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(updated November 25, 2022) 

Tall Hawkweed

Hieracium piloselloides Vill.

Asteraceae (Sunflower Family)

▲ mature flowering plant

▲▼flowering stems

▲ base of plant, showing narrow leaves

Hieracium piloselloides Vill., Tall Hawkweed:  (Bayer Code:  HEIPO; US Code HIPI2)

·         European native, simple perennial weed with a taproot that produces leafless to nearly leafless stems 6-30 inches tall above a rosette of clustered leaves; stems have many stiff, outspread hairs, many with darker glands at their base, particularly in upper portion of the stems

·         Basal rosette leaves are medium to light green, alternate, with pointed or round-pointed tips; leaves usually hairless except for long white hairs along the midvein on the leaf underside, and along the smooth leaf margins; leaves have short or no petioles

·         Head inflorescences are 0.5 to 1 inch in diameter, dandelion-like, in clusters at tips of usually leafless stems (occasionally one or two leaves on stem near basal rosette); heads have no disk flowers, but 60-80 yellow ray flowers; the yellow “petals” have 4 notches in their flattened tips

·         A single row of bracts below the head form a cylindrical to barrel-shape; individual bracts are green, linear, with pointed tips; bracts have a center ridge of black, gland-based hairs; stems just below the heads have the same black hairs

·         Flowering is from mid-spring through late summer

·         After flowering the florets from the head become a globe of white hairs from the pappus (parachute-like hairs) attached to small, brown to black, mature seed/fruit

·         Prefers low-fertility, acidic, sandy soils; found in lawns, cultivated fields, pastures, prairies, non-crop areas, right-of-ways

·         More common in northern Midwest, and is a problem due to its ability to rapidly reproduce by seed

·         Similar species:

·         Similar species:

     o   Orange Hawkweed (Hieracium aurantiacum) looks very similar to yellow hawkweed in leaf shape, growth form and height, except it has orange to red-orange florets in its flower heads

     o   Yellow Hawkweed (Hieracium caespitosum) looks very similar to orange hawkweed in leaf shape, growth form and height, except it has bright yellow florets in its flower heads

     o   Common Catsear (Hypochaeris radicata) has similar yellow flowers, but has a more branched, open clustering of flower heads, and individual heads have long supporting stalks; also the basal rosette leaf margins of common catsear are widely lobed, not smooth or toothed, as with yellow hawkweed

     o   Smooth Hawksbeard (Crepis capillaris) has similar, but smaller, yellow flowers, but they are in larger, more open clusters; plus stems and basal leaves are hairless, and basal leaves have deep, pointed lobes, and there are smaller leaves along the flowering stems

     o   Dandelion (Taraxacum officinale) has similar flowers, but has nearly hairless, deeply toothed rosette leaves, and flowering stems are single, pale green to pinkish, hollow and leafless

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