2003: John Beaman[4] long-time curator of the Michigan State University Herbarium, and especially for his work on the floras of Mexico and northern Borneo and the taxonomy Asteraceae.

2004: David John Mabberley[5] for his work with the tropical genera Chisocheton (Meliaceae) and Grewia, on pachycaul trees and his authorship of several important books.

2010: Beryl B. Simpson[10][11] for work on the phylogeny and biogeography of several angiosperm groups (especially Krameriaceae, Polylepis (Rosaceae) and Perezia (Asteraceae)), primarily from the American Southwest, Mexico, and Central and South America.

2014: H. Peter Linder[15][16] for contributions to the systematics, biogeography, and evolution of Orchidaceae, Restionaceae, and Poaceae as well as work on identifying biogeographical patterns in the Southern Hemisphere and especially in Africa.

2019: Sandra D Knapp[22] tropical botanist and educator, advocate for conserving biodiversity, floristics, collections, the relationships between plants and people and particularly for her work with the Solanaceae.