Paperflowers

Psilostrophe tagetina, P. gnaphaloides

Asteraceae (Sunflower Family)

Description

There are two species of paperflower in Texas. Woolly or hairy paperflower (P. tagetina) is similar to cudweed paperflower (P. gnaphaloides) in foliage, manner of growth and general appearance, but usually is much woollier. Both species affect livestock the same way. Paperflowers are erect, perennial herbs of the sunflower family. Stems and leaves are thinly hairy. Leaves are alternate and narrow, and generally decrease in size as they move upward on the plant. Lower leaves form a rosette at the plant base. Plants flower continuously from spring through first frost. Flower heads are yellow, occurring in loose to dense clusters at branch ends. The flower petals become pale and papery with age, hence the name paperflower.

Habitat

Paperflowers are typically found on open, dry ranges in semiarid regions of Texas, Utah, New Mexico, Arizona and Mexico. Both species are very common in western Texas.

Toxic Agent

The toxic agent is a sesquiterpene lactone. The plant is more toxic in the young, green stage than after maturity. In most cases, paperflowers are considered poisonous only to sheep, although cattle may be susceptible.

Signs of Livestock Ingestion

Paperflowers are relatively palatable to sheep, which can graze the plant for up to 2 weeks before poisoning signs appear. Signs from paperflower toxicity include: General discomfort and uneasiness; Weakness of the hind legs; Regurgitation of food or greenish liquid.

At first, sheep may appear in good condition, but show some incoordination and stumbling when running. Later they become sluggish, lose their appetite and cough violently, causing them to regurgitate a greenish liquid.

Eventually they become depressed and emaciated and die after a week or more of partial coma.

Management Strategies

No livestock treatment is specified for paperflower poisoning, although most animals recover completely if moved to a noninfested pasture or put on feed as soon as signs appear. To minimize paperflower consumption, supplement the diet with a high-quality protein. Because paperflower can be grazed for about 2 weeks before signs occur, manage grazing to reduce plant density by placing many animals on pastures for short periods. Rotate grazing between infested and noninfested pastures to help control losses. Another successful strategy is to graze the pasture first with cattle only, then allow access by sheep after the paperflower has matured.