Pilosella tristis

Pilosella tristis (synonym Hieracium triste[1]) is a North American species known by the common name woolly hawkweed. It is widespread across western Canada and the western United States from Alaska, Yukon, and Northwest Territories south as far as California and New Mexico.[2]

Pilosella tristis
In Olympic National Park
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Tribe: Cichorieae
Genus: Pilosella
Species:
P. tristis
Binomial name
Pilosella tristis
F.W.Schultz & Sch.Bip.[1]
Synonyms[1]
  • Chlorocrepis tristis (Spreng.) Á.Löve & D.Löve
  • Hieracium gracile Hook.
  • Hieracium hookeri Steud.
  • Hieracium triste Willd. ex Spreng.
  • Hieracium vestitum Fisch. ex Herder
  • Stenotheca tristis (Willd. ex Spreng.) Schljakov

Description

Pilosella tristis is a perennial herb. It produces a milky latex that often is described erroneously as sap. It is 3–35 cm (1.2–13.8 in) tall and is unbranched. The stem has long hairs and some hairs that look like stars. The entire plant rarely grows more than 30 cm (12 in; 1 ft) tall.[3][4][5]

Leaves

Pilosella tristis has basal leaves that are often in a rosette. The leaves look similar to a spoon and are 1–8 cm (0.39–3.15 in) long and 0.3–1.2 cm (0.12–0.47 in) wide. Most leaves are either hairless or have short hairs.[5]

Flowers

Each plant usually only contains one to two flowers. They are yellow and often look like dandelions. They have bracts around each flower that have grey star shaped hairs and long black gland tipped hairs. These flowers bloom from June to August.[5]

Habitat

Slender hawkweed grows in moist to wet open sites. It grows in mid-montane to alpine areas. It is most commonly seen below the timberline in areas with whitebark pine and alpine larch. It likes dry sites at lower elevations from Southern Colorado to Wyoming.[5]

References
  1. "Pilosella tristis F.W.Schultz & Sch.Bip.". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2019-01-29.
  2. Biota of North America Program 2014 state-level distribution map
  3. Rice, P., & Halpop, J. (2009). Hawkweed identification. Montana State University Extension
  4. Kershaw, L., MacKinnon, A., & Pojar, J. (1998). Plants of the rocky mountains. Auburn, WA: Lone Pine.
  5. Flora of North America, Hieracium triste Willdenow ex Sprengel, 1826.

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