Hooker Thistle

Cirsium hookerianum

Species distinguishing characteristics: 

  • Cobweb-like, woolly foliage
  • Creamy white flower heads in short-stalked clusters
  • Bracts have long, tangled, cobweb-like hairs (at least on the margins)
  • Outer rows of bracts have short spine tips
  • Deeply lobed leaves with spiny-toothed margins
  • Taproot

Family Characteristics: 

  • Multiple layers of bracts beneath the flowers
  • Flower heads composed of many smaller (often tiny) flowers, each of which produces an individual seed
  • Flowers may contain disk florets, such as those in the yellow center of a daisy, and/or petal-like ray florets
  • Undivided leaves
  • Includes the food plants lettuce, artichoke, and endive

Growth habitat: 

Erect, prickly biennial, or short-lived perennial, 40–100 cm tall, that grows from a taproot.  Grows a rosette of leaves the first year and sends up a flowering stalk the second year.

Leaves and stems: 

Cobweb-like, white-woolly foliage that thickly covers the underside of leaves.  Fleshy, hollow stems are vertically ribbed, taper toward the top, and usually unbranched.  Alternate leaves, up to 20 cm long, have a prominent whitish mid-vein and are deeply lobed with spiny-toothed margins.

Flowers: 

Few to many, creamy to dirty white (or light pink), flower heads, 4–5 cm across and 2–4 cm tall, in a dense or elongated, short-stalked cluster near the top of stems.  The uppermost flower head is usually the largest.  Each flower head is composed of many tubular disk flowers with a rounded base, over 15 mm wide, of several overlapping rows of bracts, the outer of which have short spine tips.  Bracts, up to 2 mm, are mostly the same length and have cobweb-like hairs (at least on the margins).

Roots: 

Seeds: 

Hairless, ribbed, oblong, hard-coated seeds (achenes) with a tuft (pappus) of feathery bristles.

Habitat preferences: 

Meadows, aspen groves, rocky slopes, and other open, rich, moist to dry areas at all elevations.

Interesting facts: 

The peeled roots at the end of the first summer and succulent young stalks were eaten raw, pit roasted, boiled, or ground into flour by the Blackfoot and Coastal Salish people.  The raw roots were well known to cause gas due to inulin, an indigestible starch that turns into a digestible sugar with cooking.  To eat the young leaves or stems, hold the plant upside down and peel the prickles off from bottom to top with a sharp knife.  The immature flower heads can be steamed and eaten like artichokes.  The flowers are often eaten by horses and other hoofed wild animals, and the plant responds with profuse branching.  Thistle flowers can also be chewed like gum.  The seed fluff makes good fire starting tinder.

Biological Classification: