Palo Alto Thistle (Cirsium praeteriens)

The Palo Alto Thistle was described in 1918, it is known only from two collections from 1897 and 1901 respectively.

The species resembles the probably closely related Franciscan Thistle (Cirsium andrewsii (A. Gray) Petr.) but differs from that species in having long involucral spines.

The Palo Alto Thistle was not found since the beginning of the 20th century and is considered extinct.

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edited: 14.01.2019