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Thelesperma spp.
Greenthread
Americas, centered on the Great Plains and Mexico
Overview
Thelesperma spp. is a genus of about a dozen annual and perennial herbs in the daisy family, native to open, dry grasslands of the Americas, with the greatest concentration in the central and southwestern United States and Mexico. Plants form slender, branching clumps 12-30 inches (30-75 cm) tall, with finely divided, thread-like leaves that give the genus its common name, greenthread. Long, wiry stalks carry daisy-like flower heads with yellow ray florets around a darker central disk; some species, such as T. megapotamicum, are rayless, with brownish-yellow disk flowers only. The dried foliage and flowers of several species are steeped as a traditional beverage known as Hopi or Navajo tea. Plants grow on sandy, rocky, and clay soils, including alkaline ground, and tolerate heat and drought once established. They are short-lived in rich, moist soil and self-seed freely, sometimes spreading into nearby beds. Most perennial species die back to a crown in winter and regrow in spring, while annual species complete their cycle in a single season. Flowering runs through the warm months.
Native Range
Thelesperma spp. is native to the Americas, centered on the Great Plains and southwestern United States and Mexico, with some species in South America. It grows on prairies, plains, roadsides, and dry, open ground.Suggested Uses
Used in prairie and meadow plantings, wildflower gardens, and dry borders, and grown for traditional herbal tea. Suited to hot, sunny, low-water sites with sharp drainage.How to Identify
Appearance
Size & Dimensions
Height1' - 2'6"
Width/Spread10" - 1'6"
Reaches mature size in approximately 1 years
Bloom Information
Detailed Descriptions
Flower Description
yellow, sometimes with brown-redFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-10 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
Care & Maintenance
Care Guide
Grow in full sun on light, sharply drained sandy, rocky, or clay soil, including alkaline ground. Water occasionally until established, then rely on rainfall, as plants tolerate heat and drought. Rich, wet soil shortens their life and causes flopping. Cut back after the main bloom to tidy plants and limit self-seeding. Perennial species are hardy to USDA zone 4 and regrow from the crown each spring.Pruning
Shear or cut back spent flower stems after the main flush to encourage rebloom and limit self-seeding. Remove dead growth in late winter before new shoots appear. No other pruning is needed.Container Growing
✓ Suitable for container growing
Minimum container size: 2 gallons