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Spiny bear's breeches

Meneerke bloem / Wikimedia Commons - CC BY-SA 3.0

Spiny bear's breeches

Acanthus spinosus

Spiny bear's breeches (Acanthus spinosus) is a bold architectural perennial of southeastern Europe and the southern Balkans, grown for its foliage as much as its flowers. It builds a mound of deeply cut, arching, glossy dark-green leaves to about 24 to 35 inches long, and those leaves are the point of difference from the commoner Acanthus mollis: they are far more finely divided and carry rigid spines at the lobe tips, so the plant is thistle-like to the touch rather than soft. In early to midsummer it sends up stiff spikes to about 3 to 4 feet, set in vertical rows of pure white hooded flowers under spiny reddish-purple bracts. It is generally rated the freer and more reliable flowerer of the two garden species and holds the RHS Award of Garden Merit. The honest catch is the same as A. mollis: deep, fleshy, brittle roots that spread by creeping rootstock and regenerate from fragments, so an established plant is slow and difficult to move or remove, and the leaf spines make digging it out an unpleasant job. Site it as a long-term decision.

Climate fit: narrow (39/100)

Focal point

Border

Structure

Light

Full sun / Part shade

Water

Moderate water

Mature size

3-4 ft tall · 30" apart

Hardy in zones

5a-9b

very cold to frosty winters

Native in Illinois

No

Related products

Cold hardiness

These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.

Now

Zone 6b

Plotwright

USDA Zone 6b

-5°F to 0°F

Well-suited

2050

2100

Zone 7a

Plotwright

0°F to 5°F

Well-suited

In plain terms: This location has cold winters. Its winters are projected to keep warming through 2050.

✓

Well-suited today and still thriving in 2050.

Heat tolerance

Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.

Loading AHS heat-zone data for this location...

Where this plant fits

Suitable across 40 ecoregions - 31 climate-resilient through 2070 · 1 suited today · 8 newly possible by 2070. Best matches first.

Appalachian mixed mesophytic forests

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Appalachian-Blue Ridge forests

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Arizona Mountains forests

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Atlantic coastal pine barrens

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Blue Mountains forests

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Central Pacific Northwest coastal forests

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Central-Southern Cascades Forests

Colorado Rockies forests

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Educator packet

Plant packet

Spiny bear's breeches educator packet

Spiny bear's breeches (Acanthus spinosus) is a bold architectural perennial of southeastern Europe and the southern Balkans, grown for its foliage as much as its flowers. It builds a mound of deeply cut, arching, glossy dark-green leaves to about 24 to 35 inches long, and those leaves are the point of difference from the commoner Acanthus mollis: they are far more finely divided and carry rigid spines at the lobe tips, so the plant is thistle-like to the touch rather than soft. In early to midsummer it sends up stiff spikes to about 3 to 4 feet, set in vertical rows of pure white hooded flowers under spiny reddish-purple bracts. It is generally rated the freer and more reliable flowerer of the two garden species and holds the RHS Award of Garden Merit. The honest catch is the same as A. mollis: deep, fleshy, brittle roots that spread by creeping rootstock and regenerate from fragments, so an established plant is slow and difficult to move or remove, and the leaf spines make digging it out an unpleasant job. Site it as a long-term decision.

Scientific name

Acanthus spinosus

Plant type

perennial

Hardiness

5a-9b

Light

full-sun, part-shade

Moisture

moderate

Spacing

30 inches

Classroom prompts

- Which plant traits are observations, and which are care recommendations?

- How would this plant fit change if the garden location moved warmer, colder, wetter, or drier?

- Which source-backed facts would you cite in a lesson handout?

Use the Sources & citations section below for page citation styles and the field-level source list.

Sources & citations

Cite this page

For lesson plans, articles, or research that uses this page. Use the source cards below to explore the references that informed this record.

Plotwright. (2026, May 17). Spiny bear's breeches (Acanthus spinosus). Retrieved 2026, August 27, from https://plotwright.com/plants/acanthus-spinosus

Sources used for this record

This record is compiled from the sources below.

Plants of the World Online (POWO)

Botanical research database

Open source

Source guide

RHS Find a Plant

Botanical research database

Open source

Source guide

Missouri Botanical Garden PlantFinder

Botanical research database