Onopordum acanthium aka Cotton Thistle

Onopordum acanthium, also known as cotton thistle or Scotch (or Scottish) thistle, is a biennial flowering plant in the Asteraceae family. It is native to Europe and Western Asia, from the Iberian Peninsula to Kazakhstan, and north to central Scandinavia. It has also been widely naturalized in other parts of the world, including large populations in the United States and Australia. The plant is a vigorous grower with coarse, spiny leaves and noticeable spiny-winged stems. In the first year, the plant produces a large rosette of spiny leaves, forming a fleshy taproot that can extend down 30 cm or more for food reserves. In the second year, it can grow up to 3 meters tall and 1.5 meters wide, with deeply lobed leaves covered in white woolly hairs. The stem can be 10 cm wide at the base and has a vertical row of broad, spiny wings extending to the base of the flower head. The flowers are globe-shaped and range from dark pink to lavender, with each stem producing one or more flower heads. The plant is androgynous, with both pistils and stamens, and sits above numerous, long, stiff, spine-tipped bracts. After flowering, the plant produces approximately 8,400 to 40,000 seeds per plant. While this plant can be useful, it can also be poisonous and may need to be removed. Mechanical removal or cutting a few centimeters below the soil surface can be effective for small infestations. Mowing during early flowering can reduce seed production, but should not be done following seed set as it increases chances for seed dispersal. Chemical treatments can be effective, but all herbicide treatments should be applied at the rosette stage of the plant. Biological control agents have not been specifically released for cotton thistle control in the United States, but a thistle crown weevil and Australian painted lady butterfly have shown potential. In contrast to its hardy and invasive nature, cotton thistle is also a super rare houseplant that needs regular watering and abundant sunlight to thrive. It should be placed no more than 3 feet from a window. It is important to note that this plant should not be confused with Cirsium vulgare (spear thistle), which is also known as Scotch or Scottish thistle and is the national flower of Scotland. Spear thistle is native to Britain, while cotton thistle is non-native.