Field Hawkweed (Hieracium caespitosum) is a creeping perennial, with shallow, fibrous roots and long rhizomes.

The leaves, hairy on both sides (unlike Hieracium floribundum, which looks similar but has hair only on the underside), are up to 6 inches (15 centimeters) long, spathulate, and almost exclusively basal with the exception of 1 or 2 very small cauline leaves. The leaves lay flat to the ground, overlap, and will smother non-vigorous turf.

The stems are bristly and usually leafless, although occasionally a small leaf appears near the midpoint. Stems, leaves, and bracts have dense, blackish hairs and exude milky juice when broken.

The 1/2 inch (1 centimeter) flower heads appear in tight clusters at the top[9] of the 1 to 3 foot (1/3 to 1 meter) stems with 5 to 40 flowers per cluster. Corollas are all ligulate and bright yellow. Each single flower head is an inflorescence and each petal forms its own seed, making them each a separate flower or floret.

The seeds are shiny, black, and plumed. After maturing they are dispersed by wind, clothing, hair, feathers, and some vehicles that disturb fields or soils. H. caespitosum persists and regrows each year from rhizomes and often spreads by stolons, which can be extensive, creating a dense mat of hawkweed plants (a colony) that practically eliminates other vegetation.

Field Hawkweed prefers silt loam, well-drained soil: coarse textures, moderately low in organic matter, and moist. Its presence can be an indicator of low soil fertility or slightly acidic soils.