Herbage minutely hispidulous to hirtellous or sparsely puberulous (at least distal stems), not resinous. Leaf blades oblong-oblanceolate, 20-35 mm, margins pinnatifid (lobes spreading at right angles, linear to filiform). Involucres 4-6.5 × 2-2.8 mm. Phyllary apices with small, sharply delimited, green resinous area, not aristate, often distinctly thickened and approaching resin pockets, usually gland-dotted. Florets 8-12(-15); corollas 4.5-6 mm. Cypsela ribs not forming hornlike extensions.

Flowering Sep-Nov. Sandy or gravelly flats and hills, grasslands, usually matorral or Larrea stands; 700-1600 m; Ariz., N.Mex.; Mexico (Sonora).

Some plants approach Isocoma acradenia var. acradenia in leaf and phyllary morphology in southern Arizona, where the ranges of the two taxa overlap.

Common Name: burroweed

Duration: Perennial

Nativity: Native

Lifeform: Subshrub

General: Shrub to sub-shrub, 0.3-1 m tall and 1 m wide; bark of larger branches gray.

Leaves: Alternate, dark-green to gray, glandular, pinnately cleft into four to eight linear acute lobes. Main axis of leaves 2-3.5 cm long, about 1 mm broad, divisions 0.2-2 cm long, about 1 mm broad.

Flowers: Yellow, discoid, with no ray flowers, arranged into dense terminal clusters. Flowers dry and turn a light brown but remain on stems. Bracts are glandular as well.

Fruits: Cypselae, with the ribs not forming hornlike extensions.

Ecology: Found on dry slopes, mesas, and alluvial plains from 2,000-5,500 ft (610-1676 m); flowers from August-October.

Notes: Significant invader of depleted rangelands, often coming to constitute the principle cover. Susceptible to drought and is not fire tolerant. This plant is toxic to livestock.

Ethnobotany: No known uses.

Etymology: Isocoma is from the greek meaning -an equal hair-tuft- referring to flowers, while tenuisecta means thinly or narrowly cut.

Synonyms: Happlopappus tenuisectus

Editor: SBuckley, 2010