Word of the Week: Trimorphic

Another trimorphic plant, Lythrum salicaria (purple loosestrife), is native to Eurasia and now invasive in the U.S. and Canada. Charles Darwin studied its three flower types, which he referred to as “long-styled, mid-styled, and short-styled” and conducted fertilization experiments on them in 1862 and 1863. He concluded that “Altogether there are three females and three sets of males, all as distinct from each other as if they belonged to different species.” (Darwin, 1864)


Darwin, C. R. 1864. On the sexual relations of the three forms of Lythrum salicaria. [Read 16 June] Journal of the Linnean Society of London (Botany) 8:169–171. John van Wyhe, editor. 2002-. The Complete Work of Charles Darwin Online.

Hone C. 2007. Sassafras albidum. The Virtual Nature Trail at Penn State New Kensington. The Pennsylvania State University ©2002. [Accessed 12 August 2021].

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