Platte Thistle
Platte Thistle
Cirsium canescens Nutt.
Asteraceae (Sunflower Family)
▲ ▼ early rosette stage
▲ ▼ plants preparing to flower
▲ ▼ mature, flowering plants
▲ ▼ closer view of inflorescences/flowers
Cirsium canescens Nutt., Platte Thistle, Prairie Thistle: (Bayer Code: CIRCN; US Code: CICA1)
- Native biennial or short-lived perennial that grows about 1-3 feet tall
- Stems and leaves usually moderately to densely covered with gray to white hairs
- Leaf outline is oval, but leaf margins moderately to deeply lobed, often with lobes curved toward tip of leaf to give a strong, wavy edge; lobes are tipped with spines
- Head inflorescences in bud are globe shaped; in flower are about 2-3 inches diameter, with white to sometimes pale lavender ray flowers with cup-shaped, bract-covered base
- Bracts below head are lanceolate, pointed with whiter band in middle and tipped with a tan to yellow spine that points outward
- Similar native thistles with whitish stems and leaves all tend to have purplish flowers (Flodman thistle, wavyleaf thistle, yellowspine thistle), while Platte thistle will have white flowers
- Non-native Scotch thistle (Onopordum acanthium) also can have whitish stems and leaves, but it will have very large leaves, purplish flowers and large, spiny, leafy wings along the stems
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.
(Posted January 23, 2019)