Common kochia (Kochia scoparia)

Synonyms: Bassia scoparia, Bassia sieversiana, Chenopodium scoparium, Atriplex scoparia

Common Names: Kochia, summer cypress, Mexican fireweed, burningbush, mock cypress, fireball, belvedere

Description:

Common kochia (Kochia scoparia, now also classified as Bassia scoparia) is a fast-growing annual in the amaranth family, native to Europe and Asia and introduced to North America as an ornamental and forage plant [1][2][3]. It is now a widespread weed of disturbed and dry ground ? especially rangelands, crop fields, roadsides, and waste areas ? and is one of the "tumbleweeds" that break off and roll in the wind to scatter seed [1][2]. MISIN tracks it because it seeds heavily, tolerates drought and salty soils, can poison livestock, and has become hard to control where it has built up resistance to herbicides [1].

Habit:

Common kochia is a bushy summer annual that grows into a rounded or pyramid-shaped plant, often a few feet tall but sometimes reaching 6 feet or more [1]. Its leaves are alternate, narrow and lance-shaped to nearly linear, about ? to 2? inches long, soft, and covered with fine hairs, often fringed with longer hairs along the edges [1][2]. The stems are highly branched and finely ribbed, green when young and often turning red or red-striped as the plant ages [1][2]. The flowers are tiny, green, and petal-less, tucked in the leaf joints and stem tips, easy to overlook [1][2]. As autumn comes the whole plant dries, breaks off at the base, and tumbles in the wind ? scattering seed as it goes [1][2].

It is easiest to spot from midsummer into fall (about July through October), when the plants are full-sized bushes and begin turning red, and again as dried tumbleweeds in late fall and winter [1][2]. In spring, look for seedlings forming a low, gray-green, hairy mat on bare, disturbed ground [1].

At-a-glance cues:

1. Bushy, much-branched annual forming a rounded or pyramid-shaped plant, often turning red with age [1][2]
2. Narrow, soft, hairy, lance-shaped leaves fringed with hairs along the edges [1][2]
3. Finely ribbed green-to-red stems; tiny green petal-less flowers in the leaf joints [1][2]
4. At maturity the dried plant breaks off at the base and tumbles in the wind [1][2]

Leaves:

1. Arrangement: alternate along the stem [1][2]
2. Shape: narrow, lance-shaped to nearly linear, about ? to 2? inches long [1][2]
3. Margin: smooth (entire), fringed with fine hairs [1]
4. Veins: with 1?5 prominent lengthwise veins [2]
5. Surface: soft and hairy, gray-green, especially when young [1]

Stems:

1. Habit: an erect, much-branched summer annual forming a rounded or pyramid-shaped bush, from about 1 foot to 6 feet or more tall, with a taproot [1][2]
2. Surface: finely ribbed, hairless to sparsely hairy [2]
3. Color: green when young, often turning red or red-striped with age [1][2]

Flowers:

1. Color: green, petal-less, inconspicuous, backed by small leaf-like bracts with tufts of hair [1][2]
2. Arrangement: tiny flowers, single or clustered, in the upper leaf joints and in spike-like clusters at the stem tips [1][2]
3. Bloom time: midsummer into fall, about July through October [2]

Fruit and seeds:

1. Fruit type: a tiny dry fruit (utricle) enclosed in a papery shell, sometimes with a small membranous wing [1][2]
2. Seeds: small (about 1/10 inch), egg-shaped, dull brown to black, with a bumpy, grooved surface [1]
3. Output: extremely high ? a single plant can produce roughly 15,000 to 25,000 or more seeds [1]
4. Dispersal: the whole dried plant breaks off and tumbles in the wind, scattering seed widely; seed also moves in soil, water, and on equipment [1][2]

Habitat:

Common kochia is native to Europe and Asia and was introduced to North America, where it has spread widely ? it is especially common across the western states and Great Plains and occurs on disturbed ground elsewhere, including the Midwest [1][2]. It is a plant of open, disturbed, and often harsh sites rather than shaded natural habitat [1][2].

It thrives in full sun on dry, disturbed soils and tolerates drought, heat, and salty soils that many plants cannot [1][2]. Look for it on rangelands and pastures, crop fields, roadsides, railroad edges, ditch banks, feedlots, vacant lots, and other waste places [1][2].

