BugwoodWiki Article

common cocklebur
Xanthium strumarium L.

Overview

Appearance
Xanthium strumarium is an annual that produces a conspicuous prickly 'cocklebur' and ranges from 0.5-6.5 ft. (0.2-2 m) in height. The relatively large, linear to oblong waxy cotyledons helps to distinguish this weed in the early stages of development.
Foliage
The first true leaves are opposite, all subsequent leaves are alternate. Leaves are triangular to ovate in outline, have stiff hairs, and are approximately 2-6 in. (5.1-15.2 cm) long. Leaves are irregularly lobed with leaf margins that have relatively inconspicuous teeth.
Flowers
Inconspicuous, greenish in color, arising from the area between the leaf petioles and the stems and at the ends of the erect stems.
Fruit
An elliptic to egg-shaped two-chambered bur, 0.5-1.5 in. (1.3-3.8 cm) long and covered with hooked prickles. Each bur contains two seeds, one that grows during the first year and one that grows a year later. Two prickles that are longer and wider than the remaining prickles project from the tip of the bur.
Ecological Threat
Xanthium strumarium is found throughout the United States and is primarily a weed of agronomic and horticultural crops, nurseries, and occasionally pastures.

General Description:

Xanthium strumarium is a coarse annual herb. The name Xanthium is derived from the Greek XANTHOS, meaning yellow, from the ancient name of some plant, the fruit of which was used to dye the hair that color.

Many specific epithets have been applied to Xanthium strumarium, including: orientale, canadense, chinense, occidentale, macrocarpum, longirostre, pennsylvanicum, and oviforme. The consensus of taxonomic opinion follows Love and Dansereau's (1959) suggestion that these "species" are actually subspecies or varieties of this highly variable weed. They suggest that X. strumarium consists of seven complexes: strumarium, cavanillesii, oviforme, echinatum, chinense, hybrid, and orientale. There is no evidence of any sterility barriers separating the entities of X. strumarium, but intense inbreeding with occasional outbreeding is responsible for the enormous variation which often results in small, local, but unstable taxa. At least seven varieties or subspecies have been described from California, but today these are generally considered part of the cavanillesii (pennsylvanicum) morphological complex. However, McMillan (1975) considers this a separate species, X. californicum Greene.

Diagnostic Characteristics

Xanthium strumarium is distinguished from spiny clotbur (X. spinosum) by its broader cockleburs, more ovoid leaves on long petioles, and lack of spines.

STEWARDSHIP SUMMARY

Xanthium strumarium is a common annual weed spread by water, humans, or other animals. Its origin is still being debated, but cocklebur may be a native California species. It is most abundant on moist open sites but is present on a variety of waste places. Cocklebur is toxic to certain animals. It reproduces from seeds that are viable for up to several years. Biological control measures are currently being investigated and may prove effective in the future. Simple mechanical removal prior to flowering is recommended for control. If pulled following flowering, the plants should be burned. Monitoring should be continued on the sites for several years.

NATURAL HISTORY

Range

Xanthium strumarium is distributed worldwide (53 degrees north to 33 degrees south latitude) but is most common in the temperate zone. It is a serious weed in Australia, India, South Africa, and the Americas.

There has been considerable controversy regarding the origin of cocklebur. Though first described from Europe, it is probably of American origin. Love and Dansereau (1959) suggest that the cocklebur subspecies most abundant in North America (cavanillesii) originated in Central America. The dates of its introduction to California are not known, but it may be pre-Columbian.

Habitat

Cocklebur is often associated with open, disturbed areas, particularly flood-prone areas with good soil moisture, but it is found in a wide variety of habitats. It frequents roadsides, railway banks, small streams, and riverbanks, as well as the edges of ponds and freshwater marshes and overgrazed pastures. It does not tolerate shading.

Cocklebur grows on a wide range of soils (sands to heavy clays) and available moisture. On rich soils with abundant moisture and little competition from other plants, it grows tall and luxuriant, forming pure stands. In dry, poor soils, plants may grow to only a few centimeters high, persist through drought, and set seed. The ability to grow under a variety of conditions results in a continuous seed supply, if plants are not controlled.

Cocklebur withstands partial submergence for six to eight weeks by forming adventitious roots from the submerged portion of the stem. These roots float in water and often get infested with oxygen-producing green algae (Dedogonium) which solves the problem of aeration.

Resources

Selected Images


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common cocklebur
Xanthium strumarium
Fruit(s)
Jan Samanek
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common cocklebur
Xanthium strumarium
Fruit(s)
Steve Dewey
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common cocklebur
Xanthium strumarium
Fruit(s)
Jan Samanek
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common cocklebur
Xanthium strumarium
Stem(s)
Rebekah D. Wallace
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common cocklebur
Xanthium strumarium
Plant(s)
Bruce Ackley
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common cocklebur
Xanthium strumarium
Seedling(s)
John D. Byrd
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common cocklebur
Xanthium strumarium
Fruit(s)
David J. Moorhead
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common cocklebur
Xanthium strumarium
Foliage
Bruce Ackley
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common cocklebur
Xanthium strumarium
Fruit(s)
Jan Samanek
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common cocklebur
Xanthium strumarium
Plant(s)
Jan Samanek
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common cocklebur
Xanthium strumarium
Feature(s)
Forest and Kim Starr
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common cocklebur
Xanthium strumarium
Seed(s)
Steve Hurst
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common cocklebur
Xanthium strumarium
Plant(s)
Jan Samanek
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common cocklebur
Xanthium strumarium
Infestation
David J. Moorhead
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common cocklebur
Xanthium strumarium
Foliage
David J. Moorhead
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common cocklebur
Xanthium strumarium
Plant(s)
USDA PLANTS Database
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common cocklebur
Xanthium strumarium
Seed(s)
Jan Samanek
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common cocklebur
Xanthium strumarium
Fruit(s)
D. Walters and C. Southwick
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common cocklebur
Xanthium strumarium
Fruit(s)
D. Walters and C. Southwick

Maps


EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org

EDDMapS Distribution

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit Invasive.org

State Regulated List

Most Troublesome / Most Common Agricultural Weed List
This map identifies those states that consider this species either most troublesome or most common in at least one commodity. For more information, visit the MTMC project page.

State Regulated List
Legend
   No Data for this state
   Troublesome or Common weed in one or more crops

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Asteridae
Order: Asterales
Family: Asteraceae
Genus: Xanthium

Other System Links

Plants: XAST
Bayer: XANST
GRIN: 42072
ITIS: 38692
NPDN Host: 36501

Synonyms and Other Names

Other Common Names:
cocklebur, cockleburr, rough cocklebur

Categories

Category: Forbs/Herbs