Ten-petal Blazingstar
Mentzelia decapetala
Ten-petal Blazingstar (Mentzelia decapetala) is a native biennial with rough, wavy-edged leaves and large white to cream flowers that have ten petals around a mass of yellow stamens. It blooms July into September on roadsides and dry slopes, scattered across South Dakota, including the Black Hills, and the flowers open in late afternoon and close around midnight. Photographed in the Black Hills.
| Family | Loasaceae · Stickleaf |
|---|---|
| Status | Native biennial |
| Blooms | July into September |
| Height | 40–100 cm (16–39 in) |
| Where | Roadsides, dry rocky slopes and other disturbed ground |
| Also called | Ten-petal Mentzelia, Chalk Lily, Evening Starflower, Candleflower, Ten-petal Stickleaf |
| Toxicity | It accumulates selenium and can be mildly poisonous. |
Roots, seeds & germination
Root: A strong, deep taproot. Plants do not survive transplanting.
Seed: A cylindrical capsule, 3–5 cm long, holds many flat seeds with a thin wing, 3–5 mm long. Birds eat the seeds.
Germination: Seed has little dormancy and can be sown in fall or spring. Collect in September and October, when pods are brown.
How do you identify Ten-petal Blazingstar?
Look for flowers with ten white to cream petals, each 5–7 cm long and often overlapping, around 200 to 300 yellow stamens. They open late in the day and fade by night. The lower stem has whitish bark that peels off, and the rough leaves have clinging hairs that stick a little.
When does it bloom?
July into September.
Where does it grow?
Roadsides and other disturbed places, dry rocky hillsides, steep banks and shale slopes, in well-drained, poor soil. It does poorly in rich soil.
Other flowers to compare
Sources: SDSU Open PRAIRIE: Mentzelia decapetala; Kansas Wildflowers: Ten-petal mentzelia; Boulder County Open Space: Ten-petal Stickleaf, Plant of the Month; National Park Service, Devils Tower: Wildflowers; Plant Story: Handsome Ten-petal Blazingstar (khkeeler.blogspot.com).