Grindelia squarrosa aka Curly Cup Gumweed

Grindelia squarrosa is a wildflower in the daisy family. It has lots of resin, a sticky substance. Its names include curlycup gumweed, tarweed, and rosinweed. Kew gives its native range as southeastern Colorado to southwestern Kansas. This range also takes in northwestern and central Texas. Other records show it grows more widely in North America. It grows on prairies, plains, and dry banks. It also grows on ground that people have disturbed.

Sources differ on how long it lives. Kew lists an annual or subshrub. An annual lives one year; a subshrub has a woody base. Plants For A Future calls it a biennial or perennial. These plants live two years or more than two years. That source gives a height of 3 feet (0.9 metres). Its spread reaches about 3.3 feet (1 metre). It grows fast, but each plant may have a short life. A planting may need new seedlings to keep growing. Its coarse leaves may look out of place in formal beds.

Bright yellow flower heads bloom from July to September. Green bracts, or leaf-like parts, bend back sharply around each head. Sticky resin coats them and gives gumweed its name. The resin is white or clear. The leaves and flower heads hold bitter, harsh compounds. Each flower has both male and female organs. Insects pollinate the blooms, which give them late-season food. Some birds and small mammals eat the seeds. The stems give them cover and places to perch.

Grow this plant in full sun and well-drained soil. It suits sand or loam, even soil with few nutrients. It grows in slightly acid, neutral, or slightly alkaline soil. The soil may be dry or moist. Once plants take root, they can cope with drought. Plants For A Future lists USDA zones 3–9. Its long bloom season suits prairie gardens and natural-style beds. Uses also include roadside planting and work to restore habitats. Strips grown to feed pollinators can include it too. It can become weedy, so think about its self-seeding.

The flower heads can yield yellow and green dyes. Indigenous peoples of North America used gumweed for chest and skin problems. It also has a history of use in herbal medicine. These uses do not make it a safe food. People have chewed or steeped the leaves and flower heads. Their bitter resin can cause irritation. Do not eat or drink them as a routine. The plant may build up selenium; the source also reports safrole. People with heart or kidney problems should not use it as an herb. Seek trained guidance for any use as medicine. Do not try home treatments on your own.