Reproduction:

Common kochia spreads entirely by seed, and it is a champion seeder ? a single plant can produce 15,000 to 25,000 or more seeds [1]. Its signature trick is tumbleweed dispersal: when the plant dries in fall it snaps off at the base and rolls across open ground in the wind, dropping seed over a long distance as it tumbles [1][2]. Seed also travels in soil, in water along ditches, in hay and feed, and on vehicles and equipment, so the plant readily reaches new disturbed ground [1].

It is a summer annual. Seedlings emerge over a long stretch ? often starting in early spring and continuing into late summer ? then the plants grow fast, flower from midsummer into fall, set seed, and die [1][2]. For control, the key is to stop seed: remove or cut plants before the flowers mature into seed, and target spring and early-summer seedlings before they get large [1].

Impact and Damage:

For homeowners and anyone with livestock, the most important thing to know is that common kochia can be poisonous to grazing animals. The plant builds up nitrates, oxalates, and other compounds that can sicken or kill cattle and sheep when eaten in quantity, and the risk rises as the plant matures or is stressed by drought [1]. Its pollen is also a known hay-fever allergen [1]. In yards and small acreages it is a fast, bushy weed that crowds gardens and bare ground and becomes a nuisance tumbleweed that piles against fences and buildings in fall [1][2].

For natural area stewards and growers, common kochia is a serious weed of agriculture and rangeland across the western and central United States [1][2]. It competes strongly with crops and pasture for water and nutrients, especially on dry and salty soils, and its heavy seeding and tumbleweed spread let it move quickly across disturbed landscapes [1][2]. It has also become much harder to control because some kochia populations have developed resistance to widely used herbicides, including glyphosate [1]. Because it favors disturbed, open ground, the most effective response is to keep soil covered and stop plants from setting seed [1].

Similar species:

Common kochia grows alongside several other weeds of disturbed ground and is easily confused with them, especially as a seedling. Its surest marks are its soft, hairy, narrow leaves with no spines and no white mealy coating, and its habit of drying into a tumbleweed [1][2].

Russian thistle (Salsola tragus) is the classic tumbleweed and is often mistaken for kochia because both dry up and roll in the wind. It is told apart by its stiff, spine-tipped leaves and bracts, which feel prickly, while kochia's leaves are soft and hairy with no spines [1][2].

Common lambsquarters (Chenopodium album) is a related weed of gardens and fields with a similar upright, branching shape. It is distinguished by the white, mealy, powdery coating on its young leaves and stem tips, which kochia lacks ? kochia's leaves are hairy rather than mealy [2].

Redroot pigweed (Amaranthus retroflexus) is another weedy relative of disturbed ground. It is separated by its broader, oval leaves and dense, bristly flower clusters, unlike kochia's narrow, soft, hairy leaves and tiny, inconspicuous flowers [2].

Monitoring and rapid response:

Signs to watch for:

1. A low, gray-green, hairy seedling mat on bare disturbed ground in spring [1]
2. Bushy, much-branched plants with narrow, soft, hairy leaves, often turning red, midsummer into fall [1][2]
3. Dried plants breaking off at the base and tumbling in the wind in late fall ? a sign seed is being scattered [1][2]

What you can do:

1. Pull or hoe young plants in spring and early summer, while they are small and the soil is moist, before they set seed [1]
2. Cut or mow plants low before the flowers mature into seed, and bag and remove plants that are flowering or seeding rather than composting them [1]
3. Keep bare ground mulched, planted, or otherwise covered so seedlings have less open soil to colonize, and clean seed and soil off equipment [1]
4. Catch and remove tumbleweeds before or as they break loose in fall so they cannot roll and spread seed across a property [1][2]
5. For rangeland, field edges, and natural areas, crews can prioritize stopping seed production across a site and target new and outlying patches first, repeating over several seasons to draw down the seed in the soil [1]

When to call a professional:

1. Large infestations across pastures, crop fields, or rangeland where hand and mechanical removal cannot keep up [1]
2. Populations that keep returning despite removal, or that are suspected of resisting common herbicides [1]
3. Where livestock may graze kochia, consult a veterinarian or extension office about poisoning risk before relying on grazing [1]
4. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Colorado State University Extension. Identification and Management of Kochia and Russian Thistle. extension.colostate.edu
2. Minnesota Wildflowers. Bassia scoparia (Summer Cypress / Kochia). minnesotawildflowers.info
3. Plants of the World Online (POWO), Royal Botanic Gardens, Kew. Bassia scoparia (L.) Voss (syn. Kochia scoparia). powo.science.kew.org

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