Yellowspine Thistle

Yellowspine Thistle

Cirsium ochrocentrum A. Gray

Asteraceae (Sunflower Family)

▲ ▼ young rosettes

▲ ▼ slightly older rosettes

▲ ▼ plants initiating flowering stems

▲ plant stems

▲ ▼ mature, flowering plants

▲ mature, flowering plants

▲ ▼ closer view of inflorescences/flowers

▲ ▼ post-flowering plants producing seed

▲ mature involucres beginning to shed seed; also showing strong yellow spines on bracts

Cirsium ochrocentrum Gray, Yellowspine Thistle: (Bayer Code: CIROH; US Code CIOC2)

Native perennial thistle that grows 1-3 feet tall, with little branching of stems
Both stems and leaves may be gray-green, grayish or whitish due to presence of many soft, white hairs
Leaf margins lobed, with lobes pointed and tipped with 0.25 to 0.75 inch long, yellow spine; leaf lobes often pointed upward; leaf bases often extend down stem slightly, producing leafy-wing appendages on parts of stem
Flower heads produced singly at top of extended leafless, white-wooly stems; bracts on inflorescence heads are tipped with strong, yellow, outward-pointing spine up to 0.5 inch long; flowers May to September
Found in full sun, disturbed sites, dry soils, prairies, right-of-ways
Very similar to native wavyleaf thistle (Cirsium undulatum), but base of leaves on yellowspine thistle extend down stem briefly, while wavyleaf thistle leaf bases do not extend down stem; also wavyleaf thistle is a creeping perennial plant with creeping roots

This is one of the native thistles that is sometimes mistaken for an invasive thistle species. Native thistles provide food and nectar for native insects (including bees and butterflies), birds and other animals, and generally should not be killed indiscriminately. Maintaining proper grazing levels can often reduce their unwanted increase in pastures and rangeland.

(Updated January 24, 2019)

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