Threadleaf ragwort

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Threadleaf ragwort

Threadleaf ragwort

Threadleaf ragwort heads

Threadleaf ragwort

Threadleaf ragwort leaves

Threadleaf ragwort leaves

Morphology

Stem

Shrubs; stems spreading to ascending.Twigs light green to grayish green, flexible, lanate to tomentose, sometimes unevenly glabrescent, striate; leaf scars shallowly crescent-shaped; buds white, lanate.Trunk bark tan to brown, fissures shallow, ridges flat, exfoliating in small plates.

Leaves

Alternate, simple; petiole 0 to .08 inch; blade linear to lanceolate or ovate (when lobed), 1.2 to 4.8 inches long, .2 to 2 inches wide, base truncate, margins entire or pinnatifid, lobes linear, apex acute to acuminate, surfaces dark green to grayish green, lanate to tomentose, sometimes unevenly glabrescent.

Inflorescence

Terminal on new growth, heads in corymb-like arrays, .8 to 3.2 inches long, .4 to 2.4 inches wide; involucres cylindric or top-shaped to bell-shaped, .3 to .5 inch; phyllaries mostly 8, 13, or 21, in 1-2 series, lanceolate to linear, .25 to .5 inch long, .03 to .06 wide, sparsely lanate proximally.

Flower

Ray florets pistillate, usually 8 or 13, rarely 21; corolla yellow or yellowish white, ligule .4 to .6 inch1; pistil 1, style 1; stigmas 2; disk florets bisexual, 10-80; corolla yellow, tubular, .25 to .35 inch, 5-lobed; stamens 5.

Fruit

Fruits August-September; achenes, brown, cylindric to compressed-ellipsoid, .12 to .14 inch long, hirtellous, obscurely 5-ribbed; pappus of 30-80 hairlike bristles, +/- connate basally, white, .2 to .3 inch; seed 1.

Ecology

Habitat

Sandy to gravelly shortgrass prairies, rocky slopes.

Distribution

South half of west 1/5 of Kansas.

Practical Information

Toxicity

Senecio flaccidus is poisonous to livestock, as are many other species of Senecio.

Uses

Several western North American Indian tribes used threadleaf ragwort medicinally, primarily externally in the form of a poultice.