Hieracium piloselloides (Glaucous King-devil)

Plant Info
Also known as: Tall Hawkweed, King-devil Hawkweed
Genus:Hieracium
Family:Asteraceae (Aster)
Life cycle:perennial
Origin:Europe
Status:
  • Invasive - ERADICATE!
Habitat:part shade, sun; open fields, roadsides, disturbed soil, high grade prairie
Bloom season:June - August
Plant height:12 to 40 inches
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 7+petals Cluster type: flat Cluster type: panicle

[photo of flowers] 10 to 30 yellow dandelion-like flowers in a flat to open cluster at the tip of a long mostly naked stem. Individual flowers are about ¾ inch across, often with dark glandular hairs on the bracts and flower stalks. The compact clusters become more open as the flowers mature.

Leaves and stems: Leaf attachment: alternate Leaf attachment: basal Leaf type: simple

[photo of leaves] Leaves are mostly basal in an erect rosette around the stem, 3 to 7 inches long, ¼ to ¾ inch wide, lance-elliptic tapered to a rounded point, smooth or sparsely toothed around the edges. Sometimes 1 or 2 reduced leaves are also on the lower part of the flowering stem. Leaf surfaces have a waxy bloom, the upper surface smooth or with scattered stiff hairs, the lower surface with stiff hairs along the midrib. Stems are waxy smooth at the base becoming sparsely hairy to glandular hairy near the flower cluster. Stolons (runners) are usually absent.

Notes:

A relative new-comer in many parts of the state, Glaucous King-devil and other non-native weedy hawkweed species have expanded rapidly west and south the past twenty years from the Duluth area. It is not uncommon to see entire abandoned hay meadows and road ditches completely overrun. This species can be difficult to distinguish from Meadow Hawkweed (Hieracium caespitosum) which  often grows side-by-side with it. Typically Glaucous King-devil is less hairy on all parts of the plant, its flower cluster less compact, and typically has no stolons. To complicate matters there is a third similar non-native hawkweed, Hieracium x floribundum, which is a hybrid between H. caespitosum and another European hawkeed, H. lactucella. It's not as widely reported but likely more prevalent than documented. Its above ground portions are very similar to H. piloselloides but the tap root is long and slender, and it also produces stolons and grows in mats. It might also be easy for the untrained eye to confuse all the hawkweeds with sow-thistles, but sow-thistles all have shiny leaves that are lobed and have spiny teeth along the leaf edges.

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More photos

Photos courtesy Peter M. Dziuk taken in Aitkin and Pine counties.

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