613 Fescue grassland
614 Crested wheatgrass
615 Wheatgrass-saltgrass-grama
701 Alkali sacaton-tobosagrass
702 Black grama-alkali sacaton
703 Black grama-sideoats grama
704 Blue grama-western wheatgrass
705 Blue grama-galleta
706 Blue grama-sideoats grama
707 Blue grama-sideoats grama-black grama
708 Bluestem-dropseed
709 Bluestem-grama
710 Bluestem prairie
711 Bluestem-sacahuista prairie
712 Galleta-alkali sacaton
713 Grama-muhly-threeawn
714 Grama-bluestem
715 Grama-buffalo grass
716 Grama-feathergrass
717 Little bluestem-Indiangrass-Texas wintergrass
718 Mesquite-grama
719 Mesquite-liveoak-seacoast bluestem
720 Sand bluestem-little bluestem (dunes)
721 Sand bluestem-little bluestem (plains)
722 Sand sagebrush-mixed prairie
723 Sea oats
724 Sideoats grama-New Mexico feathergrass-winterfat
725 Vine mesquite-alkali sacaton
726 Cordgrass
727 Mesquite-buffalo grass
728 Mesquite-granjeno-acacia
729 Mesquite
730 Sand shinnery oak
731 Cross timbers-Oklahoma
732 Cross timbers-Texas (little bluestem-post oak)
733 Juniper-oak
734 Mesquite-oak
735 Sideoats grama-sumac-juniper
801 Savanna
802 Missouri prairie
803 Missouri glades
804 Tall fescue
805 Riparian
806 Gulf Coast salt marsh
807 Gulf Coast fresh marsh

ALASKAN RANGELANDS

901 Alder
902 Alpine herb
903 Beach wildrye-mixed forb
904 Black spruce-lichen
905 Bluejoint reedgrass
906 Broadleaf forest
907 Dryas
908 Fescue
909 Freshwater marsh
910 Hairgrass
911 Lichen tundra
912 Low scrub shrub birch-ericaceous
913 Low scrub swamp
914 Mesic sedge-grass-herb meadow tundra
915 Mixed herb-herbaceous
916 Sedge-shrub tundra
917 Tall shrub swamp
918 Tussock tundra
919 Wet meadow tundra
920 White spruce-paper birch
921 Willow

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Last updated December 29, 2025

Sonchus arvensis, field sowthistle

Sonchus arvensis, field sowthistle

Citation

Species in This Review

Image Gallery

Introduction

Taxonomy

Synonyms

Other Common Names

Distribution

General Distribution

States and Provinces

Site Characteristics

Plant Communities

Botanical and Ecological Characteristics

Botanical Description

Raunkiaer Life Form

Seasonal Development

Regeneration Processes

Pollination and Breeding System

Seed Production

Seed Dispersal

Seed Banking

Germination

Seedling Establishment and Growth

Vegetative Reproduction and Regeneration

Successional Status

Fire Ecology and Management

Immediate Fire Effects

Postfire Regeneration Strategy

Fire Adaptations

Plant Response to Fire

Fire Regimes

Fire Management Considerations

Postfire Colonization Potential

Prescribed Fire as a Control Agent

Nonfire Management Considerations

Federal Status

Other Status

Importance to Wildlife and Livestock

Palatability and Nutritional Value

Cover Value

Other Uses

Impacts

Prevention

Control

Fire

Physical and Mechanical Control

Biological Control

Chemical Control

Integrated Management

Revegetation or Cultural Control

Appendix

References