Overview
Machaeranthera tanacetifolia is an annual wildflower of the Great Plains and southwestern United States growing 4–16 inches (10–40 cm) tall with branching, somewhat bristly stems. The daisy-like flower heads are 1.5–2 inches (4–5 cm) across, with 12–25 violet to purple ray florets surrounding a yellow central disc. The leaves are finely dissected into narrow toothed segments, giving a fern-like outline that resembles tansy foliage, 1–3 inches (2.5–7.5 cm) long. Flowering occurs from May to October, often heaviest after summer rain. The species grows in sandy and gravelly soils of plains, prairies, roadsides, and desert grassland from South Dakota and Wyoming south to Texas, Arizona, and northern Mexico. As an annual adapted to open, dry ground, it requires full sun and sharp drainage and is short-lived, completing its cycle in a single season and relying on seed to return. It establishes quickly on disturbed soil but does not compete well in dense or shaded plantings.
Native Range
Machaeranthera tanacetifolia is native to central and western North America, from South Dakota and Wyoming south through the Great Plains to Texas, New Mexico, Arizona, and northern Mexico. It grows in sandy prairies, gravelly plains, roadsides, and desert grassland.Suggested Uses
Used in wildflower meadows, dry sunny borders, and naturalized plantings on sandy soil. Sown in drifts and spaced 8–12 inches (20–30 cm) apart, it suits xeric and pollinator gardens.How to Identify
Appearance
Size & Dimensions
Height4" - 1'4"
Width/Spread6" - 1'
Bloom Information
Flowering extends from May to October, with the heaviest display following summer rains. Each head carries 12–25 violet to purple ray florets around a yellow disc. Plants bloom over a long season and set abundant seed that germinates the following year.
Detailed Descriptions
Flower Description
violet-purple with yellow centerFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Drought Tolerance
Drought tolerant when established
Care & Maintenance
Care Guide
Grow M. tanacetifolia in full sun in sandy, gravelly, or other sharply drained soil of low to moderate fertility. It withstands heat and drought and grows on dry plains and disturbed open ground. Soil pH from 6.5 to 8.0 suits it, including alkaline soils. As an annual, it is sown directly where it is to grow and relies on self-seeding to return. Overly rich or moist soil produces weak, leaning growth and reduced flowering. Plants establish rapidly from spring-sown seed.Pruning
No pruning is required. Light shearing after the first flush of bloom can prompt a further round of flowers. As an annual, the plant dies after setting seed and can be left to self-sow.✓ Toxicity
Non-toxicPlanting Guide
Planting Methods & Timing
Planting Method
direct sow
Direct Sow Timing
Spring after the last frost, or fall in mild-winter regions
Plant Spacing
10 inches