How much sun does California-bur need?

California-bur grows best in full sun conditions.

When does California-bur bloom?

California-bur blooms in July, August, and September.

Where is California-bur native?

California-bur (Xanthium strumarium) is native to AL, AR, CA, CO and 40 more states, per vouchered herbarium specimen records and regional native plant society lists.

Is California-bur toxic to cats?

Yes. California-bur is listed as toxic to cats by the Cornell University Poisonous Plants Database (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.

What pollinators does California-bur attract?

California-bur draws bees and beetles.

Is California-bur HOA-friendly?

California-bur takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

California-bur

Name: Pollinator Patch
Author: Pollinator Patch

Xanthium strumarium

Last reviewed: August 2026

Toxicity unknown

California-bur (Xanthium strumarium) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

full sun

Water

medium

Size

12"–48" H × 12"–36" W

Bloom

Jul, Aug, Sep

Native to

AL, AR, CA, CO and 40 more states

Pollinators

bees, beetles

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.

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Browse plants for this ecoregion

Coast Range Marine West Coast Forest Sierra Nevada Central California Foothills and Coastal Mountains Central California Valley Southern California Mountains Northwestern Forested Mountains North American Deserts Central Basin and Range Mojave Basin and Range Southern Rockies Arizona/New Mexico Mountains Chihuahuan Deserts High Plains Southwestern Tablelands Central Great Plains Great Plains Cross Timbers Edwards Plateau East Central Texas Plains Western Gulf Coastal Plain South Central Plains Eastern Temperate Forests Ozark Highlands Central Irregular Plains Northwestern Glaciated Plains Northwestern Great Plains Piedmont Northern Glaciated Plains Western Corn Belt Plains Northern Forests Northern Lakes and Forests North Central Hardwood Forests Driftless Area Southeastern Wisconsin Till Plains Central Corn Belt Plains Eastern Corn Belt Plains Southern Michigan/Northern Indiana Drift Plains Huron/Erie Lake Plains Northeastern Highlands Northeastern Coastal Zone Northern Allegheny Plateau Erie Drift Plain Middle Atlantic Coastal Plain Northern Piedmont Southeastern Plains Blue Ridge Ridge and Valley Central Appalachians Western Allegheny Plateau Interior Plateau Interior River Valleys and Hills Mississippi Alluvial Plain Mississippi Valley Loess Plains Southern Coastal Plain Madrean Archipelago Sonoran Basin and Range Eastern Great Lakes Lowlands Atlantic Coastal Pine Barrens Southern California/Northern Baja Coast

A sturdy annual forb that grows 1-4 feet tall with broad leaves and small greenish flowers from July through September. This plant produces distinctive spiny seed pods that can stick to clothing and animal fur. It thrives in full sun with average moisture and establishes quickly from seed.

In an HOA neighborhood

California-bur takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.

Classified as noxious weed
Produces painful spiny burrs
Looks extremely weedy and unkempt

Wildlife value

The summer flowers attract bees and beetles for pollination. The seeds provide food for birds and small mammals.

Common questions

How much sun does California-bur need?: California-bur grows best in full sun conditions.
When does California-bur bloom?: California-bur blooms in July, August, and September.
Where is California-bur native?: California-bur (Xanthium strumarium) is native to AL, AR, CA, CO and 40 more states, per vouchered herbarium specimen records and regional native plant society lists.
Is California-bur toxic to cats?: Yes. California-bur is listed as toxic to cats by the Cornell University Poisonous Plants Database (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
What pollinators does California-bur attract?: California-bur draws bees and beetles.
Is California-bur HOA-friendly?: California-bur takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

See all plant problem guides

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