Cirsium occidentale aka Cobweb Thistle

Cirsium occidentale is a perennial in the daisy family, Asteraceae. Its common names include cobwebby thistle and snowy thistle. Kew gives its native range as the western United States to northwestern Mexico. Plants For A Future lists Oregon, California, and Nevada within that range. It grows in sandy coastal sites and nearby hills. It is not native to Britain or Ireland.

This plant grows to about 3.3 feet [1 metre] tall. It can grow in cultivated beds with a sunny site. Its flowers have both male and female organs. The plant is self-fertile, so it can reproduce with its own pollen. Bees, flies, moths, butterflies, and beetles pollinate the flowers. These visitors form a broad group of insect pollinators. The supplied species accounts give no flowering months or fruit details. They also give no mature spread or detailed leaf description.

Plants For A Future describes this species as easy to grow. It accepts ordinary garden soil but needs good drainage. Sandy, loamy, and clay soils can all suit it. It tolerates mildly acid, neutral, and mildly alkaline soil. Choose full sun, since it does not grow in shade. It accepts dry or moist ground. The source lists USDA zones 8–11, yet warns of limited frost tolerance. In Britain, it recommends outdoor growing only in the mildest areas. That warning matters when choosing a permanent garden site.

Raise plants from seed or divide established plants. Sow seed where the plants will grow in spring or autumn. At 68°F [20°C], germination takes about two to eight weeks. Spring and autumn also suit division. The species is closely related to Cirsium coulteri. The two can hybridize where they meet in the wild. Plants For A Future does not flag this species as weedy. The supplied accounts give no species-specific pest or disease guidance.

The roots and stems have recorded food uses. Cook the roots; prolonged boiling is reported to improve their taste. Peel the stems before eating them raw. The roots may contain inulin, which people cannot digest. Gut fermentation of inulin can cause gas in some people. Plants For A Future reports no known hazards or medicinal uses. That hazard statement does not establish safety for pets. Its food-use rating is modest, at two out of five.