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Questions and Answers: 2017

Question: I am confused by a posted sighting of White Snakeroot: "Sighting: Ageratina altissima at 42.2875, -71.82444 by Levin1 on October …

• Question

  I am confused by a posted sighting of White Snakeroot: "Sighting: Ageratina altissima at 42.2875, -71.82444 by Levin1 on October 16 2016" In Newcomb's wildflower guide p.436, White Snakeroot is called Eupatorium rugosum. Is this a different plant or has the name been changed? Thank You. Joan

  Answer

  Dear joanduprey, yes, the name has changed. The genus Eupatorium has been split into three different genera in new England. They are as follows: Eutrochium (whorled leaves and pink petals), Eupatorium s.s. (opposite leaves and white corollas with smooth lobes), and Ageratina (opposite leaves and white corollas with papillose lobes). Ageratina is further separated from Eupatorium by its involucral bracts of one length and pappus bristles tapering to a fine point (Euptorium has involucral bracts of 3 or more lengths and pappus bristles blunt at the apex). Ageratina altissima is the correct name for the plant referred to as Eupatoriumr rugosum in the Newcomb's wildflower guide.